Send Orders for Reprints to [email protected] Recent Patents on Engineering, 2014, 8, 41-49 41 Patents on the Advances in Dairy Industry

Amalia Conte, Valentina Lacivita, Daniela Esposto, Maria A. Saccotelli and Matteo A. Del Nobile*

Università di Foggia, Dipartimento di Scienze Agrarie, degli Alimenti e dell’Ambiente, Via Napoli, 25 – 71122 Foggia, Italia

Received: November 29, 2013 Revised: January 27, 2014 Accepted: February 11, 2014

Abstract: The current work is aimed to give an overview on the most relevant patents available on dairy industry. To the aim, both processing and product innovations will be reviewed. In particular, novel tools applied to traditional dairy plants to optimize the heat treatments and reduce the disadvantages derived from the direct use of heat on product quality will be reported. Advances applied for delivering dairy starter cultures to better control contamination of process lines will be also discussed. Some relevant inventions to reduce the length of time required during the manufacturing or to decrease the aging time of dairy products will be presented. Finally, the advances to enhance functional and/or sensory properties of dairy products will be reported. In particular, processing methods to achieve milk-derived products with desired morpho- logical and/or compositional characteristics will be reviewed. Keywords: Dairy industry, dairy quality, functional products, starter culture, thermal treatment.

INTRODUCTION types of beverages, but the applied heat may also cause un- desirable biochemical and nutritious changes that may affect The dairy sector is multifunctional in nature, and contrib- sensory attributes of the final product. A well-known prob- utes to sustainable agricultural development and food secu- lem of heat-treated milk is the fouling of the heating sur- rity. The global trade is dominated by developed countries, faces, i.e. milk solids are deposited on the surfaces decreas- contributing to 62% of the imports and 92% of the exports ing the heat transfer rate. Moreover, thermally treating milk [1]. Milk processing has a long tradition, as demonstrated by often results in color changes and/or gelation during process- the large variety of typical cheeses produced in different ing or extended storage. Therefore, various inventions were areas all over the world. High-income consumers highly ap- aimed to enhance the efficacy of thermal treatments and preciate productions strictly connected to their origin area minimize the deleterious effects on milk-derived products. and which are able to evoke the history, and the culture of The risk of contaminating the process line with undesired their production areas. Sometimes, inhibitory elements to microorganisms always promoted researches and inventions high competition level can occur, mainly ascribed to a break- in dairy sector. To this aim, improved methods of delivering ing up of the product supplies with a consequent inability of dairy starter cultures to the process line were invented with the operators to realize a consistent income level, the limited the advantage to inoculate the milk in a closed dairy process possibility to develop projects able to characterize dairy line without opening the system to the environment. products and the difficulty to realize high production. How- ever, consumer demand and current market conditions war- The dairy industry, and more particularly the cheese in- rant investigation on dairy processing technologies that can dustry, for many years has attempted to reduce the length of deliver improved product quality and stability and reduced time required during the manufacturing process to obtain the energy use during processing, without compromising prod- desired and expected performance of a cheese. As a fact, uct and process safety. there are various inventions to reduce the length of time re- quired during the manufacturing dairy process. A major technical problem that has nagged the dairy in- dustry from its inception is the development of techniques Several efforts in dairy sector were also made to improve for fully sterilizing milk without perceptibly changing its on one hand the physical properties of milk-derived food taste. Milk used for production of dairy products is very of- including viscosity, rheological properties, particle size and ten heat treated by pasteurization. Thermal pasteurization is product stability, and on the other to produce dairy food with quite efficient in preventing microbial spoilage of many low levels of lipids. Hence, in this work an overview dealing with the most *Address correspondence to this author at the Università di Foggia, Dipar- relevant patents available on dairy industry is presented. In timento di Scienze Agrarie, degli Alimenti e dell’Ambiente, Via Napoli, 25 particular, patented apparatus to optimize the thermal treat- – 71122 Foggia, Italia; Tel: +39 0881 589242; ment of milk to produce dairy products are presented. In E-mail: [email protected] addition, some details were also provided on a new method

