酱油中氨基甲酸乙酯形成机制、检测技术及控制研究进展

氨基甲酸乙酯是一种无色无臭的结晶体,且广泛存在于发酵食品中的水溶性“2A”级致癌物。该文阐述了氨基甲酸乙酯的致癌机理与形成机制,针对酱油中氨基甲酸乙酯的检测技术及控制措施的研究进展等方面进行综述,同时对其检测手段及减除技术的发展进行展望,以期为氨基甲酸乙酯在酱油制品中的深度研究提供参考。     

Morphology, proliferation, and ribonucleic acid and fractional protein syntheses in the small intestinal mucosa of young goats fed soy protein-based diets with or without amino acid supplementation

The study was designed to examine whether feeding soy protein isolate as partial replacement of casein (CN) affects jejunal protein synthesis and whether effects may be ameliorated by supplementation of those AA known to be at lower concentrations in soy protein isolate than in CN. Goat kids (14 d) were fed comparable milk protein diets, in which 50% of the crude protein was CN (CAS), soy protein isolate (SPI), or soy protein isolate supplemented with AA (SPIA) for 43 d (n = 8 per group). On d 42, plasma concentrations of protein, urea, and AA were measured before and after morning feeding. In the morning of d 43, [¹⁵N]RNA from yeast [13 mg/kg of body weight (BW)] was given with the diet to measure the reutilization of dietary RNA precursors for mucosal RNA biosynthesis. Four hours later, an oral dose of l-[1-¹³C]leucine (180 mg/kg of BW) was administered and blood samples were collected between −15 and +45 min relative to tracer administration for analysis of plasma ¹³C α-ketoisocaproic acid and ¹³C recovery in blood CO₂. Kids were killed 60 min after the tracer application, and jejunal tissue was collected to determine mucosal morphology, cell proliferation, enzyme activities, RNA synthesis, and fractional protein synthesis rate. Plasma protein concentrations were higher in CAS than in SPI and SPIA. Plasma concentrations of Thr were higher in CAS than in SPI and SPIA, and those of Met were lower in SPI than in CAS and SPIA. In mid-jejunum, villus circumferences were higher in CAS than in SPI and SPIA, and villus height and villus height:crypt depth ratio were higher in CAS than in SPI. In mid-jejunum, mucosal protein concentrations were higher in CAS than in SPI and SPIA and mucosal activities of aminopeptidase N tended to be higher in CAS than in SPI, whereas activities of dipeptidyl peptidase IV tended to be lower in SPI than in SPIA. Activities of 5′ nucleotidase and xanthine oxidase were lower in CAS than in SPI. The ¹³C recovery in blood CO₂ tended to be higher in SPI than in CAS. In mid-jejunum, ¹⁵N enrichment of RNA tended to be higher in CAS than in SPI, and ¹³C enrichment of protein-bound Leu was higher in SPI than in CAS. In mid-jejunum, the fractional protein synthesis rate tended to be higher in SPI than in CAS. Our results revealed changes in intestinal growth after soy protein feeding that were associated with effects on intestinal RNA and protein synthesis but that were not ameliorated by AA supplementation.     

几种多糖和交联剂对可食性大豆分离蛋白膜性能的影响

为了提高可食性大豆分离蛋白膜的性能,研究了多糖和交联剂对可食性膜性能的影响。结果表明,在大豆分离蛋白成膜液中添加0.5%(W/V)的果胶能有效增加膜的机械强度,添加0.1%(W/V)的葡萄糖能有效降低膜对水蒸气、氧气的透性。因此,果胶和葡萄糖对其性能的改善效果较佳,果胶和葡萄糖能改善大豆分离蛋白成膜特性的可能机理是因为它们增加了蛋白分子之间的交联。     

脱脂大豆粕中提取大豆蛋白、异黄酮、低聚糖和皂甙的工艺方法研究

以脱脂大豆粕为原料,在提取大豆异黄酮的基础上,同时将大豆蛋白、低聚糖和皂甙3种活性成分逐一分离。小试研究表明,从脱脂大豆粕中提取大豆异黄酮的最佳条件为:乙醇浓度40%,酸加量0·15%,温度30℃,时间6h。大豆异黄酮乙醇提取液经回收乙醇、树脂吸附提纯得到含量约20%的大豆异黄酮粗粉。再用浓度为92%的60倍丙酮提纯3次,可得到含量约40%的大豆异黄酮粉。该工艺中大豆粕经乙醇浸提可得到大豆蛋白;树脂吸附后的未吸附液经处理可得到大豆低聚糖;大豆异黄酮经丙酮精制可分离出大豆皂甙。     

