Nutritional improvement of soy flour

Heating soy flour at 45 degrees C in pH 8.5 Tris buffer for 1 hour in the presence of cysteine or N-acetylcysteine followed by dialysis to remove unreacted thiols resulted in the introduction of new half-cystine residues and lowered trypsin inhibitor content from 37.5 to 6.8 or 4.8 mg/g, respectively, compared to only 14.8 mg/g in the absence of sulfhydryl compounds. Presence of cysteine or N-acetylcysteine during treatment increased protein efficiency ratio (PER) from 0.95 to 2.01 or 2.20, respectively. Corresponding values at 65 degrees C are 1.61, 2.43 and 2.02; and at 75 degrees C, 2.14, 2.53 and 3.19, respectively. Proteins are modified through formation of mixed disulfide bonds, which leads to loss of inhibitory activity and increased protein digestibility and nutritive value.     

Nutritional benefits of soy protein and soy fiber.

Soy protein and soy fiber are common ingredients in many foodstuffs. Various kinds of soy protein, including soy flour, soy-protein concentrate, and isolated soy protein, are currently used in human foods. Soy proteins are used in infant formulas and enteral nutrition products, as ingredients in meat products, and as protein supplements. Although it is a plant protein, the protein quality of soy protein is excellent. Soy fiber is used in enteral nutrition products and some bakery goods. Research shows that soy fiber provides the important health benefits usually associated with dietary fiber, including improved laxation and cholesterol-lowering ability. This review provides background information on soy protein and soy fiber and their use in human foods.     

Effect of sulfur amino acid supplementation of raw soy flour on the growth and pancreatic weights of rats

Rat feeding studies showed that L-cystine, L-cysteine, N-acetyl-L-cysteine and L-methionine enhance the nutritional quality of raw (unheated) soy flour as measured in rats by the protein efficiency ratio (PER). Pancreas weights of rats fed diets supplemented with sulfur amino acids were higher than those of rats fed unsupplemented diets. In some instances this increase resulting from nutritional improvement of the diet was relatively greater than that in total body weight. Explanations are offered for these effects in terms of the proposed biofeedback mechanism involving the gastrointestinal endocrine system and the hormone cholecystokinin. The observed stimulation of pancreatic growth by added sulfur amino acids may be closely associated with this pancreatic regulatory mechanism when activated in response to dietary trypsin inhibitors present in unheated soy protein. The extent to which pancreatic hypertrophy develops as a result of a given exposure to trypsin inhibitors may be limited when the total amount or quality of the protein in the diet is less than optimal.     

Nutritional study of spun soy proteins

Most of metabolic studies in man concerning the ability of soya proteins to obtain an equilibrated nitrogen balance have been made with extruded products. Because of the extending development of spun proteins, it seems necessary to study the protein quality of this type of product. A preliminary study in rat (C.E.P. method) was conducted to improve the nutritional value by complementation of the fibers by the way of binder. The metabolic utilization of this protein was evaluated in human subjects during two periods of 10 days. Soya protein cover respectively 78 and 48% of the total protein intake. Under these experimental conditions in which soya proteins constitute an important percentage of the total protein intake, the mean nitrogen balance is near to be equilibrated and the nitrogen utilization does not present any significative difference between the periods. Parallely to the suppression of animal proteins, the introduction of insatured lipids in the diet, has allowed, moreover, to decrease the concentration of the lipidic parameters of the subjects. This study demonstrated the dietetic interest and the ability of the studied product to provide the supplying of the nitrogen balance.     

