Functional and nutritional properties of acylated rapeseed proteins

Rapeseed flour was acylated to various degrees with acetic and succinic anhydrides to produce acetylated rapeseed protein concentrates (SRPC) and succinylated rapeseed protein concentrates (SRPC), respectively. With both acylating agents, approximately 5–82% (ARPC-5 to ARPC-82) and 5–56% (SRPC-5 to SRPC-56) of ε-amino groups of lysine were acylated. Changes in functional properties were monitored; nitrogen solubility, emulsifying properties and specific viscosity were improved by acylation. The effects on functional properties were more pronounced with succinylation than acetylation. The nutritive value of succinylated rapeseed protein concentrates was determined and compared with those of unmodified rapessed protein concentrate and rapessed flour. Succinylation reduced the availability of lysine and decreased (p<0.05) the net protein ratio (NPR) and apparent digestibility coefficient (ADC) of nitrogen in rapessed protein concentrates. Supplementation of SRPC with lysine improved the NPR compared to that of SRPC-56.     

Effects of limited proteolysis on functional properties of ovalbumin

We examined the limited proteolysis of ovalbumin by pepsin and its effect on the functional properties of the ovalbumin. Pepsin hydrolyzed only the single peptide bond of ovalbumin between His-22 and Ala-23. This provided a large intermediate (MW 42,500), P-ovalbumin. A P-ovalbumin solution gave a transparent gel when heated. Under the same conditions, an ovalbumin solution gave a turbid gel. We studied the physicochemical properties of P-ovalbumin and the formation of the transparent gel.     

Hydrolyzed and autolyzed vegetable proteins as functional food ingredients

Hydrolyzed vegetable or plant protein (H.V.P. or H.P.P.) can be defined as mixtures containing amino acids and frequently other substances such as salt and peptides, obtained by hydrolysis of vegetable proteins. On an industrial scale two types of hydrolytic processes are applied: acid and enzymic hydrolysis. HVP estimated sales in the western world are at least $100 million. Most HVPs are produced for internal use by soup manufacturers, for use as vital meaty or savory flavoring ingredients in bouillons, soups, sauces, processed meat, fish and poultry products and snacks. Other HVPs are more ready-made products, or have obtained additional meat flavor value by careful blending and/or by processes based on Maillard-type reactions. Of substantially less importance is the use of HVP as whipping, foaming or areating agent, as nutritional ingredients or as bread or baking improver. Most of the HVPs used for these purposes are only partially hydrolyzed by enzymes or by alkaline treatment. The legal status of HVP, food ingredient or food additive, and its safety was discussed recently at various locations. So far these discussions have resulted in the tentative conclusions that HVPs are food ingredients which need standardization, and which, at their presently used levels, can be considered as being GRAS.     

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.     

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 modification of the functional, nutritional and sensorial properties of soybeans for special feeding

Production of new protein-based products for special nutrition such as hypoallergenic infant formulas, fortified beverages and nutraceutics, require ideal ingredients. Protein ingredients were developed by enzymatic hydrolysis and methionine synthesis of soy protein. Hydrolysis was done at 4% (w/v) using porcine pancreatic enzymes (4% w/w), 50 degrees C, 6 h and pH 8. After drying powder was resuspended (20% w/v) and incubated with 7.6% (w/w) methionine methyl-ester, 1% (w/w) chymotrypsin and 3 M glycerol, 37 degrees C, 3 h and pH 7. Hydrolysates were fractionated by ultrafiltration (UF) before and after enrichment (E): FI > 10, 10 > FII > 3 and 3 > FIII > 1 kDa. Functional properties, amino acid content, anti-physiological factor activities and antigenicity were assayed for all the UF fractions and the soybean meal. Protein quality bioassay and sensorial test of an non-enriched fraction and an enriched fraction were performed. Functional properties were positively modified by hydrolysis and synthesis by using a minimum time and methionine added for the last reaction. After UF all the fractions under 10 kDa showed 100% solubility (pH 4 and 7), good clarity, acceptable foam capacity and negligible antigenicity and antiphysiological activities. Additionally, methionine enrichment enhanced their nutritional value, upgrading sulfur amino acid requirements for infants and adults. Because functionality and nutritional value FIII-E could be used for hypoallergenic infant formulas, FII-E for fortified soluble formulas and nutraceutics and FI-E for a semi-solid baby food.     

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.     

