The application of wheat fibre and soy isolate impregnated with iodine salts to fortify processed meats

The aim was to use wheat dietary fibre and soy protein isolate as carriers of KI and KIO₃ for fortification of processed meat with iodine. Products from minced pork were prepared with addition of iodised wheat fibre and soy isolate, and iodised table salt for comparison and the effects of thermal processing and storage on changes in iodine content were determined. It was shown that both alternative carriers limited the iodine changes in meat products compared with iodised table salt. However, wheat fibre was more effective in limiting iodine losses during thermal processing and soy protein during storage of the products. The greatest effect of the carriers was found in meat products fortified with the less stable KI.     

The application of wheat fibre and soy isolate impregnated with iodine salts to fortify processed meats

The aim was to use wheat dietary fibre and soy protein isolate as carriers of KI and KIO₃ for fortification of processed meat with iodine. Products from minced pork were prepared with addition of iodised wheat fibre and soy isolate, and iodised table salt for comparison and the effects of thermal processing and storage on changes in iodine content were determined. It was shown that both alternative carriers limited the iodine changes in meat products compared with iodised table salt. However, wheat fibre was more effective in limiting iodine losses during thermal processing and soy protein during storage of the products. The greatest effect of the carriers was found in meat products fortified with the less stable KI.     

大豆分离蛋白在成膜后的营养特性变化

采用胃蛋白酶和2，4，6-三硝基苯磺酸分别测定大豆分离蛋白膜的消化率和赖氨酸有效性。结果表明，蛋白质的消化率和赖氨酸有效性随成膜溶液的pH升高而下降，并因一些增加蛋白交联的物质如单宁、阿魏酸和过氧化氢的添加而降低。蛋白膜的机械性与膜蛋白消化率和赖氨酸有效性存在一定负相关，即机械性能较强的膜，其消化率和赖氨酸有效性较低。不过，玉米淀粉似乎是个例外，它在改善机械特性的同时，也保持了大豆蛋白膜的营养。由于大豆分离蛋白制备成膜后，其消化率和赖氨酸有效性下降，因此将大豆蛋白膜称为生物可降解膜似乎比称作可食性膜更科学。     

Factors affecting production of melon seed kernel protein: Yield,composition and protein isolates quality

Extraction and precipitation were investigated to determine the opti-mal conditions for preparation of protein concentrates from defatted melon seed kernels flour. Protein concentrates were prepared by extraction with distilled water, salt or alkaline solution. Alkaline so-lution led to the highest extraction yield of 84.5%. The protein concen- trate has a good digestibility of 90.8% as determined by in vitro enzy-matic method. The protein is rich in lysine 6.35% but poor in sulphur-containing amino acids such as methionine 0.27%, and cystine 0.33%. The protein isolate showed good whipping and emulsifying character-istics as well as water and oil absorptions.     

Sulfur Amino Acid Stability. Effects of Processing on Legume Proteins

Four legume protein sources: peanuts, dry beans, alfalfa and soybeans were processed in laboratory, pilot plant and commercial processing facilities. Raw ingredients, intermediate and final protein products were analyzed for total and reactive cysteine/cystine (Cys), total methionine, methionine sulfoxide and methionine sulfone. Lysine, total and reactive, was determined on each legume protein sample. Processing of soybeans, peanuts and alfalfa into protein products caused no significant loss of lysine or the sulfur amino acids. The production of a protein concentrate from dry beans resulted in a significant loss of Cys. One commercial soy isolate was found to contain 51% of its total methionine as methionine sulfoxide, yet its Cys was unaffected.     

Influence of Protein Source, Type, and Concentration, and Product Form on the Protein Quality of Commercial Enteral Formulas

ABSTRACT: The total, protein, and nonprotein nitrogen, 3 amino acids (lysine, histidine, and tyrosine), available lysine, and in vitro protein digestibility in enteral formulas were determined. Available lysine and protein digestibility were lower in the liquid formulas tested than in the powdered formulas. The protein quality of the formula made from soy protein isolate (soy) was lower than that of the formulas made from casein, and the protein quality of a low-protein formula was lower than that of the standard formulas. There was a statistically significant correlation between the available lysine content and protein digestibility in the polymeric formulas. New methods are required for assessing the protein quality of formulas containing hydrolyzed proteins.     

