Chemical,functional, and nutritional properties of sunflower protein products

Sunflower flours and protein concentrates have potential food uses because of their high protein content, white color, bland flavor, and absence of antinutritive factors. Procedures have been developed for removal of chlorogenic acid which forms green and brown colors under alkaline pH, and selection for low chlorogenic acid cultivars is underway in plant breeding programs. Further research is needed on dehulling techniques and possible problems associated with high levels of sugars in sunflower flour. Sunflower flours and concentrates have excellent fat absorption, oil emulsification, and whipping properties. Wieners supplemented with sunflower products showed low shrinkage during the smokehouse treatment and low cooking losses due to high fat and water absorptions. Sunflower-supplemented wieners did score poorly in peelability and organoleptic tests. Sunflower proteins had an excellent amino acid balance except for low lysine content and, in feeding trials with rats, showed high protein efficiency ratios when blended with legume or meat proteins.     

Enzymatic hydrolysis pretreatment for mechanical expelling of soybeans

Mechanical expelling of soybeans with enzymatic hydrolysis as pretreatment was investigated, and the process parameters were optimized by means of response surface methodology. Enzyme pretreatment enhanced both the amount of extractable oil in soybeans and oil extractability. A second-order response surface model was developed to predict the expelled oil as a function of the six process parameters investigated. The optimum was found at: Moisture content during hydrolysis, 23.00% wet basis (w.b.); enzyme concentration, 11.84% vol/wt; incubation period, 13.24 h; moisture content during pressing, 9.36% w.b.; pressing pressure, 75 MPa; and pressing time, 5.36 min. The parameters had no interactive effects on expelled oil. Pressing pressures above 75 MPa caused extrusion. Under the optimal conditions, oil expelled from dehulled cracked soybeans by static pressing at room temperature (18°C) was 63.5% of the total extractable oil. Much higher oil recovery would be expected in actual screw expellers due to dynamic pressing and higher operating temperature. Oil recovery could be further increased by adding one or more conventional pretreatments to the enzymatic hydrolysis pretreatment investigated in this study.     

Enzymatic hydrolysis of extruded-expelled soy flour and resulting functional properties

Limited hydrolysis (4% degree of hydrolysis) of extruded-expelled soy flour protein (protein dispersibility index=21) that was poor in solubility and other functional properties was evaluated at pilot-plant scale (5 kg of flour) with two endopeptidases and one exopeptidase. Some hydrolysates were merely spray-dried whereas others were jet-cooked at 104°C for 19 s before spray-drying. Solubility, emulsification capacity and stability, foaming capacity and stability, apparent viscosity, and sensory attributes were then characterized. The type of protease used and hydrothermal cooking affected functional and sensory properties. Protein solubility modestly increased with hydrolysis and jet cooking, but emulsification capacity decreased on hydrolysis and was not restored with hydrothermal cooking. Emulsion stability improved in the endopeptidase hydrolysates, but not in the exopeptidase hydrolysates. The foaming capacities of the hydrolysates for both types of enzymes were better than for the unhydrolyzed control. Highly stable foams were obtained after hydrolyzing with exopeptidase and hydrothermal cooking. Ten percent protein hydrolysate dispersions showed large losses in consistency coefficient apparent viscosity, which increased significantly with hydrothermal cooking only for the unhydrolyzed control. Difference-from-control sensory evaluation indicated that both jet-cooked and non-jet-cooked enzyme hydrolysates were different from unhydrolyzed controls.     

