复配型大豆浓缩蛋白功能特性的应用研究

主要介绍了一种复配型大豆浓缩蛋白在注射类肉制品中的应用。研究表明复配得到的浓缩蛋白应用于肉制品中时,不仅提高了肉制品的出品率,改善了肉制品的质构和口感,而且能够降低肉制品生产成本。感官评分显示,用注射复配型浓缩蛋白制作的肉制品在外观、风味、口感和总接受性等各项指标的评分均达到或高于添加注射型分离蛋白制作的产品。     

Physicochemical properties of soya bean protein gel prepared by microbial transglutaminase in the presence of okara

The influences of okara on the gelling and secondary protein structure of soya protein isolate (SPI) were investigated. Okara was ultra‐refined by high‐pressure homogenisation. The resulting particle sizes and microscopic morphologies were determined using a laser particle size analyser and a confocal laser scanning microscope, respectively. After okara homogenisation, surface area average particle size (D₃₂) decreased from 49.68 to 23.29 μm and volume average particle size (D₄₃) decreased from 118.94 to 55.08 μm. Dynamic rheological measurements showed that the storage (G′) and loss (G′′) moduli of SPI gelled in the presence of okara were mostly higher than those of SPI gels alone and were increased as the okara amounts increased. Linear law analysis revealed that SPI–okara gels were weak gels and frequency independent. Fourier transform infrared spectroscopy showed that okara and transglutaminase influenced the prevalence of α‐helices, β‐turns, β‐sheet and random coils.     

Blockage of available lysine at different stages of infant cereal production

Determination of available lysine was used to assess the heat damage produced during the processing of cereals for infant foods. The infant cereals analysed were: wheat, 7 and 8 cereals, rice, rice–corn, rice–corn–soy and oat. Lysine losses during the toasting of flours ranged between 14 and 29%. Roller‐drying treatment caused considerable heat damage, with a 53% decrease of available lysine in roller‐dried rice–corn–soy. However, oat flour was less susceptible, with a 5% reduction in available lysine during roller‐drying. © 1999 Society of Chemical Industry     

大豆胨制备工艺条件研究

以脱脂豆粕为原料,通过"碱提酸沉"法制备大豆分离蛋白,经正交实验确定的最适条件是碱液萃取温度为50℃、碱液萃取p H值为8、酸沉淀p H值为4.0。以所得的大豆分离蛋白为反应底物制备大豆胨并优化其制备工艺。结果表明,反应的最佳条件为:酶解温度为55℃,酶解p H值为7.5,底物浓度为5%,E/S为16 g/kg。将按照此工艺条件制备出的大豆胨的各项理化指标与所购标准品相比,差异不大。氨基酸分析结果表明,大豆胨中必需氨基酸种类丰富齐全,可为微生物的生长提供丰富的营养。     

Effects of jugular-infused lysine, methionine, and branched-chain amino acids on milk protein synthesis in high-producing dairy cows

In addition to lysine and methionine, current ration-balancing programs suggest that branched-chain amino acid (BCAA) supply may also be limiting in dairy cows. The objective of this study was to investigate whether BCAA, leucine, isoleucine, and valine become limiting for milk protein synthesis when methionine and lysine supply were not limiting. Nine multiparous Holstein cows with an average milk production of 53.5 ± 7.1 kg/d were randomly assigned to 7-d continuous jugular infusions of saline (CTL), methionine and lysine (ML; 12 g and 21 g/d, respectively), or ML plus leucine, isoleucine, and valine (ML+BCAA; 35 g, 15 g, and 15 g/d, respectively) in a 3 × 3 Latin square design with 3 infusion periods separated by 7-d noninfusion periods. The basal diet consisted of 40% corn silage, 14% alfalfa hay, and a concentrate mix, and respectively supplied lysine, methionine, isoleucine, leucine, and valine as 6.1, 1.8, 4.7, 8.9, and 5.3% of metabolizable protein. Dry matter intake (23.9 kg/d), milk yield (52.8 kg/d), fat content (2.55%), fat yield (1.33 kg/d), lactose content (4.77%), lactose yield (2.51 kg/d), and milk protein efficiency (0.38) were similar across treatments. Protein yield and protein content were not significantly different between ML (1.52 kg/d and 2.88%, respectively) and ML+BCAA (1.51 kg/d and 2.83%, respectively), but they were significantly greater than that of CTL (1.39 kg/d and 2.71%). Cows that received ML+BCAA had less milk urea nitrogen content (10.9 mg/dL) compared with milk of CTL cows (12.4 mg/dL) and ML cows (11.8 mg/dL). Whereas high-producing cows responded positively to methionine and lysine supplementation, no apparent benefits of BCAA supplementation in milk protein synthesis were found. Infusion of BCAA may have stimulated synthesis of other body proteins, probably muscle proteins, as evidenced by decreased milk urea nitrogen.     