Gluten-free quinoa noodles: effects of intermediate moisture extrusion and soy protein isolates supplement on cooking quality and in vitro digestibility

Quinoa is considered as a superior gluten-free material due to its balanced composition of amino acids in protein and abundant nutrients. However, the processing behaviour of quinoa flour is limited by protein functional properties. In this study, twin-screw extrusion was used for the production of gluten-free quinoa noodles (GFQNs). Moisture was found to be closely related to the cooking quality and texture characteristics of extruded noodles by regulating the formation of starch gel. With this in concern, the moisture dose was optimised as 30%. Then, soy protein isolate (SPI) was supplemented into quinoa flour to improve the texture and cooking quality of GFQNs while decrease its in vitro starch digestibility. It was found that SPI could significantly reduce the cooking loss of GFQNs from 16.65% to 11.82% while increase the hardness of the noodles from 6.35 N to 7.99 N, and form a more porous structure as observed by SEM. Furthermore, the addition of SPI also delayed the in vitro hydrolysis rate of quinoa-based noodles, as shown by the significant decrease in rapid digestible starch around 8%. Therefore, quinoa–SPI mixture flour with the intermediate moisture extrusion showed prospective to develop low glycaemic index GFQNs.     

大豆蛋白与酪蛋白比例对搅打稀奶油稳定性影响的研究

研究了大豆蛋白与酪蛋白不同配比对搅打稀奶油乳浊液的表观粘度及搅打过程中的液相蛋白浓度、脂肪部分聚结、搅打起泡率的变化和泡沫稳定性的影响,并在此基础上探讨了其作用机理。结果表明:大豆蛋白比例的增大能增加界面膜的粘弹性,抑制脂肪球的部分聚结,提高泡沫结构的稳定性,当大豆蛋白与酪蛋白比例为4∶1时,搅打稀奶油可以获得最佳的稳定性。     

酱油中总酸度、氨基酸态氮和氯化物连续测定法的研究

对酱油中总酸度、氨基酸态氮和氯化物的测定进行了改进,将几个单独测定的项目合并为一个连续测定,整个测定操作简便,节时省工,一次完成。研究结果表明,一次性连续测定法具有快速、准确等优点,效果显著。     

Effect of adding zein,soy protein isolate and whey protein isolate on the physicochemical and in vitro digestion of proso millet starch

Mixtures of proso millet starch with zein (15%, w/v), soy protein isolate (SPI, 15%, w/v) and whey protein isolate (WPI, 10%, w/v) as starch–protein composites were prepared through heat–moisture treatment, and the effects of protein addition on the physicochemical, structural and digestibility properties of starch were investigated. Rapid Visco Analysis showed that the addition of zein, SPI and WPI gave significantly decreased setback values to 240.7cp, 192.0cp and 83.0cp, respectively, and setback values decreased reflected the excellent cold paste properties. Thermal analysis showed that each protein reduced the enthalpy, but especially WPI (reduced by 94.7%), suggesting that the double helices of the starch granules were decreased. X-ray diffraction showed that starch crystallinity was decreased after protein addition. The digestibility studies revealed that the addition of zein, SPI and WPI decreased the content of rapidly digestible starch and increased the resistant starch content to 8.4%, 14.6% and 17.5%, respectively. The whey protein displayed a more obvious impact on the digestibility of proso millet starch. These results will help guide the production and processing of starchy foods with desirable properties.     