Effect of alkaline pH-shift processing on in vitro gastrointestinal digestion of herring (Clupea harengus) fillets

The effect of alkaline pH-shift processing on herring (Clupea harengus) protein oxidation, salt solubility and digestibility, has been evaluated. For the latter, herring mince and pH-shift produced herring protein isolate, both raw and heat-treated, were digested using a static gastrointestinal in vitro model. The pH-shift process resulted in drastically lowered protein salt solubility and increased lipid oxidation while protein carbonyl formation was unaffected. Yet, no significant differences in the degree of hydrolysis (DH) were observed between mince and isolates after completed gastrointestinal digestion, something which was confirmed by a similar release of proteinaceous material <3 kDa and similar free amino acid profiles. The polypeptide profiles of digested samples however revealed that two peptides (33 and 36 kDa) were present in larger amounts in the digested protein isolate compared to the digested herring mince. The results indicate that alkaline pH-shift processing had limited quantitative influence on the gastrointestinal digestibility of herring proteins despite its negative effects on protein salt solubility and lipid oxidation.     

鸡内金炮制品对大豆分离蛋白体外消化特性的影响

该研究以鸡内金炮制品为原料,通过对消化率、酶活性、粒径大小以及相对分子质量分布的分析,比较不同方法制备的鸡内金炮制品对大豆分离蛋白体外消化特性的影响。结果表明：在不加外源酶时,鸡内金炮制品中的蛋白酶可能是引起蛋白质降解的主要原因。在加入外源蛋白酶时,添加鸡内金能提高大豆分离蛋白消化率,炮制品对蛋白质消化率的影响效果依次为：麸炒>醋炒>生品>砂炒>清炒,炮制品对蛋白质消化率的影响效果与其对酶活性的促进效果一致。麸炒和醋炒鸡内金在消化1 h时对蛋白质消化率的促进消化最显著,使大豆分离蛋白消化率由36.78%提高到41.33%和40.99%。体外消化表征结果也表明,添加鸡内金也会使蛋白质消化产物粒径减小、粒径分布的最大峰值左移、蛋白质相对分子质量分布向小分子范围偏移。鸡内金对消化产物的影响主要发生在消化前1 h内。该研究为鸡内金的深入研究提供新思路。     

Nutritional Evaluation of the Protein in Oilseed Products Heated with Sugars

Defatted flours and protein isolates from glandless cottonseed, peanut, and soybean were complexed with glucose or sucrose in a ratio of 1:1 by weight and heated at 100°C for 0, 2, or 6 hr. Quality changes by the heat treatment were assessed by determining the extent of browning (browning index), in-vitro protein digestibility, available lysine total amino acids, and computed protein efficiency ratio (C-PER). Whereas the sucrose-containing complexes changed very little in all the quality parameters determined, the counterparts containing glucose decreased substantially in protein quality along with the increased intensity of browning. Before heating, protein digestibility of the complex containing defatted flour of an oilseed was lower than that of the isolate counterpart. When heated, however, the isolate-glucose complexes decreased more in protein digestibility than the flour-glucose complexes. The available lysine content decreased by 76-83% for the complexes with glucose in contrast with 2-10% for those with sucrose. As to total amino acids, marked losses in arginine, lysine, tryptophan, and histidine were found in the complexes containing glucose, with the arginine loss as high as the lysine loss. Lysine-rich soy proteins lost lysine in greater percentages than lysine-poor peanut and cottonseed proteins. C-PER decreased by 63-86% in the glucose-containing complexes, with the highest decrease shown for soy flour-glucose. In-vitro protein digestibility, available lysine, and C-PER were all highly correlated (P < 0.01) with browning index. Available lysine was also highly correlated with C-PER.     

氧化对大豆蛋白结构、乳液稳定性及消化特性的影响

以大豆分离蛋白为原料,以脂质过氧化产物丙二醛（malondialdehyde,MDA）为氧化引发剂,逐级研究氧化对大豆蛋白结构、乳液稳定性及乳液消化特性的影响。结果发现：随着MDA浓度的升高,蛋白羰基及席夫碱含量明显升高而巯基含量显著降低。同时,MDA可促进蛋白聚集并诱导β-伴大豆球蛋白（7S）组分形成二硫键和非二硫键诱导的共价交联。进一步制备O/W型乳液,发现不同浓度MDA处理蛋白对乳液的形成影响较小,但可以显著改变界面蛋白组成。其中经中高浓度（2.5～10 mmol/L）MDA氧化后,更多7S组分以聚集状态参与界面组成。体外模拟胃肠道消化实验进一步表明,乳液消化主要在肠道进行,氧化诱导的蛋白交联/聚集可延缓或降低胆盐在界面的替代,进而减缓乳液消化并降低脂质释放率。     