2212-4047/14 $100.00+.00 © 2014 Bentham Science Publishers 42 Recent Patents on Engineering, 2014, Vol. 8, No. 1 Conte et al. of delivering dairy starter cultures to better control contami- heated curd, such as cheese known "Grana Padano" or the nation of dairy process lines. Novel devises for reducing one known "Parmigiano-Reggiano", where the milk is co- production time or aging period of dairy products are also agulated by means of heat-exchange coagulation devices. widely discussed. Finally, the most recent techniques to en- The conventional conical coagulation vessels have a capacity hance functional and/or sensory properties of dairy products of approximately 1200 liters with a heat-exchange surface of are reported. approximately 4.5 square meters. This is, in practice, the maximum size for an exchanger of this type, since any fur- TEST-PATENTS ther increase would cause an excessive increase in the vol- ume of the liquid to be treated, with respect to the heat ex- Advances in Thermal Treatments of Milk to Produce change surface and would slow down the heating of the Dairy Products milk, making it impossible to comply with the "cooking time" required for the typical production of these cheeses. The science of preserving food products has been studied This fact is a very severe limitation to production and sig- continuously from the stone age to the present day. Liquid nificantly affects costs of some kinds of cheese. Therefore, dairy products, such as milk, may be thermally processed to the main aim of the EP 0620977 [3] patent is to solve the increase their stability. Unfortunately, thermally treating of problems described above by providing an apparatus for the milk often results in color changes and/or gelation during heat treatment of liquid food products, particularly for heat- processing or extended storage. For example, lactose in milk ing milk in the making of dairy products, which allows to heated to high temperatures tends to interact with proteins treat, within the required time, considerably larger masses of and results in an unsightly brown color. This undesired con- liquid food product than those that can be treated with cur- dition is often referred to as browning, since browning reac- rently commercially available processes and equipment. It tion gels may form, under certain conditions, a three- consists in immersing a heat exchanger in the liquid to be dimensional protein matrix. Many efforts in heat treatment treated, which is contained in a vessel, and in moving said of fluid products were made in the 19th century with the liquid over the heat-exchange surface of said heat exchanger. development of pasteurization, a process of partial steriliza- In this manner, since the heat exchange surface is fully inde- tion involving subjecting a substance, particularly a liquid, to pendent of the dimensions of the vessel containing the liquid a temperature for a period of time that destroys disease- to be treated, it is possible to perform heat treatments, (heat- causing microorganisms but alters the main characteristics. ing or cooling processes) at rates and temperature required To solve this problem the patent US 4591463A [2] provides by a given production. Thus, it is possible to cook large an improved process and apparatus for sterilizing food prod- masses of curd in its whey within the "cooking time" and at ucts without adversely affecting their taste or other physical the temperatures required to produce Grana Padano or Par- properties. The invention has particular application to fluent migiano Reggiano, without limitations due to the amount of food products. Another object is the provision of a novel milk to be treated. Therefore, one object of the invention is method and apparatus for heating fluids, such as milk, to a to provide a process that is highly versatile in use so as to selected temperature for a set interval of time with a mini- allow to vary, according to the requirements, both the mum of turbulence or agitation. This novel method causes amount of liquid to be treated and the treatment time, as well low denaturation of whey proteins, comparable to that of as the temperature to perform a particular process. Another pasteurization process. A still further object of the present object of the same invention is to provide an apparatus which invention is the provision of a novel apparatus for sterilizing is simple to clean and highly reliable in operation, so as to fluid foods wherein an isolated film of the product is formed offer the greatest assurances of hygiene and avoiding con- and is subjected to heat treatment at a particular temperature taminations of the liquid to be treated. It should be noted that for a selected time interval, during which it is subjected to an the apparatus for performing the process according to the absolute minimum physical stress. Briefly, these and other invention may also have multiple heat exchangers to be im- objects of the invention are attained by the provision of a mersed in the same treatment vat, according to the amount of unique apparatus in which the fluid to be treated is first liquid to be treated. Although the process and the apparatus formed into a continuous isolated film which is kept free have been conceived particularly to perform the heating from contact with any further hotter than itself for a selected process for milk coagulating in the making of heated-curd interval of time. In this patent it is revealed that a proper cheese, it may nonetheless be used advantageously to heat time-temperature relationship is the key to removing the un- milk in the making of other kinds of cheese too, as well as desirable effects of thermal perturbation. In particular, if the for any heat treatment required in dairy industry. The process milk is heated to a maximum temperature, appropriate heat according to the invention may furthermore be used to heat treatment for sterilization is attained without thermal taste or cool in a preset time not just milk, but other liquid food distortion. In view of the sensitivity of milk to physical stress products such as musts during fermentation of wine, or in during heating, a significant aspect of the present invention other fields. Indeed, this apparatus is susceptible to numer- is the provision of an apparatus for physically handling the ous modifications and variations. milk during the process of heating. The concentration of milk is often desired because it al- In the dairy industry, the conversion of milk into other lows for smaller quantities to be stored and transported, products generally entails heat treatment with operations that thereby resulting in decreased storage and shipping costs. usually occur in