Nutritional characterization of high protein and high lysine barley lines

Six high protein and high lysine barley lines were derived from four crosses involving high protein andlor high lysine donors, ie Riso 1508 and SV 73608 (Hiproly×Mona⁵), with well adapted local strains V 5681 and V 4342. The trial was grown at the Wheat Research Institute, Faisalabad, Pakistan. The lines were chemically and nutritionally characterized and the results were compared with the parents. The biological value, net protein utilization and lysine contents were higher in all the derived lines than in their local parents, ie V 5681 and V 4342. The increased lysine levels in the lines B 82503 and B 82507 may be a consequence of the reduction of prolamin fractions with simultaneous increases in salt soluble fractions. In all the lines, lysine and nutritional quality increase were a reflection of high protein andlor high lysine parents. The line B 82503 had grain yield comparable to its local parent V 5681 but it was superior in lysine and some nutritional attributes to its high lysine donor parent Riso 1508. In some lines, lysine improvement was achieued without impairing grain yield.     

Effect of hydrochloric acid treatment of palm kernel for dehulling on the nutritional quality of kernel protein

The effect of hydrochloric acid treatment for the dehulling of palm kernel on the nutritional quality of its protein was studied and compared with that of untreated kernel protein and casein. Rats fed a treated defatted kernel protein diet had slightly lower gains in body weight (59·5 g) when compared to those fed a casein diet (64·2 g), while the gains in body weight in the animals fed untreated kernel protein diet were considerably lower (42·5 g). The PER of the treated protein was 2·27 (95% of that of casein) while that of the untreated protein was lower; only 1·63. In the case of the treated protein diet, 80% of food nitrogen was absorbed compared to 94% for casein and 65% for untreated protein, indicating improvement in protein digestibility with HCl treatment. The essential amino acid content of the treated kernel protein was comparable to egg protein. Available lysine content was higher in the treated sample than that of the untreated sample. © 1998 SCI.     

Meta-analysis of milk protein yield responses to lysine and methionine supplementation

Previous reports on milk protein responses to AA supplementation focused on Lys and Met concentrations expressed as a percentage of metabolizable protein, not the amounts of AA supplied. The objective of this study was to quantify the milk protein yield (MPY; g/d) response in studies in which Met or Lys was supplied either by postruminal infusion or in a rumen-protected form. A meta-analysis using a logistic regression model fitted using nonlinear mixed model procedures was performed on results from 23 published studies involving postruminal supplementation of Lys (18 experiments) and Met (35 experiments) in lactating dairy cows. Variance caused by study effect was removed by designation of individual study as subject within the random component within the nonlinear model. Milk protein responses to supplemental Met decreased from 16 to 4 g of milk protein per gram of metabolizable Met intake as Met intake varied from 25 to 70 g per cow per day. Similarly, milk protein responses to supplemental Lys decreased from 5.0 to 3.2 g of milk protein per gram of metabolizable Lys intake as Lys intake varied from 80 to 203 g per cow per day. Assuming Met and Lys concentrations of 2.76 and 7.63 g/100 g of milk protein, respectively, the implied marginal efficiencies of metabolizable AA use for MPY decreased from 44 to 12% for Met and from 39 to 25% for Lys over the range of metabolizable AA intakes. Although the estimated efficiencies were low compared with previous estimates, a low marginal efficiency of amino acid utilization would be expected when amino acid supply is at or near to the animal's requirement, as was the case in these experiments. This suggests that current models that assume both a constant MPY response and constant AA utilization efficiency are inadequate. Models that assume a constant efficiency of AA use will overestimate production responses to individual AA supply, especially when high amounts of metabolizable AA are fed.     