Organoleptic and nutritional evaluation of wheat breads supplemented with soybean and barley flour

Supplementations of soy (full fat and defatted) and barley flours to wheat flours at 5, 10, 15 and 20% levels were carried out to test the effects on organoleptic and nutritional evaluation of the supplemented bread. Additions of 15% barley flour, 10% soy flour (full fat and defatted), 15% barley plus full fat soy flour and 15% barley plus defatted soy flour to wheat flour produced acceptable breads. However, substitution of soy (full fat and defatted) and barley flours to wheat flour separately and in combinations at 20% levels did not produce organoleptically acceptable bread. Various nutritional parameters, such as protein, fat, total lysine, protein digestibility (in vitro), sugars, starch digestibility (in vitro), total and available minerals, antinutrients, dietary fibre and β-glucan were determined in supplemented and control bread. Increasing the level of substitution from 5 to 10% of full fat and defatted soy flour to wheat flour significantly (P<0.05) increased protein (from 12.1 to 13.7 and 12.4 to 13.8%), lysine (from 2.74 to 3.02 and 2.76–3.05 mg/100 g protein) and total calcium (from 70.2 to 81.4 and 71.9–81.8 mg/100 g) contents. However, there was also an increase in phytic acid (238–260 and 233–253 mg/100 g), polyphenol (324–331 and 321–329 mg/100 g) and trypsin inhibitor activity (193–204 and 193–198 TIU/g). When barley flour was substituted separately, and in combinations, with full fat and defatted soy flour up to 15%, this significantly increased the contents of protein, total lysine, dietary fibre and β-glucan. It may be concluded that breads supplemented with barley and defatted soy flour, up to a 15% level, are organoleptically and nutritionally acceptable.     

Effect of Partial Methionine Oxidation on the Nutritional Quality of Soy Isolate and Casein

The bioavallabllity of methionine sulfoxide residues in two food proteins, casein and soy isolate, was determined in weanling (21- day-old) and mature rats (101-day-old). Methionine sulfoxide residues within these two proteins had no significant effect on protein digestibility in either group of rats or on the growth of mature rats, but slowed the growth of weanling rats. The impact of methionine sulfone on the protein efficiency ratio (PER) bioassay for protein nutritional quality, which uses weanling rats, was also measured. Results from this study indicated that for each 10% of the methionine residues which are present as partially oxidized methionlne sulfone, the PER of the protein is lowered by 0.085 units.     

Effect of soy flour addition and heat-processing method on nutritional quality and consumer acceptability of cassava complementary porridges

BACKGROUND: The nutritional quality of cassava complementary porridge was improved through extrusion cooking and compositing with either defatted or full fat soy flour (65:35 w/w), and product acceptability by mothers with children of the target population was evaluated. RESULTS: The protein digestibility‐corrected amino acid score (PDCAAS) of extrusion‐ and conventionally cooked composite porridges was within the recommendations for complementary foods. The kinetics of starch digestibility showed that all porridges had a rapid rate of starch digestibility, but the rate was lower when defatted soy flour was added and lowest when full fat soy flour was added. The formation of amylase‐lipid complexes as shown by X‐ray diffraction and differential scanning calorimetry can be attributed to the lower digestibility of extrusion‐cooked porridge with full fat soy flour. If fed thrice per day, extrusion‐cooked porridge with defatted or full fat soy flour would meet the energy, protein and available lysine requirements of a child aged 6–8 months receiving low or average nutrients from breast milk. All porridges were well received by Mozambican mothers who use cassava as a staple food. The mean scores for sensory liking of all porridges were 3 and above on a five‐point hedonic scale. CONCLUSION: Extrusion‐cooked cassava/soy flour porridges have good potential for use as high‐energy/high‐protein complementary foods and have acceptable sensory properties. Copyright © 2012 Society of Chemical Industry     

Rice Dreg Protein as an Alternative to Soy Protein Isolate: Comparison of Nutritional Properties

Rice dreg protein could be a valuable source of plant-based proteins, as an alternative to soy proteins in some food products. Here, nutritional properties of rice dreg protein were compared with those of soy protein isolate. The protein content of rice dreg protein was approximately 62.6 g/100 g sample, with large amounts of fat, carbohydrate, and ash. The denaturation temperatures of rice protein isolate from rice dreg protein were 47.4 and 97.2°C, respectively. This indicated that these proteins could be denatured during rice syrup processing to form aggregates, but were relatively more stable than rice endosperm protein and soy protein isolate. The main amino acids in rice dreg protein and rice protein isolate were Glu, Pro, Arg, Asp, and Leu, with Lys as the lowest content. Most of essential amino acids and nutritional parameters of rice protein isolate and rice dreg protein met the suggested nutritional requirements for a child according to FAO/WHO, and were relatively higher than those of soy protein isolate. In addition, rice protein isolate showed better digestibility than soy protein isolate during four hours sequential pepsin and pancreatin digestions. The final digestibility value was 96.66% for rice protein isolate compared to 91.41% for soy protein isolate. Thus rice dreg protein could potentially replace soy proteins as a good source of value-added protein for human nutrition in response to the increasing demand for plant proteins.     