Specific limited hydrolysis and phosphorylation of food proteins for improvement of functional and nutritional properties

Limited specific hydrolysis of casein byStaphylococcus aureus V8 protease was used to produce 2% and 6.7% hydrolysates (2 and 6.7% of the peptide bonds hydrolyzed), each containing five polypeptides (by gel filtration) ranging in size from ∼ 16,000 to ∼1,000 daltons. The mixtures of polypeptides had substantially increased solubilities at pH 4.0–4.5, near the isoelectric point of casein. In general, the emulsifying activity index was less for the hydrolysates than for casein; the emulsion stability was higher for the 2% hydrolysate than was the emulsion from casein. Phosphorylation of zein markedly increased the water solubility of zein above and below pH 4. When the free amino acids tryptophan and/or lysine were added to zein in the presence of POC1₃, some amino acids were covalently bound to zein, in addition to covalent attachment of phosphate groups. Threonine did not become incorporated into zein by this method. These derivatives were much more soluble than zein above and below pH 4, the minimum solubility point. A derivative containing 0.98 mol P/mol of zein, along with 1.05% tryptophan and 0.24% lysine, had a relative growth effect onTetrahymena thermophili of 49% that of casein, in comparison to 4.5% for unmodified zein. All the modified zeins had improved emulsifying activity indices.     

Soybean products for feeding infants,children and adults under nutritional stress

This review points out the good quality of well-processed soya products. Normal infants, children and adults are able to utilize the protein and other nutrients present in the soya, when fed these products in amounts that will cover their needs. Under nutritional stress, such as in infant malnutrition, soya products such as soya-milk have been shown to help in the children’s recovery. Clinical and biochemical data show that their recovery is similar to that obtained with cow’s milk. Milk- or lactose-intolerant children and adults, who present a public health problem in some developing countries, could benefit from the high nutritive value and low cost of soy milk. Soya products have been shown to decrease cholesterol and other levels of blood lipids. Considering the availability of the several soya products in the market, this possibility has to be further explored. The utilization of soya products in preparing liquid formulas for oral or tube-feeding opens new fields for the treatment of several diseases, insuring at the same time adequate nutrition for the patients. From a practical point of view, in spite of all that is known about soybeans and soybean products, its use as human food, even in countries where it is produced in large quantities, is very low. It seems that local governments are not aware of the importance of soya for the solution to their serious food and nutrition problems. What is known on the subject has to leave the laboratories, research centers and universities and be transferred as food for the mouths of the needy populations. This has to be understood as an urgent duty of national governments. There is no doubt that soya is the cheapest and one of the best-quality foods available to help solve the present hunger problem of the world today.     

Composition,nutritional, and functional properties,and quality criteria of soy protein concentrates and soy protein isolates

The available commercial soy protein concentrates and soy protein isolates afford the food processor concentrated sources of protein with some interesting and varied functional properties. Each class of products is mild to bland in flavor and light in color. The concentrates contain at least 70% protein and the isolates 90%. The nutritional quality of the proteins is fair to good and can be excellent either by supplementation with 1.5% methionine or by appropriate blending with other sources of proteins. The concentrates provide the food manufacturer with products where a high protein content for unit of volume or wt is needed. The isolates are available for uses where the functional properties reside solely in the protein and the nonprotein components may interfere. The adaptability of the proteins to modification by controlled processing conditions has made it possible for the manufacturers to produce a diversity of products that should be of interest to practically all food formulators.     

Enzymatic hydrolysis of oat and soya lecithin: Effects on functional properties

Enzymatic hydrolysis of oat and soy lecithins and its effects on the functional properties of lecithins were investigated. The phospholipase used was most efficient at low enzyme and substrate concentrations. More fatty acids were released from soy lecithin than from oat lecithin. The maximum degree of hydrolysis was 760 μmol free fatty acids per gram soy lecithin and 170 μmol free fatty acids per gram oat lecithin. On the basis of the total carbohydrate and phosphorus contents in the polar fractions of the lecithins, oat lecithin contained more glycolipids and less phospholipids than soy lecithin. With regard to functional properties, the stability of oil-in-water emulsions was enhanced by hydrolyzed soy lecithin and by crude and hydrolyzed oat lecithins, but only hydrolyzed soy lecithin prevented the recrystallization of barley starch. The dissociation enthalpy of amylose-lipid-complex (AML-complex) was significantly higher when hydrolyzed soy lecithin was present. Hydrolyzed oat lecithin slightly affected the dissociation enthalpy of AML-complex. The other lecithins had no effect on recrystallization or dissociation enthalpies in the barley-starch matrix.     