very short times. A typical example of this However, the production of highly concentrated milk can be requirement is the process for producing cheese made from difficult, because the concentration of milk generates even Patents in Dairy Sector Recent Patents on Engineering, 2014, Vol. 8, No. 1 43 more pronounced problems with gelation and browning. For comprising monoglycerides, lecithins, diglycerides, diacetyl instance, milk that has been concentrated at least three fold tartaric acid esters of mono-and diglycerides, sucrose esters has an even greater tendency to undergo protein gelation and of fatty acids, sodium steoroyl lactylate, citric acid esters of browning during its thermal processing. Additionally, such mono-and diglycerides, or a combination thereof. Preferred concentrated milk also has a greater tendency to separate and emulsifiers are monoglycerides, lecithins, diglycerides and form gels over time as the product ages, thereby limiting the combinations thereof. Examples of such emulsifiers are Hy- usable shelf life of the product. So, the objective of the US mono™ 8903 and Dimodan™ hp. The amount of emulsifier 8236362 B2 [4] patent is directed to a shelf stable and sen- is dependent on the type of emulsifier selected and the rela- sory-pleasing concentrated dairy liquid having greater than tive amount of protein present, but generally it is from 0.05 about 8.5% total protein. The stable concentrated dairy liquid to 1 wt%. It will be appreciated that for each emulsifier there has reduced level of soluble protein prior to concentration is an optimal amount for its functioning. using ultra-filtration; a stabilizer and a mouth-feel enhancer are added to the intermediate dairy liquid prior to steriliza- STARTER CULTURES IN DAIRY INDUSTRY tion; the intermediate dairy liquid is resistant to gelation and browning during sterilization, and it remains acceptable for Microorganisms are involved in the manufacture of most at least six months of storage under ambient conditions. In dairy products. Bacterial cultures, in particular lactic acid general, the stable dairy liquid is formed through a multi-step bacteria, are essential in the making of all fermented cheese. thermal process to achieve desired sterilization value and Cultures of such harmless bacteria are called dairy starters product characteristics. In particular, the method comprises and they impart specific features to the various dairy prod- fore-warming, concentration by ultra-filtration and steriliza- ucts by performing a number of functions as aid the coagula- tion steps that provide the overall thermal treatment. The tion of milk during the cheese making. A further example is method to produce such stable concentrated liquid utilizes that the rapid lactic acid development throughout the produc- specific thermal treatments to produce a stable concentrated tion process caused by the starter cultures restricts growth of dairy liquid that can be stored under ambient conditions for contaminating microorganisms. In cheese making, starter more than 6 months. The method balances such thermal cultures promote the exudation of whey from the curd. The treatments to achieve the desired sterilization and, at the lactic acid-producing bacteria also produce proteolytic en- same time, to achieve sufficient cross-linking of serum pro- zymes, that promote the degradation of cheese proteins and tein in the concentrated milk to resist gelation and minimize contribute to the ripening of cheese. Additionally, lactic acid browning reactions. bacterial cultures ferment lactose and citric acid to aromatic compounds, such as diacetyl and acetaldehyde that confer The sterilization by Ultra High Temperature (UHT) the desired aroma and taste to fermented milk products. treatment of milk and other protein containing suspensions Presently, commercial starter cultures are distributed as fro- raises temperatures ranged from 135 °C to 150 °C for only a zen concentrates in a medium of milk components, nutrients few seconds and creates a product which is stable at room and growth stimulating compounds. Under these conditions, temperature for several months. This preservation technique the viability of the cultures is preserved for extended periods is especially used for drinks such as milk. Although dairy of time, and after thawing the cultures can be inoculated di- products may be microbiologically stable for a long time, rectly into milk without intermediate transfer. Another pres- there may be some defects that could limit the shelf life of entation of commercial starter cultures is as freeze-dried or these products. One of these defects that have been discussed lyophilized cultures in the form of powder. In this form, the extensively in the art is UHT gelation, also referred to as age starter can be shipped without refrigeration, but storage be- thickening. This defect is specifically observed for UHT low freezing temperature is recommended. There are several treated products or otherwise sterilized products that are examples of mechanical devices for the transfer of a starter heat-treated and is not observed for products that have not culture into the process line. The European patent EP undergone such high temperature in heat treatments. For 1009243B1 [6] reports in the state of art various other patent example, products that are only pasteurized do not show this documents that are briefly summarized. One invention de- defect. Gelation is generally linked to the formation of a scribes an example of a continuous fermentation process for space-spanning network and therein differs from other phe- manufacturing yoghurt where a starter culture is initially fed nomena, such as sedimentation, which is more about a spa- to the fermentation vessel from an inoculum vessel; another tial redistribution of ingredients and describes the phenome- invention discloses a device