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Product Category: Projects
Product Code: 00007244
No of Pages: 86
No of Chapters: 5
File Format: Microsoft Word
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ABSTRACT
The Scarcity of milk supply in developing countries perhaps led to the development of alternative milk from vegetable sources in Nigeria. The aim of this study was to produce yoghurt from blends of rice milk and soy milk and evaluate their proximate composition, mineral content, physico-chemical properties, microbiological quality and sensory properties using standard methods. The results obtained for proximate composition revealed the following range of values for moisture (
TABLE OF CONTENTS
Title Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgments v
Table of Contents vi
List of Tables ix
List of Figures x
Abstract xi
CHAPTER 1: INTRODUCTION 1
1.1 Background of the Study 1
1.2 Statement of Problem 5
1.3 Justification 7
1.4 Objective of Study 9
CHAPTER 2: LITERATURE REVIEW 10 2.1 Milk 10
2.1.1 Importance of milk and milk products 10
2.1.2
Fermented milk products 11
2.2 Yogurt 13
2.2.1 History of yogurt 15
2.2.2
Nutritional value of yogurt 18
2.2.3
Quality and shelf-life of yogurt 18
2.3
Vegetable Milk 19
2.3.1 Soybeans
and soymilk 20
2.3.1
Soy-yogurt 22
2.3.3 Milk
preparation and heat treatment 23
2.4
History and
Consumption of Soy Foods 24
2.4.1 Nutritional benefits of soy foods 26
2.5
Rice 27
2.5.1
Rice milk and rice yogurt 28
2.5.2
The nutritional value
of rice milk 29
CHAPTER 3: MATERIALS AND METHODS 31
3.1 Materials and Starter Cultures 31
3.2 Preparation of Rice Milk 31
3.3 Preparation of Soymilk 30
3.4 Rice-Soya Yogurt 31
3.5 Determination of Proximate Analysis 32
3.5.1
Moisture content 32
3.5.2 Nitrogen distillation 34
3.5.3
Total ash 34
3.5.4 Carbohydrates 36
3.5.5 Crude fat 36
3.6 Physiochemical Properties 38
3.6.1
pH measurement 38
3.6.2
Titratable acidity 38
3.6.3
Total solids 38
3.6.4
Solids-not-fat 39
3.6.5
Specific gravity 39
3.6.6
Milk solid non-fat (MSNF) 39
3.6.7
Mineral elements 40
3.6.8
Refractive index
40
3.6.9
Total aflatoxin analysis 40
3.6.10 Viscosity 41
3.7
Microbiological
Analysis 41
3.8
Sensory Evaluation 42
3.9
Statistical
Analysis of Data 42
CHAPTER 4: RESULTS AND DISCUSSION
4.1 Proximate
Composition of Yogurt Produced from Blends of Rice Milk
and Soymilk 43
4.2 Physico-Chemical Properties of Yogurt Produced from blends of
Rice
Milk and
Soymilk 46
4.3 Mineral Content of Yogurt Produced from blends of Rice Milk
and
Soymilk 50
4.4 Microbiological
Quality of Yogurt Produced from blends of Rice Milk
and Soymilk 53
4.5 Sensory Evaluation of Yogurt Produced from blends of Rice Milk
and
Soymilk 55
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS 58
5.1 Conclusion 58
5.2 Recommendations 58
References 59
LIST OF TABLES
4.1: Proximate composition of rice-soymilk
yogurts 45
4.2: Physico-chemical properties of rice-soymilk
yogurts 49
4.3: Mineral content of rice-soy milk yogurts 52
4.4: Microbial load (CFU/ml) of rice-soy milk
yogurts 54
4.5: Sensory attributes of rice-soy milk yogurt 57
LIST OF FIGURE
1: Flowchart of rice soya yoghurt production 33
CHAPTER ONE
INTRODUCTION
1.1
BACKGROUND OF STUDY
In the past few decades, extensive studies of lactic acid fermentation of cereal and Legume have been researched. Extruded rice flour, liquefied starch and cooked maize meal mixture are types of yoghurt-like product produced from different kind of cereals. (Shin, 1989; Lee et al., 1992; Zulu et al., 1997). A product, so called Risogurt, was produced from mixture of fermented rice and soy protein isolate (Mok et al., 1991). Mok et al., (1993), the further developed a method for producing a highly concentrated lactic product from rice with improved quality by a secondary enzymatic treatment during fermentation.
