糖蜜味精废水饲料化的生产实践

主要介绍了利用糖蜜味精废水采用干燥法试制速溶蛋白产品的依据及其禽畜饲养效果，并对存在问题进行了讨论。     

Angiotensin I-converting enzyme (ACE) inhibitory activities of sardinelle (Sardinella aurita) by-products protein hydrolysates obtained by treatment with microbial and visceral fish serine proteases

The angiotensin I-converting enzyme (ACE) inhibitory activities of protein hydrolysates prepared from heads and viscera of sardinelle (Sardinella aurita) by treatment with various proteases were investigated. Protein hydrolysates were obtained by treatment with Alcalase^®, chymotrypsin, crude enzyme preparations from Bacillus licheniformis NH1 and Aspergillus clavatus ES1, and crude enzyme extract from sardine (Sardina pilchardus) viscera. All hydrolysates exhibited inhibitory activity towards ACE. The alkaline protease extract from the viscera of sardine produced hydrolysate with the highest ACE inhibitory activity (63.2 ± 1.5% at 2 mg/ml). Further, the degrees of hydrolysis and the inhibitory activities of ACE increased with increasing proteolysis time. The protein hydrolysate generated with alkaline proteases from the viscera of sardine was then fractionated by size exclusion chromatography on a Sephadex G-25 into eight major fractions (P₁–P₈). Biological functions of all fractions were assayed, and P₄ was found to display a high ACE inhibitory activity. The IC₅₀ values for ACE inhibitory activities of sardinelle by-products protein hydrolysates and fraction P₄ were 1.2 ± 0.09 and 0.81 ± 0.013 mg/ml, respectively. Further, P₄ showed resistance to in vitro digestion by gastrointestinal proteases. The amino acid analysis by GC/MS showed that P₄ was rich in phenylalanine, arginine, glycine, leucine, methionine, histidine and tyrosine. The added-value of sardinelle by-products may be improved by enzymatic treatment with visceral serine proteases from sardine.     

Application of protein-based edible coatings for fat uptake reduction in deep-fat fried foods with an emphasis on muscle food proteins

BackgroundDeep-fat frying is a common cooking method where fat or oil is used as the heat transfer medium, in direct contact with the food at a temperature above the boiling point of water. During the deep fat frying method, oil not only serves as a heating medium but also absorbs into food, increasing the total fat content. As a result, consumption of deep-fat fried foods has been associated with coronary heart diseases, obesity and type 2 diabetes. Selection of an appropriate food coating before frying may act as a barrier to moisture loss, which is important commercially, and also reduce fat uptake during frying.Scope and approachThis paper succinctly reviews different protein sources for edible coatings and compare them with muscle food proteins which were used in deep-fat fried foods.Key findings and conclusionsProtein-based coatings have been explored as potential coating materials in fat-uptake reduction. Comparatively, proteins are able to form films with better mechanical and barrier properties than polysaccharides. Application of muscle food proteins (myofibrillar proteins) as coatings, which are rich in these proteins, is novel and could be product-friendly for deep-fried muscle foods.     

Reactions of chlorogenic acid and quercetin with a soy protein isolate--influence on the in vivo food protein quality in rats

Plant phenolic compounds are known to interact with proteins producing changes in the food (e. g., biological value (BV), color, taste). Therefore, the in vivo relevance, especially, of covalent phenol-protein reactions on protein quality was studied in a rat bioassay. The rats were fed protein derivatives at a 10% protein level. Soy proteins were derivatized with chlorogenic acid and quercetin (derivatization levels: 0.056 and 0.28 mmol phenolic compound/gram protein). Analysis of nitrogen in diets, urine, and fecal samples as well as the distribution of amino acids were determined. Depending on the degree of derivatization, the rats fed with soy-protein derivatives showed an increased excretion of fecal and urinary nitrogen. As a result, true nitrogen digestibility, BV, and net protein utilization were adversely affected. Protein digestibility corrected amino acid score was decreased for lysine, tryptophan, and sulfur containing amino acids.     

Gamma irradiation of cowpea (Vigna unguiculata L. Walp) flours and pastes: Effects on functional,thermal and molecular properties of isolated proteins

In a previous study irradiation of cowpea flours and pastes at medium (10 kGy) and high (50 kGy) doses resulted in significant changes in protein-related functional properties. To understand some of the effects of gamma irradiation on cowpea proteins in particular, we isolated proteins from cowpea flours (FPC) and pastes (PPC) treated with gamma irradiation at 2, 10, and 50 kGy and analyzed their functional, thermal and molecular properties. Nitrogen solubility index of both FPC and PPC decreased, whereas oil absorption and emulsion capacities increased significantly with increasing irradiation dose. Differential scanning calorimetry showed decreases in transition temperatures (T_d) and enthalpies (ΔH), indicating a progressive denaturation of cowpea proteins with increasing irradiation. Size exclusion HPLC revealed increases in protein molecular weights, probably due to protein–protein cross-linking with irradiation in a dose-dependent manner. Reducing SDS-PAGE of FPC and PPC samples seems to suggest that the contribution of disulphide bonds to irradiation-induced cowpea protein–protein cross-linking is small.     

