s\ — Illl INI II llll II II llll III II I II OJII Eur°Pean Patent Office <*S Office europeen des brevets (11) EP 0 940 090 A1 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: (51) |nt. CI.6: A23L 3/3508 08.09.1999 Bulletin 1999/36 (21) Application number: 98204480.2 (22) Date of filing: 30.12.1998 (84) Designated Contracting States: (72) Inventor: Philipp, Gert Dieter AT BE CH CY DE DK ES Fl FR GB GR IE IT LI LU 21423 Winsen (Luhe) (DE) MCNLPTSE Designated Extension States: (74) Representative: AL LT LV MK RO SI Vuille, Roman et al Avenue Nestle 55 (30) Priority: 27.02.1998 US 76403 P 1800 Vevey (CH) (71) Applicant: SOCIETE DES PRODUITS NESTLE S.A. 1800 Vevey (CH) (54) Process for preserving food products (57) A process for the manufacture of food products which have been preserved under mild conditions, which includes a treatment of a food to kill microorgan- isms and their spores in a manner which is mild for the food by adding to the food a combination of (i) at least one sodium salt of a lipid-soluble, optionally hydroxy- substituted, C2 or C3 fatty acid and (ii) at least one non- lipid-soluble acidulant which has a pKa below that of the C2 or C3 fatty acid and which forms complexes with doubly charged alkaline earth metal ions, optionally with (iii) additional amounts of a sodium salt of the acidulant in an amount such that the pH of the food is in the range of about 4.5 to 7, and the concentration of undissociated fatty acid is at least 0.4% by weight based on the weight of the food. No thermal sterilization is necessary for preservation; on the contrary, a final thermal treatment with less than pasteurization conditions is sufficient. < O <7> O O <7> O Q_ LU Printed by Xerox (UK) Business Services 2.16.7/3.6 1 EP 0 940 090 A1 2 Description germinative spores are no longer detectable in acidic preserves 2 to 4 weeks after a heat treatment under Background Of The Invention pasteurization conditions. [0005] Investigations of the effects leading to destruc- [0001] The present invention relates to a process for s tion of bacterial spores (thermally resistant endospores) the manufacture of food products that have been pre- at acidic pH values revealed that the compound calcium served under mild conditions. The process includes dipicolinate, which was detected in spore capsules and treatment of the food products to kill microorganisms is thought to be responsible for their thermal resistance, and their spores therein. The resulting food products is converted in the aqueous acidic medium into the are preserved by application of the process to have high w water soluble compound, dipicolinic acid. The latter is microbiological stability and no more than a minimal washed out of the spore capsule, which then takes up impairment of their valuable constituents. water and swells. Undissociated lipid-soluble acids such [0002] To manufacture various packaged food prod- as acetic acid, lactic acid or propionic acid are able to ucts, it is necessary to confer thereon a microbiological enter the spores through the swollen spore capsule and stability for at least the period of time regarded as the is have a lethal effect inside the spore or the vegetative use-by period which is customary for the particular food. cell formed therefrom. This is why pasteurization of There are numerous processes for preserving food acidic foods is sufficient to lead to complete microbio- products, and they can be generally divided into those logical stability of such foods. in which preservation is achieved by (1) changes in tem- [0006] Those skilled in the art were informed by the perature (blanching, pasteurization, sterilization, cold 20 inventor in the article " Dauerhaft frisch ohne Kuhlpfli- " storage, frozen storage), (2) removal of moisture (dry- cht" in the publication Die Ernahrungsindustrie" , 3/97, ing, freeze-drying, brining, salt pickling, sugaring), (3) pages 54/55, that it is possible for foods requiring steri- the addition of preservatives (smoking, use of alcohol or lization to be lastingly preserved even at a pH range of food preservatives), (4) acidification (acid pickling), (5) 4.5 to 7 under pasteurization conditions when a different removal or exclusion of oxygen, or (6) irradiation. 