for aseptically transferring a non of increase of viscosity and/or elasticity of the product. liquid starter culture contained in a hermetically closed It has been found that the addition of a small amount of box/can to a fermentation vessel another patent discloses a emulsifier reduces the gelation of sterilized protein contain- mechanical device adapted to open a conventional container ing suspensions. Therefore, the invention of the EP 1946644 for starter culture under aseptic conditions with subsequent A2 [5] patent relates to a sterilized aqueous suspension com- transfer of the starter culture from the opened container into prising protein and fat or a fat replacer and from 0.01 wt% to the process line; another invention reports a cartridge or bag 1 wt% emulsifier with a hydrophylic/lypophylic balance containing a biological medium used in tissue cell cultures; equal or below 16. In a further aspect the invention relates to another invention describes a method for aseptically transfer- use of an emulsifier to reduce the age gelation in sterilized ring bacteria in powdered form from a closed container into protein containing suspensions, especially UHT treated a rehydration vessel by means of a gas stream. The currently milks. The emulsifier is preferably selected from the group used methods of applying dairy starters involve several prob- 44 Recent Patents on Engineering, 2014, Vol. 8, No. 1 Conte et al. lems in modern dairy plants where process lines are essen- lower part with a pair of shearing blades, namely an upper tially completely closed systems. Any process step which blade and lower blade, that act on the column of curd and involves closed system to be opened to the environment evi- shear it into loaves of a desired height. The lower open end dently involves a serious risk of contaminating the process of the forming column cooperates with a conveyor, on which line with undesired microorganisms such as milk spoilage are transported the moulds or matrices in which the sheared bacteria. It is therefore an important objective of the inven- loaves of curd are held for movement to the successive proc- tion described in the patent EP 1009243B1 [6], to provide an esses, such as pressing and marking. Moreover, the cheese- improved method of delivering dairy starter cultures to the making reactor cooperates with possible salt-dispensing process line. The method is adapted to the increasing de- means. mand for stricter control of contamination of closed dairy When producing semi-hard or hard cheeses, another process lines. It is an essential feature of this method that the problem that may increase the time process is the phase of starter culture used for inoculation of milk can be supplied to aging. Traditionally, cheese requires an aging for approxi- the dairy plant as a concentrated culture such as frozen, dried mately 7 to 21 days, to develop characteristic taste and tex- or liquid culture contained in a sealed enclosing packaging ture, as well as acceptable baking characteristics. All of the which is provided with outlet means for connecting the major components of cheese, carbohydrates, protein, and fat, packaging directly to the process line. The sealed enclosing are subject to change during aging. Through a complex vari- packaging is made of a flexible material. Evidently, this fa- ety of metabolic processes, enzymatic lipolysis and proteoly- cilitates distribution and reduces significantly the require- sis, these principal components are metabolized to lactic ment for storage space. As mentioned above, the sealed en- acid, peptides, amino acids, and fatty acids. Cheese aging closing packaging containing the starter culture is provided requires considerable time, space, and energy that increase with inlet and outlet means for connecting the packaging to the cost of the finished product. For this reason many ap- the process line. The inlet means serves the purpose of per- proaches reported in the scientific literature have been tried mitting the introduction of an aqueous medium into the to find ways to accelerate the ripening process for several packaging containing the starter culture, without the risk of types of cheese [8-12]. However, with regard to all of these contamination, to obtain a stable aqueous suspension of the experimental researches, some aging times have been indi- culture in the packaging. When a stable suspension has been cated as being necessary, whereas, the European patent EP obtained, it is introduced into the dairy process line that con- 0535268 A1 [13] provides a process which eliminates the tains milk and it is performed by connecting, under essen- requirement of aging, or any further treatment of mozzarella tially aseptic conditions, the outlet means of the enclosure to cheese, yet achieving similar melt characteristics to those of one or more process line units, whereby the starter culture prior art cheese that has been aged. The present invention suspension is combined with the milk. The introduction of also relates to the composition of mozzarella cheese pro- the starter culture suspension into the process line may occur duced using this process. The milk-fat, protein and moisture due to gravity or by means of a pumping tool. components are adjusted in a manner to achieve the desired NOVEL DEVISE FOR REDUCING PRODUCTION performance. In fact, composition to which mozzarella TIME OR AGING PERIOD OF DAIRY PRODUCTS cheese is held in the present process is a moisture content of at least 52% and a wet milk-fat content of at least 18%. One The European patent EP 0691074A1 [7] describes the of the purposes of aging is to allow the diffusion of salt from invention so as to overcome all these drawbacks and to im- the outer crust to the center of mozzarella. Since aging is prove the process of syneresis and/or drainage of the curd by omitted, it is preferred to mix into