In 2010, there are about nine hundred and twenty nine million people in the world who were affected by starvation with two hundred and thirty nine million from sub-Saharan African. The most victims were the children and the vulnerable groups. Deficiency of Protein calorie which is the most deadly form malnutrition could be resolved if people could have daily access to cost effective and balanced nutrition on their table.
The normal life of human may be extended to twice of 70 years, if people will learn how to introduce a suitable flora in the intestine of children as soon as they are weaned from the breast.” That rather statement by Metchnioff (1921) has arguably never been achieved because there is no report to date that human can normally live up to 140 years. However, the statement emphasizes maintaining balanced intestinal flora to have a healthy life. More than few decades the market for fermented dairy Yoghurt, has increased appreciably along with the steadily increasing knowledge of the health benefits for fermented dairy products.
Semi-fermented dairy milk food, example yoghurt is preferred and consumed by people all around the world. The possible use of fermented dairy food is to prevent/control diarrhea because of its therapeutic effect. The inflammatory response by carcinogen through increasing apoptosis is modulated by the help of the food. Yoghurt protein is more digestible than cow milk (Belewu et al., 2005). Yoghurt can be defined simply as a dairy product from fermentation of milk. This fermentation produces lactic acid from lactose that, combined with milk protein, gives yoghurt its characteristic acidic taste and texture. Yoghurt is further defined in the United States as an acidic-gelled product from culturing of cream milk, partially skim milk, or skim milk either alone or in combination by Streptococcus thermophilus and Lb. delbrueckii subsp. bulgaricus. Other ingredients and other additional ingredients, and the micro-organisms used must remain viable in the end product (FSANZ, 2007).
The type and characteristics of micro-organisms used as starter cultures for milk fermentation are two of the most essential factors that determine the overall quantity of the fermented products (Bouzar et al., 1997). A proper selection and composition of starter culture can improve the product flavor, aroma, stability, and texture. Therefore, it is significant to understand the characteristics of the starter bacteria to obtain desirable, quality products.
The microorganisms used in milk fermentation can be categorized into three groups: Mesoph8ilic, Thermophilic, and Artisanal. The optimum temperatures for the first two groups are approximately 26˚C (79˚F) and 42˚C (108˚F) respectively, and they consist of different species of bacteria. The artisanal who consumed yoghurt regularly in its native Balkan regions lived longer (Metchikoff 1921, Van de water 2003). This knowledge of health benefits of yoghurt has helped to increase yoghurt consumption. The trend is also enhanced by the increased palatability of yoghurt due to the addition of sweeteners and fruits (Van de water 2003). Yoghurt is usually made through fermentation by thermophilic microorganisms at a relatively high temperature (slightly higher than 45˚C; 113˚F) (Walstra et al., 2006) and a shorter fermentation time (5 hours or longer) at which the maximum pH of 4.5 is used as a guide to stop the fermentation. Therefore, this limitation is used to distinguish yoghurt from other fermented milk products. The term yoghurt is also used to cover strained products from thermophilic fermentation of milk such as yoghurt cheese, greek yoghurt and other yoghurt with cheese-like textures that retain the acidic characteristics of yoghurt. Milk fermentation culminates in a product with different textures ranging from liquid such as kefir and koumis to semi-solid or solid such as yoghurt (Van de water 2003). Fermentation of milk with lactic Acid Bacteria (LAB) also results in products with characteristic tastes and aromas. LAB metabolism and interaction between selected strains produces lactic acid and other compounds as well as coagulates milk protein. Fermentation conditions such as temperature, pH, the presence of oxygen, and milk composition also contribute to the characteristics of the end product (Nakazawa and Hosono1992).
The continued dairy milk shortage or absence in the developing countries, therefore had led to the production of milk substitutes from vegetable. Development of milk substitute generated from cereals and legumes provide an alternative ways of producing an acceptable nutritious food based on vegetable is increasing (Harkins and Sarret 1967).
Vegetable milk (analogue milk or plant milk) is a general term for any non-dairy cream analogue that is derived from a plant source (http://www.en.wikipedia/plantmilk,2015). No formal or legal definitions for vegetable milk exist in most countries. The most common varieties are soy milk, oat milk, coconut milk, but there are also other varieties available which are rice or nut based. Severe diseases like PKU, makes animal proteins (especially casein) found in dairy milk difficult to digest are diverse reasons that lead to the consumption of vegetable milk (approximately 3% of people are allergic) (http://www.foodintol.com/dairy.asp,2015).