Effect of a soy protein-based diet on ribonucleic acid metabolism in the small intestinal mucosa of goat kids

This study was designed to investigate the effect of soy protein inclusion in milk replacer diets for goat kids on protein, RNA, and DNA contents in small intestinal mucosa, on the importance of RNA biosynthesis from dietary RNA precursors for mucosal RNA synthesis, and on the activities of enzymes involved in nucleotide degradation in small intestinal mucosa. Diets were based on cow's milk. In the control group, 35% of the milk protein was replaced by casein (CN) protein, and in the soy group (SPAA), the same amount of milk protein was replaced by soy protein supplemented with essential AA known to be at lower concentrations in soy than in CN (Thr, Val, Ile, Leu, His, Lys, Met). Diets were isonitrogenous and isoenergetic. At 47 d of age, goats were harvested and samples of proximal, middle, and distal jejunal mucosa were collected 5 h after feeding ¹⁵N-labeled RNA from yeast (13 mg/kg of body weight). Growth and feed conversion did not differ between the control and SPAA kids. Mucosal protein concentrations were lower in the SPAA than the control kids. Concentrations of RNA and DNA did not differ between feeding groups, but in all kids mucosal RNA concentrations were higher in proximal than in middle and distal jejunum. Protein:RNA ratios were higher in the control than the SPAA kids and were lowest in proximal jejunum. Activities of alkaline phosphatase in enterocytes were higher in proximal than in middle and distal jejunum. Activities of mucosal xanthine oxidase were highest in distal jejunum and were higher in the SPAA than the control kids, especially in the middle and distal sites. The ¹⁵N-enrichment of mucosal RNA was higher in the control than the SPAA kids, especially in distal jejunum, and was lowest in distal jejunum. In contrast, ¹⁵N-enrichment of urea in plasma tended to be higher and Gly concentration in plasma was lower in the SPAA than the control kids. Data indicate that protein content and the protein:RNA ratio were lower in jejunal mucosa of goat kids fed milk replacer with partial replacement of CN protein by soy protein. These findings were accompanied by a lower level of reutilization of preformed dietary RNA precursors for RNA biosynthesis in jejunal mucosa and a higher activity of xanthine oxidase. Thus, feeding soy protein instead of CN protein reduced the incorporation of preformed dietary RNA precursors for RNA biosynthesis in the mucosa and activated key enzymes involved in nucleic acid breakdown.     

Effects of inulin/oligofructose on the thermal stability and acid-induced gelation of soy proteins

ABSTRACT:  Differential scanning calorimetry (DSC) and dynamic oscillatory shear testing were performed to study the influence of inulin (Raftiline^® HP-gel and Raftiline^® ST-gel) and oligofructose (Raftilose^® P95) on the thermal stability and gelation (using glucono-δ-lactone [GDL] as a coagulant) of soy protein isolate (SPI) dispersions. Addition of 10% (w/v) inulin/oligofructose or sucrose increased ( P < 0.05) the peak denaturation temperatures ( T_m ) of 7S and 11S soy proteins in SPI dispersion (5%[w/v], pH 7.0) by an average of 1.9 and 2.3 °C, respectively. GDL induced SPI thermal gelation, and the gel rheology was affected by both the pH decline and the specific temperature of heating. Addition of inulin/oligofructose (8%, w/v) improved the gelling properties of preheated SPI dispersion (8%, w/v) coagulated with GDL, showing 14.4 to 45.6% increase ( P < 0.05) in gel rigidity ( G ' value) at the end of heating (81 °C). Microstructural examination revealed a denser protein cross-linking structure and reduced pore sizes in SPI gels containing inulin/oligofructose. In general, inulin was more capable of improving SPI gelation than oligofructose, suggesting that the degree of fructose polymerization in the fructans was of thermal and rheological importance.     

不同来源蛋白酶水解对大豆分离蛋白分散性及溶解性的影响

研究了动物(胰蛋白酶)、植物(木瓜蛋白酶与菠萝蛋白酶)、微生物(碱性蛋白酶和中性蛋白酶)三种来源蛋白酶的低限度水解对大豆分离蛋白(SPI)分散性和溶解性的影响。结果表明,三种来源蛋白酶轻度水解可显著提高SPI的分散性,但却使其溶解性有不同程度的降低。三种来源蛋白酶水解产物的分散度大小依次为:植物来源蛋白酶>微生物来源蛋白酶>动物来源蛋白酶,而其溶解性则相反:动物来源蛋白酶>微生物来源蛋白酶>植物来源蛋白酶。本文对采用酶解的方法制备高分散性与高溶解性SPI具有一定的参考价值。通过对木瓜蛋白酶水解沉淀物进行分析,可以推测酶解使SPI溶解度显著下降的原因可能是SPI被水解后通过疏水作用力和氢键相互聚集形成了不溶性的沉淀。     