the fresh cheese curd standardizing it from a quality point of view with a continu- 0.8% salt. The mozzarella cheese produced by the present ous process which enables environmental contamination and process, after being cooled in the brine, can be held for up to contact between the work force and the product to be re- 48 hours prior to being comminuted and packaged. It was duced to a minimum, and also so as to obtain a versatile de- discovered that the relationship between the moisture content vice which can be adapted to a plurality of types of cheeses and the state of the protein is such that within the first 48 and to various processing methods. To be more exact, the hours after completion of the brining, the desired melt char- invention concerns a method for the automated production of acteristics can be achieved, but that after this time there is a cheese in a plant comprising at least one cheese-making re- shift in this relationship, such that only by aging the cheese actor. The reactor consists of a steel plate cylinder positioned for a week or more the desired melt performance can be ob- horizontally, inclined or vertically in relation to the ground, tained. One can generally arrest and preserve the desired at the two ends of which there are a feeder inlet and a dis- properties in the un-aged cheese by freezing it within a 48 charge outlet for the curd. The reactor is positioned within a hour period. Therefore, this method allows to obtain the tank for the recovery of liquids; the tank is associated with a proper characteristics required to mozzarella cheese variety, perforated jacket suitable for the expulsion and progressive although eliminating the aging process. drainage of the liquid whey contained in the curd, that is to NOVEL TECHNIQUES TO ENHANCE FUNCTIONAL say, suitable for the syneresis during the movement of the AND/OR SENSORY PROPERTIES OF DAIRY PROD- curd within the reactor. The reactor discharges continuously UCTS from its outlet, when syneresis is completed, the curd into the forming column. The forming column suitable for the Commercial food manufacturers strive to consistently compacting and accumulation of the curd, cooperates in its deliver high quality, nutritious food products that can be Patents in Dairy Sector Recent Patents on Engineering, 2014, Vol. 8, No. 1 45 manufactured in an efficient manner, and that have an ac- regular or standard emulsification methods. The increased ceptable shelf life in the retail market. Today food industry sphericity is believed to provide a greater surface area to the has the benefits of many years of research on various food dispersed phase. The smaller particle equivalent spherical ingredients and food processing techniques that enable the diameter distribution results in greater uniformity among the commercial food manufacturer to achieve these goals. How- dispersed particles. These factors combined enable the added ever, as consumer demands change and increase, the food stabilizers to function more effectively. As a result, a smaller manufacturer is faced with new challenges in food technol- amount of emulsifiers or stabilizers needs to be added to a ogy, and particularly in food processing techniques. Many food product to achieve the same functionality as in a food commercial food products on the market involve some sort product prepared using a conventional homogenizer and of emulsion, suspension, or other technology in which a het- conventional levels of emulsifiers or stabilizers. The method erogeneous combination of ingredients is used to provide the of present invention can be used to construct a fat globule in necessary and desirable functional product attributes. As a way that results in functional and sensory properties simi- used herein, the term “functional attributes” or “functional lar to that obtained by using, for example, twice the level of properties” shall be defined as the physical properties of the emulsifiers or stabilizers to make a conventional ice cream. product, including, but not limited to, the product viscosity, This effect can be applied to all dairy products in which the rheological properties of the product, particle size and prod- fat is used as a tool to manipulate functional and sensory uct stability. These functional properties affect the sensory properties of the product. It has been unexpectedly discov- properties of the product, including, but not limited to, the ered that even products having a very low level of fat can flavor, aroma, mouth-feel and texture of the product as per- benefit from the modification of particle morphology in ac- ceived by a consumer. Although the use of emulsifiers and cordance with the present invention. The ultrasonic energy stabilizers has greatly benefited food manufacturers, there is can be applied to the product at any stage during processing a growing consumer preference for reducing or eliminating at which the product is in a flowable state. In one embodi- emulsifiers and stabilizers in food products, while maintain- ment, the product is preferably treated with ultrasound en- ing or improving the functional properties of the food prod- ergy before or after a heating/pasteurization step. The present uct. This poses a new challenge for commercial food manu- invention can be used for any type of product, including, but facturer. The American patent US 7947321 B2 [14] is di- not limited to, the following milk products (fresh, organic, rected to a method for improving the functional properties of and pasteurized): skim milk, 1% milk, 2% milk, whole milk, a product containing particles. The method involves process- flavored milk (such as chocolate, vanilla, strawberry, and the ing the particles to modify a morphological property of the like), low carbohydrate dairy beverages, cream, soft serve ice particles. Examples of morphological properties that may be cream, ice