Improvement of nutritional value and functional properties of soybean glycinin by protein engineering

Glycinin is one of the predominant storage proteins of soybean.To improve its functional properties (heat-induced gelationand emulsification) and/or nutritional value, the A_1aB_1b proglycininsubunit was modified on the basis of genetically variable domainssuggested from the comparison of amino acid sequences of glycinin-typeglobulins from various legumes and nonlegumes and the relationshipsbetween the structure and the functional properties of glycinin.Thus, nucleotide sequences corresponding to each of the variabledomains were deleted from the cDN A encoding the A_1aB_1b proglycinin,and a synthetic DNA encoding four continuous methionines wasinserted into the cDNA region corresponding to each of the variabledomains. Expression plasmids carrying the modified cDNAs wereconstructed and expressed in Escherichia coli strain JM105.Some of the modified proteins were accumulated as soluble proteinsin the cells at a high level and self-assembled. They exhibitedfunctional properties superior to those of the native glycininfrom soybean, which establishes the possibility of creatingtheoretically designed novel glycinins with high food qualities.     

Preschool child feeding, health and nutritional status in Gualaceo, Ecuador

Anthropologic, survey, dietary recall and anthropometric techniques were used to study the correlates of nutritional status of preschool children under five years of age in Gualaceo Ecuador. A widespread stunting was found among the children. Nutritional status was worst among infants comprised between 12 and 23 months old but it improved between April and August, thus suggesting seasonality changes of nutritional status. The correlates of nutritional status (expressed as Z score of weight-for-age) were dietary diversity, birth-spacing, fertility, migration, household income, material goods owned, and parental education. A regression model with these variables predicted 63% of the variability in weight-for-age. The prediction of height-for-age was similar, but only predicted 43% of the variability in height-for-age. Correlates of dietary diversity, birth-spacing, fertility, and migration were child age, maternal age and arm circumference, parental education, use of birth control, household food expenditure, material goods owned, and the raising of animals. Parental education was a correlate of dietary diversity, fertility and migration. Parental education was related to change in weight-for-age in the longitudinal subset. Pre-harvest time and a pathway of illness leading to decreased dietary diversity and to decreased nutritional status in April, were suggested as important to preschool child nutritional status. Hot-cold ideology--resulting in food withdrawal during illness and restriction of high-protein and high-calorie foods--appears to be an important mechanism determining preschool child nutritional status. Breast-feeding, sanitary, higienic, birth control, and drinking (alcohol) practices were suggested as areas that could be improved, in order to improve preschool child nutritional status. Communication between parents and western health care providers was also suggested as an area for improvement.     

Maternal beliefs, feeding practices and nutritional status in Afro-Colombian infants

This study describes maternal practices and beliefs on children feeding and their relationship with nutritional status of Afro-Colombian children aged 6 to 18 months. We combined ethnographic and epidemiological data. We collected information using a food frequency questionnaire. Nine focus groups and 5 deep interviews to mothers of children less than 2 years of age were performed. Our data showed a prevalence of wasting of 2.6% (< -2 SD weight-for-length) and prevalence of stunting of 9.8% (< -2 SD height-for-age). These practices are characterized by a universal onset of breastfeeding, that lasted 10 months in average, and an early introduction of complementary food (mean: 3 months). Breastfeeding is a cultural norm. Weaning is related to new pregnancy, to low milk production and to negative effects of breast process on mothers' health. Early complementary feeding and bottle-feeding are highly valued due to their positive effect on nutritional status and adaptation of children to adult-type diets. The introduction of complementary food after 4 months, the quality of the first food introduced and the diversity of complementary food predicted better nutritional status (p < 0.05). We conclude that nutritional illiteracy and mothers' erroneous beliefs result in 50% of the mothers having inadequate feeding practices. We suggest focused interventions on those beliefs limiting good practices.     

