UNIT 11 RICE BASED PRODUCTS Structure 11.0 Objectives 11.1 Introduction 11.2 Breakfast Cereals 11.3 Rice Flakes 11.4 Puffed Rice/Paddy 11.4.1 Sand Puffing 11.4.2 Roller Puffing 11.4.3 Oil Puffing 11.4.4 Air Puffing 11.4.5 Gun Puffing 11.4.6 Extrusion Puffing . 11.5 Quick Cooking Rice 11,6 Fortified Rice 11.6.1 Rice Enrichment Processes 11.7 Rice Based Infant and Baby Foods 11.7.1 Pre-cooked Rice Cereal 11.7.2 Extrusion-cooked Baby Food 11.7.3 Formulated Baby Foods 11.8 Fermented Rice Products 11.8.1 Fermented Rice 11.8.2 Idli, Dosa and Dhokla 11.8.3. Ambai 11.9 Rice Noodles and Pasta 11.9.1 Traditional Method of Manufacturing Rice Noodles 11.10 Let Us Sum Up 11.11 Key Words 11.12 Some Useful References 11.13 Answers to Check Your Progress 11.0 OBJECTIVES After reading this unit, you should be able t~: • understand'the meaning of breakfast cereals; . • know different value added products produced from rice; • explain the steps for production of various rice based items; • know important consideration in the process technology; and • understand changes in nutrition value of the products. 89 Paddy Storage and Milling , Management 11.1 INTRODUCTION In India, due to growing urbanization of our society the demand for fast and convenience foods has increased. Rice is processed and reprocessed into numerous kinds of such foods. Process of rice depends on grain type and textural qualities for use in various kinds of prepared and convenient type rice products such as breakfast rice cereals" quick cooking rice, baby foods etc. Rice-based products that have been popular in India for a long time include rice flakes (poha avalakki>, popped, puffed or expanded rice, which are processed from rice or paddy; idJi, dosa, papads, vermicelli, crispies, muruku, etc., which are prepared from wet-ground rice paste or dry-ground rice flour; and fermented or deep-fried preparations made from a mixture of rice and pulses. 11.2 RICE BREAKFAST CEREALS Rice contains a large proportion of starch. In its natural form, the starch is insoluble, tasteless, andunsuited for human consumption. To make it digestible and acceptable it ml!st be cooked. Rice breakfast cereals may be divided into two classes: those which require cooking before serving and those which are ready-to-eat directly from the package. The ready-to-eat rice cereals may be made from entire rice grain or its milled products. In prepared cereals, rice, alone or in combination with other cereals, is precooked, dried, flaked or formed into dough, then expanded or puffed and toasted. The cooking time, steam pressure, temperature of the basic materials arid toasting procedure greatly influence the quality of the final product. Flouring materials, vitamin B complex, mineral and protein containing ingredients may be added to improve the nutritive value. Breakfast cereals can be categorized into types based on use (or) physical nature of the product: 1. Traditional cereals that require cooking- Cereals which are sold in the market as processed raw grains. 2. Instant traditional hot cereal- Cereals which are sold in the market as cooked grains and require only boiled water for preparation. 3. Ready-to-eat cereals- a group of cereals manufactured from grain products having \ been cooked and modified such that they may be subdivided into flaked, puffed or shredded products. 4. Ready-to-eat cereal mixes- Cereals combined with other grains, legumes or oil seeds and dried fruit products. 5. Miscellaneous cereal products- Cereal products which can not be included in any of the above types because of specialized process or end use. Cereal nuggets and baby foods are products which may be considered in this category. Check Your Progress 1 Note: a) Use the spaces given below for your answers. b) Check your answer with those given at the end of the unit. 1. List out the value added products from rice. 90 2. What are the important parameters affecting the final quality of processed product? Rice Based Products •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 0" •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• ~ ••• ................... ~ . 3. What are the different types of breakfast cereals? Describe briefly . ............ ..................................................................................................." ~ ......................................................................................... : . 