cream, ice milk, ice cream mix, shake mix, Italian modified through this method include sphericity, equivalent ice, sorbet, sour cream, buttermilk and yogurt. spherical diameter, shape, aspect ratio, and combinations Some inventions tried to reduce the content of saturated thereof. The present invention is also directed to the unex- fat in dairy products. For instance, the United States patent pected discovery that numerous parameters of particle mor- US 5395631 [17] describes a method for preparing a cheese phology can be manipulated to obtain desirable functional product having a low level of saturated fat and cholesterol, a properties. It has been observed that for a given type of par- high level of polyunsaturated fat and good sensory proper- ticle, for each parameter of that particle's morphology, there ties. It is prepared by adding a fat-based cream obtained by is a preferred range of values, and if the distribution of parti- homogenizing a fat phase and a water phase, the fat being cles within that preferred range is fairly uniform rather than coated by a membrane such that in a casein lattice the fat random, a product having superior functional and sensory substantially mimics milk fat. The cream product is added to properties will result. a cheese vat either alone or in combination with a milk fat The patent US 6861080 [15] describes a process for mak- and processing using conventional techniques to form ing a cream cheese product that does not contain conven- cheese. The cream is prepared by adding a blend of vegeta- tional emulsifiers. This patent describes a process in which ble pasteurized oils such as soya oil and/or coconut oil, hy- the average particle size of the fat component is reduced as drogenated soya oil and/or hydrogenated coconut oil, an compared to a conventional product in order to achieve de- emulsifier to an aqueous phase comprising a pasteurized sired firmness and textural qualities. Other methods for blend of water and a stabilizer such as gelatin. The fat-in- processing emulsions or other similar combinations with water emulsion thus formed is then blended and homoge- little or no emulsifying agents include treating materials with nized to form the cream. Preferably, the water is heated to ultrasound energy. The US Patent 0008739 [16] also de- approximately 80°C pasteurization prior to addition of the scribes treating a low-viscosity fluid with ultrasound energy vegetable fat and fat and water phases are mixed with a to inactivate microorganisms in the liquid and to reduce the blender to uniformly distribute the fat phase in the aqueous size of fat globules in the liquid. As a result, a smaller quan- phase prior to homogenization. This step is preferably car- tity of fat or fat-containing ingredients needs to be added to a ried out in one or more stages, each stage being at a pressure food product to achieve the sensory properties of a full-fat from 100 to 4.000 psi, and at a temperature in the range of product made using conventional homogenization tech- approximately 40 °C to 70 °C. The milk fat source may niques. While not intending to be bound by theory, it is be- comprise pasteurized skimmed, semi-skimmed or low-fat lieved that ultrasonic energy can be used to treat a fat- milk. Finally, in this invention the cheese contains in part containing starting material to generate a dispersed phase milk fat, the ratio of milk fat to vegetable fat being in the having fat particles with greater sphericity and smaller than range 0:1 to 3:1. 46 Recent Patents on Engineering, 2014, Vol. 8, No. 1 Conte et al.

It is well known that dairy products and process streams is contacted with the solvent in a contacting device suitable are a complex mixture of proteins, lipids, sugars and miner- for continuous processing, such as, but not limited to, a noz- als. At present, there are limited methods available for ex- zle, static mixer or porous membrane contactor. Separation tracting and refining specific components from such streams, of the defatted dairy stream or dairy product and near-critical and the separation of lipids from proteins in whey-based solvent thus may take place immediately after the contacting streams is difficult. However, these methods are often not device, and the contacting time is thus of the order of sec- cost efficient and often do not produce the desired yields. onds. The treatment of dairy products with moisture contents Also, certain extraction processes must be done under condi- greater than 75% in a continuous manner with short contact tions that irreversibly alter the physical properties of the times enables the extraction of lipids leaving an aqueous separated components (i.e. the denaturation of proteins). It is stream containing substantially defatted, soluble dairy pro- therefore an object of the present American patent US teins. The desired temperature range, especially for dairy 7919131 B2 [18] to provide an alternative or improved proc- streams containing whey proteins, is about 40 to 60 °C. Over ess for extracting lipids from a range of dairy products and this narrow range, it is known that whey proteins reversibly dairy process streams. The present invention relates to proc- unfold in solution, and it is postulated that this unfolding ess for treatment of dairy products to produce lipids and sub- enables the near critical solvent access to the lipids to enable stantially defatted protein streams. More specifically, it re- extraction. Operation outside the preferred region is possible lates to the use of near critical fluid extraction techniques to but leads to lower yields and freezing of products for tem- extract lipids from liquid dairy products and dairy process peratures below the desired range, and to thermal denatura- streams. In a first aspect, the invention broadly comprises a tion of proteins for temperatures above the desired range. method