IMP2, a nuclear gene controlling the mitochondrial dependence of galactose, maltose and raffinose utilization in Saccharomyces cerevisiae.

The IMP2 gene of Saccharomyces cerevisiae is involved in the nucleo-mitochondrial control of maltose, galactose and raffinose utilization as shown by the inability of imp2 mutants to grow on these carbon sources in respiratory-deficient conditions or in the presence of ethidium bromide and erythromycin. The negative phenotype cannot be scored in the presence of inhibitors of respiration and oxidative phosphorylation, indicating that the role of the mitochondria in the utilization of the above-mentioned carbon sources in imp2 mutants is not at the energetical level. Mutations in the IMP2 gene also confer many phenotypic alterations in respiratory-sufficient conditions, e.g. leaky phenotype on oxidizable carbon sources, sensitivity to heat shock and sporulation deficiency. The IMP2 gene has been cloned, sequenced and disrupted. The phenotype of null imp2 mutants is indistinguishable from that of the originally isolated mutant.     

Production of soya milk containing low flatulence‐causing oligosaccharides in a packed bed reactor using immobilised α‐galactosidase

Peanut α‐galactosidase was immobilised in calcium alginate beads and used to hydrolyse the flatulence‐causing oligosaccharides, raffinose and stachyose, in soya milk in batch and in packed bed reactor with recycle. The immobilised enzyme exhibited a slightly lower activity than the free enzyme. The activity yield of immobilised α‐galactosidase was 75.1% and the immobilisation yield was 82.6%. Batch hydrolysis using immobilised enzyme at 55 °C resulted in 96% reduction in the oligosaccharides after 12 h. For the continuous process, a packed bed reactor with recycle was used. More than 98% of the oligosaccharides were hydrolysed after 6 h of reaction at 55 °C. The immobilised enzyme also proved to be stable up to three repeated hydrolysis reactions.     

益生菌降解大豆源α-低聚糖和醛类物质的研究

从传统乳酸菌中分离获得6株产α-半乳糖苷酶的益生菌,研究了它们分解代谢豆乳中α-低聚糖和醛类物质的特性。首先分析了益生菌所产α-半乳糖苷酶的活性;接着探讨了益生菌在豆乳中37℃培养48 h期间,样品中α-低聚糖代谢水平,醛类物质的降解率。pH值变化和蛋白水解活性。结果表明,益生菌表现出不同的α-半乳糖苷酶的活性,乳双歧杆菌B12.0501所产α-半乳糖苷酶活性最高,达到21.8U/mL。豆乳中α-低聚糖和醛类物质的降解程度依赖于菌株类型和发酵时间。     

Content of low molecular weight carbohydrates in vining peas (Pisum sativum) after blanching and freezing: effect of cultivar and cultivation conditions

The content of low molecular weight carbohydrates (LMWC, glucose, fructose, sucrose, raffinose, stachyose and verbascose) was investigated in 29 cultivars of vining peas after blanching and freezing. The peas were harvested at about the same degree of ripeness. There was a positive correlation between the amount of raffinose, stachyose and sorbitol, while a high content of verbascose only could be seen when there was a low content of these sugars. High concentrations of sucrose were generally associated with high concentrations of glucose and fructose. Samples from 1999 had a significantly (p < 0.001) higher content of raffinose, stachyose and sorbitol and lower of verbascose, probably because of the drier and warmer summer that year compared with 1998. Furthermore, medium and late maturing cultivars contained larger amounts of raffinose, stachyose and sorbitol than early cultivars, possibly due to the fact that these cultivars, to a greater extent, were exposed to a higher temperature and more intense sunlight for a longer time. Considerable differences in the content of LMWC could be seen both between the different cultivars and the various trials. Glucose and sucrose were generally similarly affected by cultivar and cultivation conditions, while cultivation conditions had a greater influence on the content of sorbitol and the raffinose family oligosaccharides (RFO; raffinose, stachyose, verbascose) in late‐maturing groups. It is concluded that many factors affect the content of LMWC in peas. However, as the content of RFO is comparatively small in vining peas, any nutritional significance of these sugars in the human colon is probably rather small. Copyright © 2004 Society of Chemical Industry     