Dietary soy protein attenuates renal disease progression after 1 and 3 weeks in Han:SPRD-cy weanling rats

Compared with casein, dietary soy protein slows disease progression in animal models of chronic renal injury. To determine whether dietary soy protein feeding can alter early disease progression, male Han:SPRD-cy rats (n = 87) in a very early stage of chronic kidney disease were fed soy protein compared with casein-based diets for 1 or 3 wk. Kidneys were assessed for fibrosis, cyst growth, fatty acid composition and prostaglandin E(2) (PGE(2)) production. Soy protein feeding significantly reduced renal fibrosis by 22% (P = 0.0347) and 38% (P = 0.0102) after 1 and 3 wk of diet, and cyst growth was 34% lower after 3 wk (P < 0.0001). Kidney 18:2(n-6) levels were reduced in normal and diseased rats after as little as 1 wk of consuming the soy protein diet. Dietary soy protein also partially ameliorated the suppression of PGE(2) production observed in diseased kidneys. Compared with diseased kidneys from casein-fed rats, ex vivo PGE(2) release was 31-32% higher after 1 (P = 0.0281) and 3 (P = 0.0189) wk of dietary soy protein consumption. Hence, the first signs of a beneficial soy protein effect were observed after 1 wk of feeding, with further improvements evident after 3 wk. These data demonstrate that dietary soy protein compared with casein delays disease progression in an early stage of chronic kidney disease.     

Nutritional and technological evaluation of an enzymatically methionine-enriched soy protein for infant enteral formulas

Enzymatically modified soy proteins have the amino acid profile and functional properties required for dietary support. The objective of this study was to evaluate the nutritional and technological properties of an enzymatically modified soy protein ultrafiltered fraction with bound methionine (F(1-10)E) to be used as a protein ingredient for infant enteral formulas. F(1-10)E was chemically characterized and biologically evaluated. Thirty-six weaning Wistar rats were fed during 3 weeks with a 4% casein-containing diet. Rats were divided into three groups and recovered for 3 weeks with 18% protein-containing diets based on: (1) F(1-10)E, (2) casein or (3) soy isolate+methionine. Nutritional indicators were weight gain, protein efficiency ratio, plasma proteins, apparent digestibility and protein in the carcass. Additionally, F(1-10)E was added as a protein ingredient of an enteral formula, and its sensory and rheological properties were compared with a hydrolyzed-whey protein commercial formula. F(1-10)E contained 68% protein and 5% sulphur amino acids, with 60% of peptides 0.05) in weight gain (108 g and 118 g, respectively), protein efficiency ratio (2.7), apparent digestibility (93% and 95%), plasma proteins (5.7 mg/100 ml) and carcass protein (61%), and better than soy isolate-based+methionine diet (P<0.05). Viscosity of the commercial formula and our formula was similar during a 24-h period. Sensory acceptability was 8 for our formula and 3.5 for the commercial one, on a scale of 1-10 (P<0.05). Due to its nutritional, sensorial and rheological properties, F(1-10)E could be used as a protein source in infant enteral formulas.     

Nutritional aspects of cereals

SUMMARY 1 INTRODUCTION 1.1 General structure of grains 1.2 Wheat 1.3 Rice 1.4 Maize 1.5 Barley 1.6 Oats 1.7 Rye 1.8 Millet 1.9 Sorghum 1.10 Triticale 1.11 Other grains 1.12 Key points 2 TECHNICAL ASPECTS OF CEREALS 2.1 Cereal production 2.2 Storage 2.3 Processing 2.4 Cereals and food safety 2.5 Key points 3 THE ROLE OF CEREALS IN HEALTH AND DISEASE 3.1 History of cereals in diet 3.2 Nutritional value of cereals 3.3 Contribution of cereals and cereal products in the diet 3.4 Cereals in health and disease 3.5 Labelling and health claims 3.6 Consumer understanding 3.7 Key points 4 FUTURE DEVELOPMENTS 4.1 Fortification 4.2 Genetic modification 4.3 Gene–nutrient interactions 4.4 Key points 5 CONCLUSIONS AND RECOMMENDATIONS REFERENCES GLOSSARY