亚油酸氢过氧化物氧化修饰对大豆蛋白热变性和聚集的影响

以亚油酸氢过氧化物代表脂质氢过氧化物氧化修饰大豆分离蛋白,采用圆二色光谱、内源荧光光谱、粒径分析以及相对分子质量分布研究氢过氧化物氧化修饰对大豆蛋白热变性和聚集的影响.结果发现亚油酸氢过氧化物氧化修饰使得大豆蛋白热稳定性下降,热变性过程中形成聚集体粒径随着蛋白质氧化程度的升高呈现先增加后减小的趋势,热变性大豆蛋白冷却后的粒径和聚集体含量则随着蛋白质氧化程度的增加而下降.     

几种含氮物质对酱油氨基酸态氮及全氮测定值的影响

按GB 18186-2000酱油检测方法测定几种含氮物质的氨基酸态氮值及测定添加了1％这些含氮物质的酱油氨基酸态氮及全氮含量,分析这些含氮物质对酱油测试结果的影响情况,结果表明:无机铵(氯化铵、硫酸铵),有机铵(柠檬酸铵、草酸铵)等均会导致酱油氨基酸态氮测定值偏高,而三聚氰氨和尿素对酱油的氨基酸态氮测定值无影响;以上几种含氮物质均会提高酱油全氮的测定值.     

食品中牛乳蛋白质和大豆蛋白质结构对比研究

对牛乳蛋白质和大豆蛋白质的结构进行了对比研究。结果表明,两类蛋白质在组分组成、溶解性、分子大小、氨基酸组成等方面差异明显,特别是具有特征紫外吸收波长的氨基酸残基数差异明显。对比了大豆蛋白质和牛乳蛋白质组分中苯丙氨酸(Phe)、色氨酸(Trp)和酪氨酸(Tyr)残基数,比较了各蛋白质组分的Phe/Trp Tyr比例。通过比较各组分Phe/Trp Tyr比例,发现除β-酪蛋白外,大豆蛋白质组分与牛乳蛋白质相比,苯丙氨酸含量明显大于色氨酸和酪氨酸量的总和。     

Effect of substitution of soy protein isolate on aroma volatiles, chemical composition and sensory quality of wheat cookies

Wheat flour was substituted with soy protein isolate (SPI) at levels of 0–20% and its effect on aroma volatiles and quality of cookies was evaluated. The chemical analysis showed that the moisture and protein content increased gradually by increasing the added levels of SPI whereas the carbohydrate and fat levels showed the opposite trend. The sensory characteristics, aroma, taste, crispiness and overall acceptability showed significant ( P  <   0.05) increase of up to 10% SPI substitution compared with cookies free of SPI. The gas chromatographic-mass spectrometric (GC-MS) analysis of aroma volatiles revealed that the sample containing 10% SPI had the highest yield (13.57%) of pyranones, the key odourants of cookies. The results of GC-MS analysis were consistent with those of the aroma sensory analysis of cookies during storage.     

Effect of free or protein-associated soy isoflavones on the antioxidant status in rats

BACKGROUND: The objective of this study was to investigate the effect of chronic ingestion of free and protein‐associated soy isoflavones on the antioxidant status in male Wistar rats. Free isoflavone (iso), protein‐associated soy isoflavone (iso + prot) and soy protein (prot) extracts were administered for 30 days by gavage to the rats at a dosage of 1 mg aglycone isoflavones per 200 g body weight, adjusted daily, and the prot group was given the same concentration of soy protein received by the iso + prot group. Antioxidant capacity of plasma, thiobarbituric acid‐reactive substance (TBARS) and glutathione (GSH) levels and catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities in plasma, erythrocytes and tissues and gene expression levels in liver and kidney were evaluated. RESULTS: Chronic ingestion of free but not of protein‐associated soy isoflavones nor of solely soy protein increased plasma antioxidant capacity and GPx activity in erythrocytes. Soy protein increased CAT activity and gene expression in liver. SOD activity in erythrocytes was increased by all treatments. CONCLUSION: The overall results confirm that dietary soy isoflavones have a positive effect on antioxidant status, enhancing antioxidant capacity of plasma and antioxidant enzymes in various tissues, but the effects are dependent on the form of administration and on a complex mechanism of antioxidant status balance on the organism. Copyright © 2010 Society of Chemical Industry