Vegetable milk can be used for babies in communities where babies are not given dairy milk for ethical reasons and galactosemia (Obizoba and Egbuna 1992). Communities where babies are not given dairy milk for ethical reasons and galactosemia are feed with vegetable milk (Obizoba and Egbuna 1992). The most common legume and cereal grain, soybeans and rice will be used alternatively as a milk substitute in the production of yoghurt. Improvement of quality soymilk are still researched (Sun-young et al., 2000) but rarely on rice milk. Therefore in this study, rice milk will be substituted with soymilk to produce yoghurt in order to complement its nutrient deficiency. The sweet taste in most rice milk varieties are produced by a natural enzymatic process, generating sugars by the cleavage of carbohydrates, especially glucose similar to the Japanese amazake (http://www.bnet.com/ricemilk). Some rice milk may nevertheless be sweetened with sugar cane syrup or other sugars. Rice milk contains more carbohydrate, but does not contain significant amounts of calcium, vitamin B12, vitamin B3 and iron compared to cow’s milk. It is often consumed by people who are lactose intolerant, allergic to soy or have PKU. It is also used as dairy substitute for vegetarians, and rice milk does not contain cholesterol or lactose (http://www.en.wikipedia/wiki/ricemilk).
Soymilk is a fine emulsion of soybeans flour or water extract of wet ground soybean. Among the sources of vegetable milk, soybean has received high research attention and more research is still designed to improve the quality of soymilk (Sun-young et al., 2000). Though the soybean is classified among the leguminous plants, it differs from other legumes in containing far more proteins and fats than ordinary peas and beans.
Emphasizes of scientific studies concludes the fact that soybean contains vitamins in substantial quantities and is a valuable source of B-complex vitamins. Soya beans protein contains essential amino-acids and is therefore a complete protein which satisfies the human requirements for protein metabolism. Soya milk is a complete protein and has about the same protein as cow’s milk; it can substitute animal protein and other sources of dietary fiber, vitamins and minerals (Sack et al., 2006). Soymilk contains little digestible calcium because calcium is bound to the bean’s pulp, which is indigestible by humans. Soymilk has little saturated fat and no cholesterol compared to cow’s milk.
Sucrose seen in soy products as basic disaccharide, are broken down into glucose and fructose. Since soy does not contain galactose, a product of lactose breakdown soy-base formulas can safely replace breast milk in children with galactosemia. Soy milk contains no lactose, which makes it a substitute for those who are lactose-intolerant. The composition of soymilk varies with the varieties of soybean used and the method of production (Wang et al., 1978).
Soyfoods, especially soymilk, are considered a good substitution for dairy products for individuals who have milk intolerance. Prior to the development of such vegetable milk like soymilk which serve as an alternative milk substitute for dairy milk, direct milk consumption as a beverage was not common in Nigeria (Iwuoha and Umunnakwe 1997; Onweluzo and Owo 2005). Milk intolerance including cow’s milk protein allergy (CMPA), cow’s milk protein intolerance (CMPI), and lactose intolerance is prevalent in the world, especially in children. CMPA can affect from 2 to 6% of children. Studies have shown that 80% to 90% of these children will resolve CMPA within their fifth year (Host et al., 2002; Wood 2003; Goplan 2011). The important and widely used method used for treating milk intolerance is the exclusion of all forms of animal milk and milk products from the diet. Because of the high plant protein content and similar texture as milk, soymilk is a healthy protein source for those milk intolerant individuals. In addition, cow’s milk contains saturated fats that might increase the risk of cardiovascular diseases (Siri-Tario et al., 2010; Astrup et al., 2011). Soymilk which contains much lower amounts of saturated fat than cow’s milk could be a good choice for individuals who are concerned about heart disease. Dairy milk which contains high quality protein and other nutrients is essential for the well- being of an individual, for some reasons not consumed by all, due to health conditions such as inability to digest milk sugar-lactose, milk allergy, and PKU. Casein, a protein found only in milk, contains all of the essential amino acids and accounts for 82% of total proteins in milk are indigestible by some individuals due to this factor, milk from vegetable sources was developed as an alternative means of milk consumption.
Although soymilk and soyfoods are nutritious and their consumption has many health benefits, soymilk has some limitations such as beany flavor, possible allergic reactions and undesirable microbial fermentation after intake by some consumers. Consequently, scientists have tried to resolve these problems by creating some new lines of soybeans for instance, low and ultra-low raffinose family oligosaccharide soybeans, lipoxygenase free soybeans, high oleic soybeans, low P34 allergen soybeans, and high sucrose soybeans. It would be of great interest to know if soybeans could address these problems. This has not been reported in literature (Jing, 2013).