Comparison and synergistic effects of intact proteins and their hydrolysates on the functional properties and antioxidant activities in a simultaneous process of enzymatic hydrolysis

Soy protein isolate (SPI), bovine whey protein (BWP) and egg white protein (EWP) were hydrolyzed with the Flavourzyme 500L^® protease, and the interactions of these substrates and their mixtures on their functional properties and antioxidant activities were studied using a simplex centroid mixture design. Synergistic effects between the formulations containing binary or ternary mixtures were observed for several parameters, especially the DPPH radical-scavenging activity and emulsion activity index, which exhibited increases of up to 45.0 and 1200.0%, respectively, after enzymatic hydrolysis compared to the isolated substrates. The results suggest that the application of the statistical mixture designs in a simultaneous process of enzymatic hydrolysis using different protein sources is an attractive method for improving enzyme performance and identifying optimum formulations.     

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.     

Functional and nutritional properties of modified proteins of sesame (Sesamum indicum, L.)

A study on the functional and nutritional properties of sesame (Sesamum indicum, L.) flour, concentrate and enzymatic hydrolysates, demonstrated that nitrogen solubility of the hydrolysates is improved, in water (85%) and at different pHs (91-95%), by the action of neutrasa 0.5L and alcalasa 0.6L, yielding a product with good emulsifying and improved foaming properties. Hydrolysates produced by the pH-stat method, then freeze-dried and spray-dried presented a PER of 1.1 and 0.9, respectively. The flour and the concentrate had PER values of 1.2. Supplementation of one of the hydrolysates with soya hydrolysate (1:1), improved the PER to a value similar to that of casein. Use of neutrasa 0.5L and alcalasa 0.6L enzymes, enhances the sesame protein solubility without modifying extensively the PER. Besides, it yields a dehydrated product with improved emulsifying and foaming properties.     

Enzyme-modified proteins from corn gluten meal: Preparation and functional properties

Functional properties of proteins in corn gluten meal (CGM) can be improved by enzyme hydrolysis combined with membrane technology. CGM was treated with a protease (Alcalase), resulting in 30–50% of the proteins being converted to soluble peptides. Conversions were higher when CGM was pretreated with cysteine or sulfite. Solubility and clarity of the enzyme-modified proteins were better at higher degrees of hydrolysis (DH). Higher DH increased initial foam volume but decreased foam stability. Membrane filtration of the hydrolyzed CGM reaction mixture resulted in two peptide fractions, as determined by size-exclusion high-performance liquid chromatography. Protein solubility of the membrane-permeable fraction was 90–99% compared with 8% for unmodified proteins. Larger-pore membranes improved foaming but decreased solubility and clarity. Moisture sorption at a water activity of 0.97 was 3.75 g water per gram of enzyme-modified/ultrafiltered CGM, compared with 0.2 g/g for the unmodified CGM.     

Functional properties of oat proteins modified by acylation,trypsin hydrolysis or linoleate treatment

Proteins extracted from defatted oats were chemically modified by acylation (succinylation and acetylation), potassium linoleate treatment or partial hydrolysis with trypsin. Total essential amino acid content was slightly lowered by acetylation, but unaffected by succinylation. Gel filtration chromatography showed some dissociation of oat polypeptides by succinylation, while trypsin hydrolysis caused considerable breakdown of the protein. Solubility and emulsifying properties were significantly improved by all the modifications. Fat binding capacity was improved by acylation and linoleate treatment, while water hydration capacity and foaming properties were improved by trypsin and linoleate modifications. The gelling property was improved by acylation. When meat protein was substituted with oat protein in model wieners, there was a decrease in cook yield, cohesiveness and firmness. However, when compared to the unmodified oat protein, succinylation led to an improvement in performance in an emulsified meat system.     