Formation of lysinoalanine following alkaline processing of soya bean meal in relation to the degradability of protein in the rumen

Effects of sodium hydroxide (NaOH) treatment on the formation of lysinoalanine (LAL) and on in-situ and in-vivo utilisation of soya bean meal (SBM) protein were investigated. Defatted SBM was sprayed with 0 (water), 25, 50 and 100 g NaOH (kg^?1 dry matter), dried at 80°C for 2 h and then fed to four rumen cannulated goats in a 4 × 4 Latin square as a mixed diet (9: 1 w/w) of sudangrass hay and the SBM. LAL was not detected in non-alkaline SBM, but the cross-linked amino acid increased according to the level of NaOH addition. The maximum concentration of LAL was 1.26 g per 16 g nitrogen when the highest level of NaOH was applied. The NaOH treatment did not alter the digestibility or the retention of nitrogen of the mixed diet. Addition of NaOH at 25 and 50 g (kg^?1 dry matter) lowered the solubility of protein, while the highest level of treatment had little effect. Lag time and rate of degradation of protein decreased due to the increasing level in NaOH treatment. A significant correlation (r = —0.860, P < 0.01) between LAL content and rate of protein degradation suggested that the formation of cross-linked amino acid would render protein more resistant to microbial degradation in the rumen.     

染料结合法测定稻谷中有效赖氨酸含量

用实验室常见的仪器设备—722型电光分光光度计,对染料结合法(DBL法)测定稻谷中有效赖氨酸含量的最适条件进行了摸索。同时将DBL法与氨基酸自动分析仪测定结果进行了比较,二者相关密切。并用DBL法对我国部分地区主要稻谷品种中有效赖氨酸的含量进行了测定。实验证明,DBL法是测定稻谷中有效赖氨酸的最佳方法,它具有快速、简便、经济、无需特殊仪器且能获得满意结果等优点,适合当前我国的技术水平。     

The rapid determination of chemically reactive lysine in the presence of carbohydrates by a modified trinitrobenzenesulphonic acid procedure

The trinitrobenzene sulphonic acid (TNBS) method has been shown by previous workers to give low results for chemically reactive lysine if carbohydrates are present in the sample. The major factor responsible has now been identified as loss of ?-trinitrophenyl (?-TNP) lysine during the hydrolysis stage, while adsorption of ?-TNP lysine by humins formed from carbohydrates during hydrolysis has been shown to be insignificant. The loss can be minimised by a reduction of the hydrolysis time without affecting the necessary degree of protein hydrolysis. A modified procedure is suggested which is shown to give very similar results to Carpenter's method (incorporating the Booth modification) for pure proteins and to the Silcock method in the presence of carbohydrates. ?-TNP lysine hydrolysed for 90 min or D,L-lysine taken through the trinitrophenylation procedure followed by hydrolysis for 120 min are the most suitable standards. The procedure can be completed in under 6 h and does not require the use of expensive equipment or hazardous chemicals.     