Summary

Cereals are the edible seeds or grains of the grass family, Gramineae. A number of cereals are grown in different countries, including rye, oats, barley, maize, triticale, millet and sorghum. On a worldwide basis, wheat and rice are the most important crops, accounting for over 50% of the world's cereal production. All of the cereals share some structural similarities and consist of an embryo (or germ), which contains the genetic material for a new plant, and an endosperm, which is packed with starch grains. After harvest, correct storage of the grain is important to prevent mould spoilage, pest infestation and grain germination. If dry grains are held for only a few months, minimum nutritional changes will take place, but if the grains are held with a higher amount of moisture, the grain quality can deteriorate because of starch degradation by grain and microbial amylases (enzymes). Milling is the main process associated with cereals, although a range of other techniques are also used to produce a variety of products. Slightly different milling processes are used for the various grains, but the process can generally be described as grinding, sifting, separation and regrinding. The final nutrient content of a cereal after milling will depend on the extent to which the outer bran and aleurone layers are removed, as this is where the fibre, vitamins and minerals tend to be concentrated. There is potential for contamination of cereals and cereal products by pests, mycotoxins, rusts and smuts. Recently, acrylamide (described as a probable carcinogen) has been found in starchy baked foods. No link between acrylamide levels in food and cancer risk has been established and based on the evidence to date, the UK Food Standards Agency has advised the public not to change their diet or cooking methods. However, the Scientific Committee on Food of the European Union (EU) has endorsed recommendations made by Food and Agriculture Organisation/World Health Organization which include researching the possibility of reducing levels of acrylamide in food by changes in formulation and processing. Cereals have a long history of use by humans. Cereals are staple foods, and are important sources of nutrients in both developed and developing countries. Cereals and cereal products are an important source of energy, carbohydrate, protein and fibre, as well as containing a range of micronutrients such as vitamin E, some of the B vitamins, magnesium and zinc. In the UK, because of the mandatory fortification of some cereal products (e.g. white flour and therefore white bread) and the voluntary fortification of others (e.g. breakfast cereals), cereals also contribute significant amounts of calcium and iron. Cereals and cereal products may also contain a range of bioactive substances and there is growing interest in the potential health benefits these substances may provide. Further research is required in this area, including identification of other substances within cereals and their bioavailability. There is evidence to suggest that regular consumption of cereals, specifically wholegrains, may have a role in the prevention of chronic diseases such as coronary heart disease, diabetes and colorectal cancer. The exact mechanisms by which cereals convey beneficial effects on health are not clear. It is likely that a number of factors may be involved, e.g. their micronutrient content, their fibre content and/or their glycaemic index. As there may be a number of positive health effects associated with eating wholegrain cereals, encouraging their consumption seems a prudent public health approach. To increase consumption of wholegrain foods, it may be useful to have a quantitative recommendation. Additionally, a wider range of wholegrain foods that are quick and easy to prepare would help people increase their consumption of these foods. As cereal products currently contribute a considerable proportion of the sodium intake of the UK population, manufacturers need to continue to reduce the sodium content of foods such as breakfast cereals and breads where possible. Nutrition labelling is currently not mandatory in the UK, although many manufacturers provide information voluntarily. The fibre content of most UK foods is still measured using the Englyst method rather than the American Association of Analytical Chemists (AOAC) method used by other EU countries and the USA. However, UK recommendations for fibre intake currently relate to fibre measured by the Englyst method and not the AOAC method, and hence need revisions. EU changes to labelling regulations will see the labelling of common foods and ingredients causing allergic reactions, including cereals containing gluten and products derived from these foods. The introduction of EU legislation covering health claims may help consumers identify foods with proven health benefits. Several misconceptions exist among the public with regard to cereals and cereal products. Firstly, many more people believe they have a food intolerance or allergy to these foods than evidence would suggest and, secondly, cereals are seen by some as ‘fattening’. The public should not be encouraged to cut out whole food groups unnecessarily and, as cereals and cereal products provide a range of macro‐ and micronutrients and fibre, eliminating these foods without appropriate support and advice from a registered dietitian or other health professional could lead to problems in the long term. In the future it is possible that white flour in the UK may be fortified with folic acid (the synthetic form of the B vitamin folate) to decrease the incidence of neural tube defects during pregnancy. Such a move could also be of benefit for heart health, as poor folate status is associated with high homocysteine levels, an emerging risk factor for cardiovascular disease. However, high intakes of folic acid can mask vitamin B₁₂ deficiency, a condition that occurs more frequently with age and has serious neurological symptoms affecting the peripheral nervous system. Manipulating the expression of native genes can increase the disease resistance of cereal crops. Novel genes may also be used for this purpose, as well as for developing cereals with resistance to herbicides, and cereals with improved nutritional properties (e.g. increased levels of iron in cereals and of beta‐carotene in rice). The long‐term consequences and consumer acceptability of such advances must be considered and consumer choice maintained. There is a continual growth in the knowledge of the interactions between human genes and nutrients, and in the future it may be possible to target specific nutrition messages to people with specific genetic profiles.