Effect of Defatted Soybean and Soybean Isolate Fortification on the Nutritional, Physical, Chemical and Sensory Properties of Wheat Flour Tortillas

Wheat flour fortified with 11.1% defatted soybean meal (SBM) or 5.6% soybean isolate (SBI) was processed into flour tortillas. Fortified tortillas contained 35% more protein and twice as much lysine as the 100% wheat flour tortilla. Addition of SBM or SBI decreased dough elasticity but increased dough water absorption and the force required to stretch the dough. The SBM fortified tortilla had better texture (P < 0.05) than the 100% wheat flour tortilla and similar flavor and color (P > 0.05). Rats fed fortified tortillas gained three times as much weight and doubled the protein efficiency ratio (PER) when compared to rats fed wheat flour tortillas. The apparent biological and net protein utilization values of the fortified tortillas were similar (P > 0.05) and higher (P < 0.05) than the wheat flour tortilla. The SBI fortified tortilla had a higher apparent protein digestibility (P < 0.05) than the 100% wheat flour and SBM fortified tortillas.     

大豆分离蛋白粉对面团流变学特性和馒头品质的影响研究

将大豆分离蛋白粉作为一种食品添加剂添加到小麦粉中,研究其对面团流变学特性和馒头品质的影响。实验结果得出,在小麦粉中添加大豆分离蛋白粉,可以明显地改善面团的稳定时间以及拉伸曲线面积和拉伸阻力。另外还可以提高馒头的品质,当在小麦粉中添加3%的大豆分离蛋白粉时,其对馒头品质有较好的改善作用。     

Functional Properties and Oxidative Stability of Flaxseed Oil Microencapsulated by Spray Drying Using Legume Proteins in Combination with Soluble Fiber or Trehalose

The objective of this study was to evaluate the potential of double wall material combinations, using legume protein (soy protein isolate and pea protein isolate) in combination with wheat dextrin soluble fiber or trehalose, as alternative materials for microencapsulation of flaxseed oil by spray drying. The obtained preparations, with oil content of 35%, were fine and difficult flowing powders, regardless of their composition. The 1% addition of silica to the powders significantly reduced their cohesiveness and improved their flowability. The efficiency of microencapsulation, calculated based on oil fat content, ranged from 62 to 98% and was higher in the powders with trehalose and in the powders containing soy protein. Effective protection against oxidation of microencapsulated oil was achieved in the protein-trehalose matrix, especially in the case of the vacuum-packed powders with pea protein during storage at refrigeration temperature. Replacing trehalose with soluble fiber enabled formation of powders less susceptible to caking under conditions of increased humidity, but it resulted in decreased microencapsulation efficiency. The combination of pea protein/carbohydrate resulted in the formation of microcapsules with porous structure, especially in the system with soluble fiber. With time, the structure of the primary emulsions and those reconstituted from powders containing pea protein changed from liquid to greasy and paste-like.     

The protein quality of some Indian dishes prepared from wheat

The protein quality of Indian dishes prepared from whole wheat and refined wheat flour were measured in N-balance experiments with growing rats. All samples were also analysed for amino acids. The levels of lysine, methionine, cystine and tryptophan were slightly reduced by processing. As a result, with the exception of a dish prepared by deep fat frying, the net protein utilisation of the dishes were approximately 5% lower than those of the corresponding unprocessed samples. True digestibility, however, was in general only slightly influenced by the processing.     

Biochemical studies of some non-conventional sources of protein. Part 5. Extraction and characterization of protein from fenugreek seed (Trigonella foenum L.)

Protein concentrates were prepared from fenugreek seeds by extraction with distilled water, salt solution and alkaline solution. Alkaline solution resulted in the highest extraction yield (82%). The protein concentrate has a good digestibility (over 90%) as determined by in vitro enzymatic method. The protein is rich in lysine (6.51%) but poor in sulphur-containing amino acids such as methionine (0.71%), cystine (1.09%) and tryptophan (1.03%).