Structural and physicochemical properties of soya bean protein isolate/maltodextrin mixture and glycosylation conjugates

The effect of mixture and conjugation with maltodextrin (MD) in aqueous solution on the structural and physicochemical properties of soya bean protein isolate (SPI) was investigated. Although the mixing of MD would not change the distribution of secondary structure and tertiary conformation of SPI, the protein aggregation was promoted through hydrophobic interaction, which resulted in the decrease in solubility and the improvement of gel strength and water holding capacity (WHC) of SPI/MD mixture. However, glycosylation decreased α-helix and increased β-structure. The bathochromic shift of the fluorescence emission maximum wavelength for SPI/MD conjugates was promoted, resulting in less compact tertiary conformation. These structural modifications might be the reason for the changes in the physicochemical properties of conjugates. After glycosylation, the surface hydrophobicity and solubility were increased, the average particle size was decreased, and the gelation properties were weakened including gel strength and WHC.     

Effect of thermal processing on available lysine,thiamine and riboflavin content in soymilk

Soymilk was heated over a range of temperatures (90–140°C) and times (0–6 h). The available lysine, thiamine and riboflavin content of the soymilk samples were determined. There was no significant change in available lysine during a 3 h heating period at 95°C. At elevated temperatures of 120 and 140°C, optimum heat processed soymilk gave higher measured values of available lysine than did soymilk processed at 95°C. Prolonged heating at 120 and 140°C caused a decline in available lysine. Kinetic data on the thermal degradation of thiamine and riboflavin in soymilk were fitted with first-order kinetics and the kinetic parameters were determined. © 1998 SCI.     

The zinc(II) binding sites of soya bean glycinin

Binding of zinc by glycinin was determined in 0.5 M KCl at pH 6.2. The number of binding sites in the native protein was 51 for 8.5 μM glycinin. Protein modification studies identified the histidine residues as one of the binding sites, and comparison with published data on the histidine content of glycinin suggests that the majority of these residues are on the surface of the protein. Denaturation by 6 M urea increased the number of binding sites to 330. The number of zinc binding sites was found to vary with the protein concentration in 0.5 M KCl. The affinity of zinc for the protein varied with the protein concentration. Increasing the KCl concentration to 1.0 M decreased the affinity of zinc for the protein and increased the number of binding sites. Zinc preferentially binds to EDTA rather than to glycinin. Binding at pH 5.5 resulted in a reduction in the number of binding sites to 23. Ultracentrifugal analysis of glycinin in the presence and absence of zinc gave S_{20, W} values of 13.1 and 11.1, respectively. Calcium and magnesium did not bind to glycinin in 0.5 M KCl at pH 6.2.     

Effects of cooked or roasted full-fat soya bean and soya bean meal on performance and carcass characteristics of growing-finishing pigs

Abstract : Three maize-based diets were formulated to contain 25% each of cooked, or locally roasted full-fat soya bean, or 20% soya bean meal. The diets were fed to 24 Large White, Landrace, Hampshire and Duroc crossbred pigs from 32·75 kg average weight to 60·2 kg liveweight in a single-way classification bireplicate trial. Average daily feed, average daily gain and feed to gain ratios for the respective diets were 2·19, 2·05 and 2·16 kg; 0·58, 0·60 and 0·61 kg; and 3·88, 3·50 and 3·62. These differences were not statistically significant (P > 0·05). The linear measures and jointed proportions of the carcasses, as well as pig organ weights, were statistically the same for the three test diets. The pigs fed full-fat soya bean however produced soft-fat carcasses. These results suggest that full-fat soya bean, which is appropriately heat-processed, may effectively replace soya bean meal in growing-finishing pig diets.     

Preparation and characterisation of soya milk enriched with isoflavone aglycone fermented by lactic acid bacteria combined with hydrothermal cooking pretreatment

A fermented soya milk (FSM) enriched with isoflavone aglycone (FSM‐SPIA) was prepared from heated soya protein isolate (SPI)‐isoflavone complex. After 48 h of fermentation, FSM‐SPIA contained higher contents of living bacteria, free amino acids and aglycone compared with the FSM of SPI (FSM‐SPI) and the FSM of SPI‐isoflavone complex (FSM‐Mix). In the in‐vitro digestion experiment, FSM‐SPIA showed higher antioxidant capacity and isoflavones (ISO) bioavailability than FSM‐SPI and FSM‐Mix. This was likely due to the soya milk containing a higher level of amino acid, peptides and the presence of soya bean isoflavone. The improved protein digestibility, the interaction and binding ability between proteins and ISO may affect the properties of the protein and the fermented products. The FSM enriched with isoflavone aglycone can be used as a functional fermented drink, as well as an auxiliary food for menopausal women during a specific pathological period.     