for treating a dairy product or a process stream com- The lipid extracts can be used in health foods, dietary sup- prising at least these steps: i) contacting said dairy product or plements, pharmaceuticals and cosmetics, while the depleted dairy process stream with an ether-based solvent that is par- dairy product or dairy process stream (substantially defatted tially miscible with water, said ether-based solvent being at a protein streams) may be used in dairy products (e.g. cheeses, near critical temperature and pressure, to produce a near cultured foods and beverages, ice-cream, chocolate), nutri- critical fluid phase containing lipids; ii) separating the near tion bars and baked goods. critical fluid phase from the dairy product or dairy process When milk is processed into dairy products there are a stream to produce a substantially defatted dairy product or number of properties of the milk that are desirous, depending dairy process stream, wherein the dairy product or dairy on the product to be produced, e.g. low tendency to produce process stream has a moisture content of greater than 75%; fouling of equipment, good emulsification properties and iii) reducing the pressure of the near critical fluid phase to high heat stability. Specifically, for production of butter, a recover the lipids. Useful lipids present in dairy products and high yield of butter from the cream is desirous, and when dairy process streams include phospholipids and sphingolip- producing liquid acidified milk drinks, a low viscosity may ids. Most preferred, dairy product or process streams useful be desired. The present American patent US 8226995B2 [23] according to the present invention may be selected from relates to a method for producing fractions of a milk compo- whey, whey protein concentrate retentates, whey protein sition by treating a milk with a phospholipase and separating isolate by-products, butter by-products, anhydrous milk-fat it into at least two fractions with different fat content. The by-products or lipid containing dairy effluents. In this inven- fractions obtained have improved properties for producing tion, the solvent used is dimethyl ether or a mixture of di- food products, e.g. fractions with reduced surface tension, methyl ether and water at or below the solubility of water in fractions that lead to increased yield of butter upon churning, dimethyl ether. Preferably, the solvent is gaseous at room and/or fractions that lead to improved properties of milk temperature and is at a pressure of at least the vapor pressure powder products produced there from. The invention further at the extraction temperature. The dimethyl ether has previ- relates to a method for producing food products from one or ously been used in the extraction of flavors and aromas from more of the fractions obtained. In further aspects the inven- solid food materials [19, 20], lipids from raw egg yolk [21] tion relates to methods for producing condensed milk, milk and dried egg powder [22]. Contrary to these last inventions, powder, butter and dairy spread from a milk composition in the patent US 7919131B2 [18] has been found that the treated with a phospholipase. Consequently, the invention denaturation of protein obtained by dimethyl ether extraction relates to a method for producing fractions of a milk compo- techniques can be reduced or eliminated by ensuring that the sition, comprising: i) treating a milk composition with a moisture content of the starting dairy product or dairy stream phospholipase; ii) separating the treated milk composition is greater than 75% and that addition of water to the di- into at least two fractions with different fat content. The en- methyl ether as a co-solvent, to account for water that is co- zymatic treatment in the process of the invention may be extracted with lipids, assists in the prevention of denatura- conducted by dispersing the phospholipase into the milk tion. In addition it has also been found that the short contact composition and allowing the enzyme reaction to take place times that result from the continuous process of the invention at an appropriate holding-time at an appropriate temperature. (between the solvent and the dairy product or dairy stream) In a further embodiment, the invention relates to fractions minimizes the denaturation of proteins obtained by dimethyl having a different fat content than the original milk composi- ether extraction techniques. The contact time is the length of tion that is treated with phospholipase in the first step. A time that the dairy stream or dairy product is exposed to the food product according to the invention may be any food solvent at the near-critical conditions. In a preferred em- product wherein milk or one or more milk fractions may be bodiment of the invention, the dairy stream or dairy product used as an ingredient. In this way a combined milk fraction Patents in Dairy Sector Recent Patents on Engineering, 2014, Vol. 8, No. 1 47 with the desired composition and fat content may be pre- that the circumstances after the addition of the enzyme- pared, and such a combined milk fraction may have a differ- activating compound and before the addition of the acidify- ent content of phospholipid hydrolysis product than a similar ing agent, or in a reverse order, after the addition of the combined milk fraction that is treated with phospholipase acidifying agent and before the addition of the enzyme and after separation into fractions and subsequent mixing into a the enzyme-activating compound, do not change and/or are combined fraction. By mixing fractions of the invention into not changed in a manner causing the enzyme to become in- combined milk fractions it is thus possible to obtain com- active. In addition to these steps, the method of the invention bined milk fractions with a range of compositions and with preferably comprises