Gauging food and nutritional care quality in hospitals

ABSTRACT: BACKGROUND: Food and nutritional care quality must be assessed and scored, so as to improve health institution efficacy. This study aimed to detect and compare actions related to food and nutritional care quality in public and private hospitals. METHODS: Investigation of the Hospital Food and Nutrition Service (HFNS) of 37 hospitals by means of structured interviews assessing two quality control corpora, namely nutritional care quality (NCQ) and hospital food service quality (FSQ). HFNS was also evaluated with respect to human resources per hospital bed and per produced meal. RESULTS: Comparison between public and private institutions revealed that there was a statistically significant difference between the number of hospital beds per HFNS staff member (p = 0.02) and per dietitian (p < 0.01). The mean compliance with NCQ criteria in public and private institutions was 51.8% and 41.6%, respectively. The percentage of public and private health institutions in conformity with FSQ criteria was 42.4% and 49.1%, respectively. Most of the actions comprising each corpus, NCQ and FSQ, varied considerably between the two types of institution. NCQ was positively influenced by hospital type (general) and presence of a clinical dietitian. FSQ was affected by institution size: large and medium-sized hospitals were significantly better than small ones. CONCLUSIONS: Food and nutritional care in hospital is still incipient, and actions concerning both nutritional care and food service take place on an irregular basis. It is clear that the design of food and nutritional care in hospital indicators is mandatory, and that guidelines for the development of actions as well as qualification and assessment of nutritional care are urgent.     

The functional requirements of proteins for foods

As a growing amount of research attention has been diverted, for a number of reasons, from the traditional protein foods to the so-called unconventional food proteins, an awareness has increased of the need to understand the functional properties of these proteins. Some empirical functionality tests have been devised, but it is submitted that many of these could yield misleading information, inasmuch as they often ignore or even run counter to the environmental interactions to which proteins are exposed in food systems. Some examples are given of the influence of the ionic environment upon one basic functional property of proteins, their solubility in aqueous solution. One of 21 papers presented at the Symposium, “Oilseed Processors Challenged by World Protein Need,” ISF-AOCS World Congress, Chicago, September 1970.     

纤维素降解辅助蛋白及其作用机理研究进展

化石燃料的日渐枯竭及环境污染的日益严重使得生物质原料的资源化、能源化利用受到广泛关注。木质纤维素是地球上最丰富的可再生生物质,其通过生物转化可获得多种燃料和化学品,而纤维素难以有效糖化是木质纤维素生物转化的主要瓶颈。本文介绍了某些纤维素非降解性辅助蛋白提高纤维素酶解效率的相关研究进展,重点分析了近些年发现并研究较多的裂解性多糖单加氧酶（AA9和CBM33）、纤维二糖脱氢酶（CDH）、扩展蛋白（expansin）、膨胀素（SWOI）等几种纤维素辅助蛋白及其协助纤维素降解的机理,总结出这些辅助蛋白主要是通过促进木质素或半纤维素降解以及破坏纤维素的氢键网络和结构来协同纤维素酶催化纤维素的糖化降解。通过以上概括和评述,认为这些辅助蛋白虽然一定程度上可以促进纤维素的酶解,但其研究和应用还仅限于实验室基础研究,如何将其有效并廉价应用于木质纤维素生物转化的工业过程还面临着巨大挑战。指出相关研究工作的重点还需要从廉价而有效的蛋白筛选与构建、协同作用机理解析、过程优化与强化等方面深入开展。     

Effects of cooking and screw-pressing on functional properties of Cuphea PSR23 seed proteins

This investigation determined the effects of oil processing conditions on some functional properties of Cuphea PSR23 seed proteins to evaluate their potential for value-added uses. Flaked Cuphea seeds were cooked at 82°C (180°F) for 30, 75, or 120 min in the seed conditioner and then screw-pressed to extract the oil. Cooked flakes and press cakes were analyzed for proximate composition and protein functional properties. Results were compared with those of unprocessed ground, defatted Cuphea seeds. Protein from unprocessed Cuphea seeds had excellent emulsifying properties, poor foaming properties, poor solubility (10%) at pH 4–7, and much greater solubility at pH 2 and 10 (57 and 88%, respectively). Solubility profiles showed that cooking the flaked seeds to 82°C for 30 min resulted in a 50–60% reduction in soluble proteins. Cooking for 120 min gave <6% soluble proteins at all pH levels. Cooking for 75 min gave good oil yields but also resulted in <10% soluble proteins at pH 2–7 and 25% soluble proteins at pH 10. Seed cooking and screw pressing during oil extraction had significant detrimental effects on the solubility of Cuphea seed protein but generally improved its foaming capacity and emulsifying activity.     

The hydrolysis of proteins by microwave energy

Microwave energy, at manually-adjusted, partial power settings has been used to hydrolyse bovine serum albumin at 125 °C. Hydrolysis was complete within 2 h, except for valine and isoleucine which were completely liberated within 4 h. The aminoacid destruction was less than that observed at similar hydrolysis conditions with other methods and complete hydrolysis was achieved more rapidly. These results provide a basis for automating the process of amino-acid hydrolysis.