The effect of high solid concentrations on enzymatic hydrolysis of soya bean protein isolate and antioxidant activity of the resulting hydrolysates

This study investigated the effect of high solid concentrations on the enzymatic hydrolysis and antioxidant activities of soya bean protein isolate hydrolysates (SPIHs). The soya bean protein isolate at the concentration of 8%, 16%, 24% and 32% was hydrolysed to obtain SPIH with 21.5% degree of hydrolysis (DH), respectively. Results showed that, for the same DH, significant increases in reaction time and decrease in protein recovery were observed as solid concentrations increased. There was no significant difference in molecular weight distribution, but different amino acid compositions in supernatants of SPIH hydrolysed at different solid concentrations. The level of antioxidant amino acids in high solid concentration (32%) was higher than that in low solid concentration group, and antioxidant activity of SPIH increased with the solid concentration increased. Thus, increasing solid concentrations could increase the antioxidant activities and functional properties with low water costs.     

An assessment of commercially available reagents for an enzyme-linked immunosorbent assay (ELISA) of soya protein in meat products

An enzyme-linked immunosorbent assay (ELISA) procedure based on a limited supply of specially prepared experimental immunoreagents and designed to measure levels of soya protein in raw or processed mixed meat products has already been published. This report describes a modified method with commercially available immunoreagents suitable for routine use; its response to a range of commercial soya ingredients has been checked using a particular soya protein isolate (Unisol, Unimills BV) as arbitrary standard. Individual soya components and possible cross-reacting food materials have also been investigated. Both the original and modified methods have been applied to a set of model beefburgers containing known levels of Unisol. There was good agreement between observed and calculated levels in raw and heat-set beefburgers; sterilised samples gave a decreased but linear response. The procedure is recommended for the examination of meat products in non-specialised laboratories.     

Thermal Effects on in vitro Protein Quality of Red Kidney Bean (Phaseolus vulgaris L.)

Significant thermal effects on in vitro protein quality of red kidney beans were observed. Beans autoclaved at 121°for 10 and 20 min, and common home-cooked beans had improved protein quality. Uncooked beans, and those autoclaved at 128°for 20 min and at 121°for 90 min had reduced protein quality compared to canned beans and those autoclaved at 110°for 20 min and at 121°for 40 and 60 min. Amino acid scores, essential amino acid index and available lysine (%), corrected for in vitro protein digestibility gave comparable results in evaluation of protein quality. Specific lysine, methionine, cysteine and other amino acid ratios overestimated protein quality.     

Extraction and physicochemical properties of soya bean protein and oil by a new reverse micelle system compared with other extraction methods

Reverse micelle extraction is a novel technology for the separation of plant components such as proteins and oil. In this study, sodium bis(2‐ethylhexyl) sulphosuccinate (AOT) reverse micelle system and AOT/Tween 85 reverse micelle system were used to extract soya bean protein and oil from soya bean flour. The physicochemical properties of the protein and oil extracted were investigated and compared with traditional extraction methods. The results showed that the efficiency of forward extraction of soya bean protein using an AOT/Tween 85 reverse micelle system was superior to that using an AOT reverse micelle system at the optimal extraction conditions. In addition, soya bean proteins extracted using reverse micelle extraction had no unordered structure under Fourier transform infrared spectroscopy. The acid and peroxide values of oil products from two reverse micelle extractions were lower than that from immersion. The results indicated that AOT/Tween 85 reverse micelle system is effective in extracting soya bean protein and oil.