Radiation modification of functional properties in PVC/mica electrical insulations

Summary The effects of γ-irradiation on poly(vinyl chloride) blended with fillers (plasticizer, lead stabilizer and mica) are presented. Mechanical and electrical investigations were carried out on samples that received doses of maximum 160 kGy. The results on tensile strength, volume resistivity and loss factor prove that poly(vinyl chloride) may be used as electrical insulator after short γ-exposure. Because mica plays a role of absorbent for hydrochloric acid formed by PVC degradation, favorable properties are obtained for dose up to 120 kGy. The volume resistivity decreases constantly while tan δ remains unchanged for a large frequency range (10²–10⁵ cps). Mica content of 14% induces a decrease in unirradiated PVC of one order of magnitude. After irradiation at 160 kGy volume resistivity increases of about five times relative to 40 kGy irradiated samples. At 150 kGy tensile strength decreases only with 10%, and elongation at break presents a light modification in the selected dose range. The largest differences between the maximum current values obtained for applied doses are presented by PVC with the highest concentration of mica (14%). At 40 kGy, when the degradation becomes relevant, the dipoles are not efficiently trapped by mica and the current does not attend a steady state for a long period (more than half an hour). For higher doses the steady-state current is reached after only 1–3 minutes, due to crosslinking. Some considerations concerning the consequences of high energy exposure of poly(vinyl chloride) on electrical behaviour are presented.     

Effect of barley flour and freeze-thaw cycles on textural nutritional and functional properties of cookies

Studies were carried out on cookies prepared by incorporating barley flour (10%, 20%, 30%, and 40%) into wheat flour. The cookies were evaluated for their physical, chemical, nutritional, textural and sensory characteristics. All the cookie samples showed high fiber, mineral and protein contents when compared to those from 100% wheat flour. Incorporation of barley flour improved the color of the cookies from pale cream to golden brown. The cookies became crispier as indicated by the reduction in the breaking strength value from 4.94 to 3.29 kg. Considering the color, taste, flavor, surface appearance of the cookies, 30% incorporation of barley flour was found to be optimum giving cookies containing 1.7% β-glucan, 36.6 ppm iron, 31.8 ppm calcium, 22.9 ppm zinc while the texture characteristics showed that 30% barley incorporated cookies had breaking strength of 4.021 kg lower than wheat cookies and also indicating that the product was nutritionally rich as compared to the 100% wheat flour cookies. The incorporation of barley flour increased the antioxidant properties and polyphenolic content and hence increased functional properties of the cookies compared to the control. The prepared product was safe microbiologically as well as chemically upto 6 months of storage in different packaging materials under varying temperature conditions. The cookie dough contained 30% barley flour and 100% wheat flour (control) was allowed to under go frozen storage and freeze-thaw cycles (freeze for 12 h and thaw for 4 h). After each freeze-thaw cycle, cookie dough was evaluated for its texture profile and also dough was baked to prepare cookie and assessed for its physical, textural and sensory characteristics. It was found that cookies prepared after freeze-thawing of dough were crisper than the normal ones.     

Improved functional properties of surgical threads by surface modification with polymer composites

Modern suturing materials are developed with a focus on the requirements of surgeons for the optimum mechanical characteristics; interchangeability; compatibility; safety; a lack of allergic, teratogenic, and cancerogenic action in vivo; and a lack of capillary action. Biologically active (BA) thread with a complex action that was prepared by impregnating polyamide or polyester thread-base with a modified composition based on the biopolymer chitosan and including the antibacterial preparation ciprofloxacin and the germanium-containing preparation Astragerm-C was selected for the studies. The goal was to study the effects of the selected modification method and the composition of the modifier on the functional properties of a new surgical suturing material. It was shown that the produced surgical suturing material had improved functional properties that comply with modern requirements.     

型材专用聚氯乙烯树脂的改性应用研究

介绍了应用福建省东南电化股份有限公司主要产品——型材专用PVC树脂生产PVC型材的改性方法以及对型材性能的影响因素。     

Improving the nutritional properties of rapessed

Canadian plant breeders have recently succeeded in producing rapeseed with <1% erucic acid in the oil and with a very low level of glucosinolates in the meal. One suchBrassica napus cultivar, ‘Tower,’ is now licensed. The meal from ‘Tower’ seed has been subjected to extensive chemical and biological testing and has proven to be a markedly superior product as compared with conventional rapeseed meals. This new cultivar is less goitrogenic and more palatable and gives satisfactory productive performance in animals at use levels well in excess of older varieties. The presence of high levels of erucic acid in older varieties made the oils undesirable, particularly because this compound is not well metabolized by cardiac and certain other tissues and results in pathological changes in a number of experimental animals. ‘Tower’ rapeseed oil is less cardiotoxic than high erucic oils and appears to be no more detrimental when used at the 20% level in animal diets than a number of other oils used in human foods.     