any other necessary manufacturing novel and improved properties. steps for accomplishing the final product, such as the addi- tion of jam and/or sugar and/or heat- treatment (post- In the realization of dairy products it is also possible to pasteurization). Fermented or more generally soured fresh apply methods that modify the texture of a milk preparation. dairy products include yoghurts, viili, fermented milks, An application of this method is described in the patent WO quarks (a kind of low-fat curd cheese), fresh cheeses, cream 060288A1 [24] that relates to a method of manufacturing cheeses and soured cream products, such as cream frache sour milk preparations, such as soured fresh dairy products and smetana, for example. An advantage of the method of with the use of a transglutaminase enzyme, an enzyme- activating compound, and an acidifying agent by the addition the invention is that the amount of enzyme required in the thereof to a protein source under such circumstances that the method is smaller than the amount required when known methods are used. A smaller amount of enzyme required enzyme is active upon the addition of the acidifying agent results in clear cost saving in the production. Another advan- and/or during the acidifying. The method enables the modi- tage of the method according to the invention is that it en- fication of the texture of soured fresh dairy products more ables the utilization of raw material milk having a lower pro- advantageously and easily than known methods. In addition, tein content than in the use of the above-described, known the method enables a significant reduction in the protein con- methods. The method of the invention is suitable for the tent of soured fresh dairy products without any damage to or manufacture of flavored and non-flavored fatty and fat-free, adverse effect on the texture of the preparation. Convention- and homogenized and non-homogenized fresh products. It is ally, sour milk preparations have been manufactured by further suitable for the manufacture of lactose-free and low- acidifying milk with an acidifying agent at a suitable tem- lactose (such as HYLA®) products. perature. Before acidifying, all necessary raw materials (sweetener, flavoring agents and texture enhancer) are added CURRENT AND FUTURE DEVELOPMENTS to the milk, and the milk is then typically pasteurized and homogenized. The milk is acidified to a pH specific to each The mass consumption of milk and dairy products con- product. Then, the texture is broken for all products other tinually stimulates research and industries to suggest innova- than products of the viili type (ropy sour milk, a typical Fin- tions or create new products. In recent years, especially for nish milk product) and set-type yoghurts. Subsequently, nec- milk, has increased the range of products available and to the essary flavoring agents (e.g. jam addition) are added, and traditional milk (pasteurized, fresh pasteurized, micro- then the product is packaged. Conventionally, the dry sub- filtered, long-life) "special" milks were added consisting of stance content of milk is increased or decreased for adjusting milk deprived of some components (such as "lactose-free the texture of sour milk preparations. The protein content of milk") or enriched with vitamins and other substances (e.g. the raw material affects the texture of the final product in a calcium, proteins or probiotics) [25, 26]. As consumer de- manner allowing the texture of the sour milk preparation, mand continues to grow for high quality dairy products, fla- such as a soured fresh dairy product to be modified thicker vorful and not harmful to health, it is necessary to produce or runnier by increasing or decreasing the protein content. In dairy products with high health content. sour milk preparations, such as soured fresh dairy products (yoghurt, set-type yoghurt, viili, fermented milk), the use of The improvement of the competitiveness of dairy chain a transglutaminase enzyme serves to harden the texture, derives from both scientific and technological knowledge. In modify the texture to be finer, and thicker and to reduce syn- this context alternative methods of pasteurization that do not eresis. The patent also reports other inventions where the involve direct heat are being investigated in dairy sector in enzyme and the acidifying agent are added to the reaction order to obtain products safe for consumption, but with sen- mixture in different processing steps, and the enzymes, any sory attributes maintained as unchanged as possible [27]. processing aid affecting the activity of the enzyme or the These new techniques include high-pressure processing, acidifying agent, are not allowed to react simultaneously in pulsed electric fields (PEF), irradiation and carbon dioxide the mixture. Contrary to these previous inventions, the cur- injection [28, 29]. Among them, PEF has been reported to rent patent surprisingly discovered that the addition of both effectively reduce the numbers of both pathogens and spoil- transglutaminase enzyme and acidifying agent can be active age organisms in milk; however, there is a high degree of upon the addition of the acidifying agent and/or during the variability between studies, thus suggesting that further re- acidifying, thus resulting in a simpler method that requires search is still necessary to better assess the effects of PEF on fewer processing steps. The method according to the inven- milk and cheese. tion, wherein the cross-linking occurs during the acidifying, The need for extending the shelf life is another global is about 20% more effective compared with a method problem, affecting in a horizontal way the different subjects wherein transglutaminase enzyme alone is used during acidi- in the supply chain, from producers of packaging materials fying. 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