     

Nutritional aspects of oilseeds

Summary   Oilseeds, such as soybean, cottonseed, rapeseed (canola), sunflower seed and peanut, are annual plants ( O'Brien et al . 2000 ). They are the largest source of vegetable oils even though most oil-bearing tree fruits provide the highest oil yields ( e.g. olive, coconut and palm trees) ( Gunstone 2002 ). Oilseeds are also used in animal feed because of their high protein content. Their seeds contain energy for the sprouting embryo mainly as oil, compared with cereals, which contains the energy in the form of starch ( Lucas 2000 ). This article reviews the main types of oilseeds; their production and processing into oil. It focuses on the role of oilseeds and their by-products in human health and disease, and highlights new developments that may provide even more benefits for health in the future.     

Effect of wheat flour, Bengal gram flour and corn flour on lipid metabolism in rats

Male albino rats were fed on respective diets of wheat flour, Bengal gram flour and corn flour for 8 weeks at the 59% level. It was observed that the increase in weight after wheat flour and Bengal gram flour feeding was 6.8 and 12.0% respectively and that the decrease after corn flour feeding was 5.2% as compared to the control animals on sucrose diet. Serum cholesterol and liver cholesterol levels were significantly (p less than 0.01) decreased after wheat flour, Bengal gram flour and corn flour feeding.     

Nutritional aspects of infection

Current knowledge is examined about the means whereby ascariasis, hookworm disease, strongyloidiasis and trichuriasis may contribute to the aetiology of human malnutrition. Results from experiments with related parasites in the laboratory have demonstrated the role of gastrointestinal helminthiases in animal malnutrition. Some evidence shows that in children, infection with the intestinal stages of Ascaris lumbricoides is associated with reduced growth rate, disturbed nitrogen balance, malabsorption of vitamin A, abnormal fat digestion, lactose maldigestion and an increased intestinal transit time. The main impact of hookworm infection is its relationship with iron-deficiency anaemia which may have effects at the community level as regards work and productivity in adults and learning and school performance in children. More research is needed to extend knowledge of the nutritional impact of ascariasis and hookworm disease in order to establish their public health significance. Research is needed also to identify the range of nutritional effects on man that occur as a result of trichuriasis and strongyloidiasis. The significance of less prevalent and more localized gastrointestinal helminthiases should not be ignored.     

Nutritional aspects of human lactation

This paper reviews the literature on the incidence and duration of breast-feeding in various countries, the volume and composition of breast milk, the health and nutrition of breast-fed babies as judged by growth and morbidity, maternal nutritional requirements during lactation, and the effect of prolonged lactation on maternal health. It appears that lactation can be as well sustained by impoverished as by affluent mothers, and that even in communities where malnutrition is common the average growth of infants is satisfactory up to the age of about 3 months on a diet of breast milk alone. Breast milk appears to have specific anti-infective properties, but prolonged breast-feeding will not prevent infections among older infants reared in a poor environment. The authors believe that breast-feeding is the best form of nutrition for the young infant and deplore its decline in modern industrial societies. The recommendations of various FAO/WHO Expert Groups on nutritional intakes during lactation are summarized. The need for an increased daily energy intake of 4.2 MJ (1 000 kcal) is questioned, and an increase of 2.5 MJ (600 kcal) is suggested. Data on the effect of prolonged lactation on the health of the mother are scanty; body weight appears to be maintained even among poorly nourished mothers. The authors stress the need for well-planned and technically adequate studies of the material and psychological factors involved in breast feeding.