Socioeconomic and nutritional localization, quantification and characterization of functional groups in Panama

Even though there has been an increase in the coverage of governmental services and an adequate national food availability, malnutrition continues to exist in Panamanian children. In order to geographically and administratively identify those groups more seriously affected by this problem and orient governmental actions towards them, data from the National Nutrition Survey carried out in 1980 in 14 occupational (functional) groups were classified. Social, economic and cultural characteristics of each functional group were associated with food and nutrition problems. More than half of the malnourished children fall within the functional groups who work in the agricultural/sector. Within them, more than 40% of the malnourished live in homes where two-thirds of their income is derived from work performed outside their own farms. In urban as well as in rural areas low food availability exists at the family level in 25% of the families with inadequate diets studied. The food problem in the rural area is worsened due to limited access to health services and poor environmental conditions. Therefore, the malnutrition problem in Panama is linked to low incomes that prevent acquisition of sufficient foods and other goods and services, as well as to the difficulty of accessibility to public services by an important part of the population.     

Handling,transport and preparation of soybeans

Present techniques of transportation, receiving, drying, storing and preparing of soybeans are discussed and compared with future techniques.     

Enzymatic modification of soy protein concentrates by fungal and bacterial proteases

Solubility, foaming capacity and foam stability of denatured soy protein concentrate obtained from toasted flour were improved by proteolysis with fungal or bacterial proteases. Emulsifying capacity was unchanged, but emulsion stability decreased; bacterial protease highly improved oil absorption. Also, the bacterial protease was able to solubilize more protein and gave products which foamed more than those obtained with the fungal enzyme. However, the stabilizing properties of the bacterial modified soy protein concentrate at the air/water or oil/water interface were inferior. By limited hydrolysis up to degree of hydrolysis 10% most functional properties were improved without greatly reducing emulsion stability and water absorption.     

Enzymatic modification of proteins of commercial sesame meals (Sesamum indicum, L.)

Sesame (Sesamum indicum, L.) is one of the most important oilseed crops in Venezuela. However, the low solubility of the flour made of commercial meals does not allow its use in the preparation of fluid foods. To solve this situation, the alternative of solubilizing the sesame proteins by an enzymatic method, using commercial proteases, was studied. Hydrolysis was carried out with two types of bacterial proteases: neutrasa 0.5L, and alcalase 0.6L. Basically, the process consisted of milling and sieving the sesame cake (60 mesh), concentrating the proteins by solubilizing them at a pH of 9.5, and then precipitating at a pH of 4.5. Proteins were hydrolyzed by an enzymatic method, and the hydrolysates freeze-dried and spray-dried. Optimal conditions of hydrolysis using neutrase 0.5L at a pH of 7 were: 6% substrate concentration, 3% enzyme:substrate ratio, temperature 50 degrees +/- 1 degree C, and hydrolysis degree of 8%. When alcalase 0.6L was used at a pH of 8, optimal conditions were: 8% substrate concentration, 2.3% enzyme:substrate ratio, temperature 58 degrees +/- 1 degree C, and hydrolysis degree of 10%. The enzyme affinity (Km) was best at temperatures near the optimal temperature for the hydrolysates. Dried hydrolysates had protein values which ranged between 66.3% and 66.9% and a nitrogen solubility in water, of approximately 85%. Hydrolysis yields referred to the concentrate dried mass were 42% for the atomized hydrolysate, and 56% for the freeze-dried one. In conclusion, the enzymatic hydrolysis process improved the nitrogen solubility in water of the sesame proteins.