25 route is followed to make the insoluble calcium dipicoli- [0003] Processes of particular importance for prod- nate soluble and thus remove it from the spore capsule. ucts that have a high moisture content, especially liquid A need for lastingly preserving foods sterilized exclu- or pasty foods and preserves with a liquid phase, are sively by pasteurization, however, still exists. those which conduct pasteurization or sterilization and acid pickling treatments. Pasteurization refers to a heat 30 Summary of The Invention treatment of thermosensitive preferably liquid or pasty foods at temperatures below about 1 00°C with the aim [0007] The present invention relates to a process for of killing all unwanted vegetative microorganisms. lastingly preserving neutral or slightly acidic foods that Under the usual pasteurization conditions, however, have a pH of about 4.5 to 7 without the need for conven- spores of all microorganisms are normally not inacti- 35 tional sterilization conditions, thus avoiding treatment vated or killed, and thermoduric bacteria also some- temperatures that are above 100°C for lengthy times. times survive this treatment. In order to kill all the [0008] This process includes treatment of such food microorganisms present in a food product, including products to kill microorganisms and their spores in a bacterial spores, in order to prepare the so-called sterile manner which is mild for the food product by adding preserves, high temperatures distinctly above 100°C 40 thereto a combination of (i) at least one sodium salt of a over a lengthy period (for example 1 20°C maintained for lipid-soluble, optionally hydroxyl-substituted, C2 or C3 30 minutes) are necessary for neutral pH packaged fatty acid and (ii) at least one non-lipid-soluble acidulant foods. Although such sterilization conditions render the which has a pKa below that of the C2 or C3 fatty acid spores therein harmless, there is also damage to and which forms complexes with doubly charged alka- numerous constituents which determine the nutritional 45 line earth metal ions, and optionally (iii) additional value of the food, such as vitamins, macro- and micro- amounts of a sodium salt of the acidulant in such minerals, coloring matter and flavors, or supporting and amounts and ratios of amounts so that the pH of the texturing substances. Thus, foods obtained by the usual food product is in the range of about 4.5 to 7, and the thermal sterilization treatment are to be regarded as concentration of undissociated fatty acid is at least 0.4% being more damaged than fresh foods. so by weight based on the weight of the food product. Pref- [0004] A thermal sterilization treatment at tempera- erably, these additives are incorporated in the food tures distinctly above 100°C has proved to be unneces- products in concentrations of at least 0.5% by weight for sary when the food which is desired to be sterile is an the fatty acid salt and at least 0.2% by weight for sodium acid-pickled food whose pH is below 4.5. This is ions, the percents being based on the weight of the food because it has been found that, in contrast to neutral 55 product. foods, bacterial spores in foods having a pH below 4.5 not only do not germinate but are also subject to altera- tions which eventually lead to their destruction. Thus, 2 3 EP 0 940 09090 A1 4 Detailed Description of the Preferred Embodiments The acidulant used in combination with the sodium salt acts as proton donor. Because of its higher acidity, the [0009] The sodium salt of a lipid-soluble fatty acid presence of the acidulant results in higher concentra- which is preferably employed as the first component is tions of undissociated fatty acid, that is to say undisso- the sodium salt of acetic acid, sodium acetate. It is also s ciated acetic acid or, where appropriate, lactic acid or possible for the sodium salt of lactic acid, sodium lac- propionic acid, than is normally found at pH values tate, to be used instead. The use of a sodium salt of pro- above 4.5. A preferred buffer system may be used to pionic acid likewise appears possible, especially in keep the pH in the range of from 4.5 to 7. A preferred countries where propionic acid is approved for the pres- buffer system is one based on the acidulant used, par- ervation of foods. 10 ticularly of a sodium salt of this acidulant. [0010] Where reference is made in the present appli- [001 3] When this combination of substances is added cation to C2 and C3 fatty acids, this term refers to to a food having a pH of 4.5 or more and containing unsubstituted acetic and propionic acids as well as spores of microorganisms such as thermally resistant hydroxy derivatives of these acids, and especially lactic endospores, an environment is set up in the food that acid. is causes the spores to germinate. These germinated [0011] The second component used is a solid acidu- spores can be killed thermally, under pasteurization lant which is not lipid-soluble, has a pKa below that of conditions, or with the aid of the undissociated fatty acid the fatty acid underlying the sodium salt employed, and which migrates into the microorganisms.