脱脂和重组对面粉理化特性和烘焙品质的影响

选用3个筋力不同的小麦品种（系）,通过比较其采用脱脂面粉、重组面粉和原面粉,研究了小麦脂类对面团揉混特性和面包加工品质的影响。结果表明,（1）3个品种（系）面粉脱脂前后蛋白质含量、沉淀值和灰分含量无显著性差异,但脱脂后面粉白度显著提高。（2）脱脂后3个品种（系）揉混仪峰高和峰宽增大,衰落角变小。（3）面粉脱脂后面包加工品质有所改善,其作用大小与蛋白质的质量和蛋白质间的互作有关。脱脂面粉加入起酥油对面包品质无明显改善作用,起酥油是通过面粉脂类对面包品质产生作用的。     

Fractionation of cereal flour by sedimentation in non-aqueous systems. II. Rheological characterisation and baking performance of the protein fraction

A previously described method for the non-aqueous fractionation of cereal flours by sedimentation in non-aqueous solvents was carried out using flours of three wheat cultivars differing in baking performance, as well as one rye and one barley flour. The method was based on differences in the densities of starch (higher) and protein (lower). Thus, suspending finely milled flour in an inert solvent mixture with a density in between the densities of starch and protein yielded a sedimented starch fraction and a protein-rich fraction at the surface of the solvent. Further purification of this upper fraction provided a protein fraction, a middle fraction, and a lipid fraction. The protein fractions were examined by means of rheological methods such as micro-extension tests and creep-recovery tests. They also were reconstituted to standard flour with a protein content of 13.5%, which was used for micro-scale baking tests. Compared to aqueous isolated gluten, the hydrated protein fractions from wheat were much more extensible and had a lower resistance to extension. The baking performance of the wheat protein fractions was superior to gluten and comparable to the native wheat flours. The protein fraction from rye gave a wheat-like bread crumb, whereas the barley protein was not suited for bread making.     

藻蓝蛋白α亚基裂合酶的分子克隆和酶动力学研究

为了比较研究不同藻种中藻蓝蛋白裂合酶CpcE/F的结构与功能的差异,对Anabaena sp.PCC 7120中的CpcE/F进行克隆,并进行大量表达,将表达的裂合酶CpcE/F用于藻蓝胆素(PCB)与Mastigocladus laminosus PCC 7603藻蓝蛋白α-亚基(α-PC)脱辅基蛋白(CpcA)的体外重组,得到天然活性的α-PC,从而表明CpcE/F所编码的蛋白质是α-PC生物合成的裂合酶,并对CpcE/F的酶动力学进行了初步研究。     

Microwave drying of selected greens and their sensory characteristics

Green leafy vegetables which supply minerals and vitamins to the diet, are highly perishable. Therefore, post harvest losses are extremely high. Limited studies are available in the literature with regard to preservation of greens.The effect of microwave drying and storage on physical and sensory properties of selected greens (coriander, mint, fenugreek, amaranth and shepu) were therefore studied. Microwave drying was carried out at 100% power and a frequency of 2450 mHz. The drying time varied from 10 to 16 min for different greens. Microwave drying affected color, appearance and odor of all the greens. The relative reconstitution capacity (RRC) for different greens was coriander-10.3, mint-10.3, amaranth-38.3, fenugreek-31.7 and shepu-32.8. The RRC appeared to influence acceptability. Coriander and mint, which exhibited the lowest RRC (10.3%), had the lowest scores for flavor and color while amaranth, with the highest RRC (38.3%), had scores similar to those of fresh amaranth. Scores for the products prepared with dried fenugreek and shepu,although low, were not statistically significant. Microwave drying was highly suitable for greens such as amaranth; moderately suitable for shepu and fenugreek and less suitable for coriander and mint.     

脱脂和重组对面团流变学特性的影响

选用3个筋力不同的小麦品种(系)为材料,采用脱脂面粉、重组面粉和原面粉相比较的方法,研究了小麦脂类对面粉主要基础品质指标、面团拉伸和粘度特性的影响。结果表明:(1)脱脂后面粉沉淀值、降落值下降,面粉白度提高;(2)脱脂后鲁麦14和01-35的面团最大拉伸阻力、拉伸面积和最大拉伸比变大,延伸度变小,但PH3259表现为相反的趋势;(3)与原面粉相比,脱脂后面团粘度变小,附着功减少,粘聚性下降;(4)重组面粉与原面粉面团流变学特性无明显差异。