Fractionation and characterization of tartary buckwheat flour proteins

Protein fractions (albumin, globulin, prolamin and glutelin) were extracted from defatted tartary buckwheat flour. Albumin was the predominant protein fraction (43.8%) followed by glutelin (14.6%), prolamin (10.5%), and globulin (7.82%). Albumin was relatively rich in histidine, threonine, valine, phenylalanine, isoleucine, leucine and lysine. Globulin had high levels of methionine and lysine. Prolamin was high in histidine, threonine, valine, isoleucine, and leucine. Glutelin was rich in histidine, threonine, valine, isoleucine, and leucine. SDS–PAGE analysis, under non-reductive and reductive conditions, showed that disulfide bonds existed in the four fractions. Non-reduced albumin showed major bands at 64, 57, 41, and 38 kDa, and globulin at 57, 28, 23, 19 and 15 kDa. Reduced albumin and globulin shared two common bands at 41 and 38 kDa. Reduced prolamin showed major bands at 29, 26, 17 and 15 kDa. In vitro pepsin digestibility of the four fractions (from high to low) was: albumin > globulin > prolamin and glutelin.     

Effect of the stage of growth,wilting and inoculation in field pea (Pisum sativum L.) silages. II. Nitrogen fractions and amino acid compositions of herbage and silage

The aim of the study was to investigate the effects of stage of maturity, wilting and inoculant application on proteolysis in field pea herbage and silage in northern Italy. Semi‐leafless field peas were harvested at four progressive morphological stages (end of flowering, I; beginning of pod filling, II; advanced pod filling, III; beginning of ripening, IV). For each stage of growth, the herbage was field wilted to a dry matter (DM) content around 330 g kg^?1. The unwilted and wilted herbages were ensiled with (I) and without (C) a lactic acid bacteria (LAB) inoculant. The stage of growth significantly affected all the nitrogen fraction concentrations both in herbage and in silage. Extensive proteolysis took place in silages made at early morphological stages and characterised by a high crude protein content (around 240 g kg^?1 DM), as shown by the non‐protein nitrogen (NPN) value (around 700 g kg^?1 total N or higher). Neither inoculum nor wilting helped to reduce the protein degradation in these silages. The level of proteolysis was reduced in silages made from the pod filling stage onwards where most of the protein was localised in the seed and a better fermentation pattern was observed. The amino acid (AA) composition of silages made at stage IV was close to that of fresh herbage, with minimal losses of nutritionally essential amino acids for ruminants. Copyright © 2006 Society of Chemical Industry     

Applicability of NIR spectroscopy to determine oil and other physicochemical parameters in Rosa mosqueta and Chilean hazelnut

Due to the increasing interest in certain components, specially the oil, from non-conventional seeds as Rosa mosqueta (Rosa rubiginosa) and Chilean hazelnut (Gevuina avellana), quick determinations of oil and other parameters were carried out by using near-infrared (NIR) spectroscopy. Moisture, oil, fiber (as acid detergent fiber) and protein from solid samples of the seeds as mentioned, along with those of soybean (Glycine max), already analyzed by NIR and for serving as control for the variability of the method, were studied. Sample interactions to NIR radiations were processed using the multivariate regression algorithm Partial Least Squared (PLS) to build a calibration model. Standard error of cross-validation (SECV) was used to estimate the prediction error. Moisture of Rosa mosqueta, Chilean hazelnut presscake and soybean meal (in the ranges 10–15, 10–15, 8–10%, respectively), acid detergent fiber (60–68, 12–16, 10–15%, respectively), oil (1–4, 14–20, 5–13%, respectively) and protein (1–5, 8–15, 27–45%, respectively) were previously determined by wet analysis using standard methods, so creating a library. The possibility to analyze parameters from very different oilseeds with an acceptable uncertainty was also established. Standard errors of cross-validation were between 1.25 and 2.99%, being the oil content the best predicted parameter.     

Impact of a thermal treatment on the emulsifying properties of egg yolk. Part 1: Effect of the heating time

The denaturation degree of egg yolk (EY) protein was determined in dilute EY suspensions containing 20% fresh EY (w/w) as a function of the heating time (0–40 min.) at 74 °C. The impact of such a thermal treatment on the emulsifying properties of the EY was studied in a fluid oil-in-water (O/W) emulsion containing 30% oil (v/v). Heating of the EY prior to emulsification appeared to slightly increase the oil droplet size and to drastically decrease of the level of flocculation. It was also shown that the concentration of proteins in the interfacial film increases with increasing degree of EY protein denaturation, which is thought to be responsible for the change in the colloidal interactions between droplets. The increased steric repulsions due to the increased interfacial protein concentration could explain the decrease of oil droplet flocculation. The impact of such modifications on the rheological properties and creaming stability of the emulsions is discussed.     

综合利用河虾加工下脚料的工艺研究

本文测定了河虾加工下脚料的成分,研究了蛋白酶对河虾加工下脚料作用的最适条件,分析了采用酶法回收的蛋白质提取物的组成及性质,提出了采用酶法和化学法相结合的综合利用河虾加工下脚料的工艺路线。