In Nigeria, rice (Oryza spp) is a vital staple food consumed by many people. It is the most important food crop in the world, being the staple food for more than half of the world’s population, predominantly in Asia and Africa where more than 90% of the world’s rice is grown and consumed. It is a very versatile crop and there are many varieties of rice adapted to various environments and cultivation practices (Luc et al., 2010). However, adoption (utilization) of innovations is a very important tool in measuring the effectiveness and efficiency of agricultural products. Its varieties of preparation and use will enhance the appeal for consumption.
1.3 JUSTIFICATION
Historically, fermented foods have played important role in diets of most people in every society throughout the world. But beyond just the culinary choices and preservation, advantages of fermented foods is the natural phenomenon of fermentation performed by the cells within our bodies that help to keep us healthy. The reasons for fermenting milk are numerous and although the primary function is to extend its shelf-life, other advantages, such as improving the taste of milk, enhancing the digestibility of the product and the manufacture of a wide range of products (i.e. from yoghurt to concentrated yoghurt to cheese) should not be overlooked. A health aspect attributed to special probiotic micro-organisms used in fermented milks and other dairy products will not be covered in these publications, as they are included in probiotic dairy products within the technical series prepared on behalf of the society of dairy technology (SDT) in the UK (Tamime, 2005). In lacto-fermentation, lactobacillus bacteria have the ability to convert sugar into acid through a naturally occurring fermentation process. It is a natural preservative that inhibits the growth of harmful or putrefying bacteria. This phenomenon allowed people to preserve foods for extended periods of time before the advent of refrigeration or canning. Lactic acid promotes the growth of healthy bacteria in the intestinal tract. That is why fermented foods are considered probiotic foods (Probiotic means “for life”). Beyond preservation advantages, lacto-fermentation also increases the vitamin and enzyme levels, as well as digestibility, of the fermented food. Several range of micro-organisms have been used in food and beverage preparations for thousands of years by humankind and, according to Tamime (2002), the major functions of microbial starter cultures in either food or other dairy products may be summarized as:
- To bio-preserve the product due to fermentation that results in an extended shelf-life and enhanced safety;
- To produce bacteriocins that may have potential uses as food preservatives;
- To enhance the perceived sensory properties of the product (e.g. due to the production of organic acids, carbonyl compounds and partial hydrolysis of protein and/or fat);
- To improve rheological properties of fermented milk products (i.e. viscosity and firmness);
- To contribute dietetic/functional/nutraceutical properties of fermented milks, such as occurs with the use of probiotic micro-organisms.
Yoghurt is semi-fermented milk consumed by people all over the world. It is classified into different types and variations probably due to the various types of live and active culture used, plain or fruit flavor and most importantly the different sources of milk (animal/plant) (Belewu et al., 2005; Belewu, 2006). Rice milk is considered the best hypoallergenic form of milk. The milk enhances immune system and provides resistances to bacteria and viruses invading the body due to high level of antioxidant, selenium and magnesium (http://www.healthiro.com/diet.food/rice-milk).
A wide range of fermented milks are manufactured throughout the world and, according to Kurnmann et al., (1992), around 400 generic names are applied to traditional and industrialized products. In UK, for an example, the economic value of yoghurt and drinking yoghurt sold in 2002 was around £814 million. (Anon, 2003). For those people who cannot or do not want to consume dairy yoghurt. Rice-Soya yoghurt might be an acceptable replacement considering the low protein content in rice milk; rice milk will be complemented with soy milk which contains same amount and quality protein as that in cow’s milk (Sacks et al., 2006) in the production of yoghurt. Therefore, properties of rice- soya yoghurts made from rice milk and soy milk are tested because texture and mouth feel are the most important characteristics for yoghurts.
1.4 OBJECTIVE OFSTUDY
The main objective of this research is to produce yoghurt from locally available raw materials from rice milk and soymilk.
The specific objectives of the research are to:
i. To produce plant yoghurt from rice milk and soymilk.
ii. To evaluate the physicochemical properties of rice-soy yoghurt.
iii. To determine mineral contents of the rice-soy yoghurt.
iv. To evaluate its general acceptability.
v. To carryout microbial analysis on the yoghurt samples.
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