11.3 RICE FLAKES In the traditional process, paddy is soaked in warm water overnight, the water is drained, and the soaked paddy is roasted in hot sand for I minute ana then hand pounded or passed repeatedly through an edge runner to get the kernels flattened. There is considerable loss in this process due to breakage of kernels during flaking. In the imp'roved technique, rice is first cooked in a rotary cooker at 8.2 to 8.6 kg/ern- pressure for 20 minutes and steam pressure is bled off to eliminate gases. Cooking is continue for I to 2 hours depending upon kind of rice used. In cooking rice it is necessary to add an agent that will prevent the cooked rice from sticking and forming lumps. Moisture after cooking should be about 33% and vacuum is applied after cooking to surface dry. After being dried to about 17 % moisture content, the cooked rice is tempered for several hours and then flaked on large smooth rolls and finally toasted. Thereafter, the blistered flakes are dried to 2-3% moisture content, cooled and packaged. The roller flakes are . used to eliminate the kernel breakage. Compared with oven-puffed rice, rice flakes tend to soften more quickly in milk. Check Your Progress 2 Note: .a) Use the spaces given below for your answers. b) Check your answer with those given at the end of the unit. 1. Describe the traditional method of preparation of flaked rice. 2. Describe the improved method of preparation of flaked rice and indicate the major difference over traditional method . ........................ .' . 11.4 PUFFED RICE . Puffed rice is very popular in India as a low cost ready-to-eat breakfast cereal as well as snack because of its crispness and lightness. It is also a favourite food product made in different forms like puffed rice balls, bars and fatty pastes, chocolate (or) boiled sugar confectioneries in many countries. 91 Paddy Storage and Milling Puffing of rice grains results from the sudden expansion of water vapour (steam) in the Management interstices of starch granules during high-temperature-short-time (HTST) heating of the grains. The particle is fixed in its expanded state by the dehydration resulting from the rapid diffusion of the water vapour out of it. Puffed product should be maintained around 3 percent moisture in order to achieve the desired crispness. Puffing processes may be broadly classified into two groups: 1) atmospheric pressure processes which rely upon the sudden application of heat to obtain the necessary rapid vaporization of water, and 2) pressure drop processes which consists of suddenly transferring superheated particles into a space at lower pressure. The pressure drop may be achieved by releasing the seal on a yes el containing a product, which ha been equilibrated with high temperature steam or it may be secured by transferring the hot material from the atmosphere into an evacuated chamber. Sand puffing, air puffing, oil puffing, roller puffing and oven puffing are examples of atmospheric pressure processes while gun puffing, extrusion puffing are examples of pressure-drop processes. 11.4.1 SandPuffing . This method is traditionally followed in India where parboiled rice grains having initial moisture content of 11-12 percent are mixed with 2 percent salt and limited water so that / moisture content of rice increases upto 16-29 percent (wb), Moistened rice grains are heated (tempering) for 30 minutes to 8 h for moisture equilibration within the grains. The treated rice grains are dried in the bright sun or by conduction heating in a hemispherical metallic container with continuous stirring until grains get dried upto 10 to 11 percent (wb). Small quantity of the rice is roasted at an optimum sand temperature between 230 to 275 QCfor 6 to 20 seconds to give puffed rice with expansion ratio of 8 to 10. The process is tedious and the production capacity is very low (2-2.5kg/hr). 11.4.2 Roller Puffing , In roller puffing, dough with moisture content of 8 to 18 percent is fed into the rolls with temperature of 190 to 440Q C. Puffed products are obtained at 6 to 7 % moisture content. The rolls are heated by radiant heat or by circulation of high temperature fluid media inside the cylinder. 11.4.3 Oil Puffing Pre heated rice (parboiled) is puffed in vegetable oil at 200 to 220 QCtogive expansion ratio of 5 to 7. 11.4.4 Air Puffing Blast of air at 200 to 300 QCfor 7 to 10 seconds is given to pretreated rice at IOta 12O/~ moisture content which gives puffed rice with expansion ratio of 8 to 10. 11.4.5 Gun Puffing In this process raw milled rice and other grains can be puffed and do not need pretreatment (parboiled) before puffing which is an essential step for puffing with other technique. Pro-moistened pearled or unpearled grains are fed into a pressure vessel, which is continuously rotated and externally heated. As the optimum pressure, varies from grain to grain, the sudden release of chamber pressure causes the superheated water to flash into steam resulting in porous structure of the puffed products. In some cases preheated grains at 272-337 "C (521 to 638 OF) are fed to the pressure vessel in which pressure is built by superheated steam upto 15.1 kg/ern" at a temperature of 241.6 QCat the gun. After a short cooking time, the gun is suddenly opened to produce puffed rice.