高效液相色谱法测定小麦胚中的棉籽糖

研究了采用高效液相色谱法测定小麦胚中的棉籽糖。样品经粉碎、振荡、萃取、过滤等前处理，通过色谱柱进行分离，流动相为64％的乙腈和36％的重蒸馏水。棉籽糖的浓度在10－50μg/mL的范围内能被定量测定，其回收率为99．71％，变异系数为1．89％。     

脱脂棉籽粕中棉籽糖提取方法的研究

棉籽糖是植物界中存在的低聚糖中含量仅次于蔗糖的低聚糖,提取主要是以甜菜糖蜜为原料,而从棉籽粕中提取棉籽糖的研究则较少.对棉籽粕中棉籽糖的浸出工艺进行了研究,通过对提取温度,乙醇溶液浓度和提取料液比等影响因素的分析,得出最佳工艺条件为:提取温度50℃,料液比为1:14(W/V),乙醇浓度为75%.在此工艺条件下,棉籽糖的浸出率为95%.提糖后的棉籽粕中游离棉酚含量由原来的0.085%降低到0.029%,低于FAO所规定的0.04%的食用标准.     

棉籽低聚糖—棉籽糖研究概况

该文综述棉籽低聚糖―棉籽糖性质、各种功能、制备与检测及应用,并对其开发应用前景进行展望。     

大豆低聚糖的生理功能研究进展

大豆低聚糖是豆科种子中可溶性寡糖的总称,近年来由于其中水苏糖和棉籽糖具有显著的抗肿瘤、改善胃肠道环境、调节血脂等功能而备受广大研究人员青睐。一直以来,人们都认为豆类会产生胀气,另一方面,豆类会产生益生元效应并改变大肠茵群,反过来作用于胃肠道系统,同时,近年来很多实验也证明饮食中的豆类摄取不会引起胀气。至今为止也没有学者研究得出豆类的耐受水平。对水苏糖和棉籽糖的深入研究不仅能为研制和开发新型功能性大豆制品提供理论基础,还能正确引导人们进行合理的日常饮食。本文主要综述了豆类中水苏糖和棉籽糖的理化性质和生理功能,特别是近些年其与胀气反应关系的最新研究进展。     

Oligosaccharides, Antinutritional Factors, and Protein Digestibility of Dry Beans as Affected by Processing

Dry beans (Phaseolus vulgaris) were subjected to soaking, cooking or a combination of both prior to fermentation, and then assessed for oligosaccharides, antinutritional factors and in-vitro protein digestibility. Results showed an important decrease in raffinose oligosaccharides and antinutritional factors. However, an increase of trypsin inhibitor and tannin contents occurred respectively in cooked or soaked-cooked fermented beans and in raw or soaked fermented beans. Appreciable improvement in in-vitro protein digestibility was only observed in cooked or soaked-cooked beans. After fermentation, the largest decreases were observed in soaked-cooked beans (92.75%) for raffinose, in cooked beans (31.57%) for phytic acid, in soaked beans (90.86%) for stachyose, and in raw beans for trypsin inhibitor (38.77%). The highest increase due to fermentation was observed in raw beans for in-vitro protein digestibility (1.73%).     

薄层色谱-苯酚硫酸法分析大豆低聚糖中棉籽糖含量

目的：采用比色法建立一种适用于大豆低聚糖中棉籽糖快速检测的方法。方法：运用薄层层析技术分离单糖与低聚糖,展开剂为V(乙腈):V(冰乙酸):V(水)=6:3:2,显色剂为苯胺- 二苯胺- 磷酸,点样量为5μL,层析显色后,苯酚- 硫酸法比色测定。结果：薄层层析可将大豆低聚糖中蔗糖、棉籽糖和水苏糖等组分分开,通过苯酚- 硫酸法分析其中的棉籽糖,线性范围为20～80mg/mL(R2=0.9932),精密度RSD 为1.56%,平均加样回收率为98.14%,RSD 为3.99%。结论：以薄层层析- 苯酚- 硫酸法检测食品或大豆低聚糖中棉籽糖含量,测定结果与HPLC 法对照,相对误差为3.22%,可用于大豆低聚糖中棉籽糖的检测。