Impact of Postharvest Operations on Rice Grain Quality: A Review

Postharvest operations, such as drying, storage, and milling, have been used to ameliorate the aging of rice grains and to achieve and maintain desirable rice grain quality, and thus play a key role in determining rice commercial quality and value. This review summarizes publications from the past decade and outlines the evidence supporting attribution of grain quality changes induced by postharvest processes to changes in the physical properties and chemical composition of the rice grain (starch, protein, lipids, and antioxidants). Rice drying mainly affects rice milling quality as rice kernel fissuring that may occur during drying leads to head rice yield reduction. Rice grain aging occurring during storage is inevitable and responsible for the changes in rice appearance, milling, eating, cooking, and nutritional quality. As milling significantly changes the chemical composition of rice by removing protein‐ and lipid‐rich bran layers, milling can alter the aging process of rice and also affect rice appearance, eating, and sensory quality, but mainly affects the nutritional quality. Therefore, drying methods, storage conditions, and milling methods warrant further research to achieve and maintain the desired rice grain quality. This review may contribute to better understanding of the impacts of postharvest processes on rice grain quality, and provide insights into potential improvements in these practices for rice production and utilization in the whole rice industry.     

紫薯黑米凝固型酸乳的生产工艺研究

以紫薯和黑米为原料,对紫薯黑米凝固型酸乳的生产工艺进行研究。紫薯汁与黑米汁最佳体积比为1∶1,蔗糖添加量为7%,稳定剂选用低甲氧基果胶,紫薯黑米凝固型酸乳品质较好。通过响应面分析法确定紫薯黑米凝固型酸乳发酵最佳工艺,即为接种量为6.9%,紫薯汁和黑米汁添加量为12.7%,发酵温度为38.1℃,发酵时间为4.5 h。     

碱解玉米皮制备阿魏酸的研究

通过碱解玉米皮可释放阿魏酸.采用正交设计探讨了碱解和纯化阿魏酸的工艺,其最佳工艺为用含1%Na0H的50%乙醇溶液于85℃回流反应2h提取玉米皮(质量比110)中的阿魏酸.为防止阿魏酸氧化,在提取液中添加50 mg/100 mL的亚硫酸氢钠.将碱解液减压浓缩,用盐酸调节pH至3.0.每次用2倍体积的乙酸乙酯萃取3次,取酯相,减压挥干乙酸乙酯,用碱液溶解,再用盐酸调pH=2,所得产品为黄色油状物.检测结果表明,采用该工艺获得的阿魏酸纯度达82.69%,收率为148.92 mg/10 g玉米皮.     

Effects of phytase,cellulase and dehulling treatments on zinc in vitro solubility in faba bean (Vicia faba L.) flour and seed fractions

Simulations of gastro‐intestinal digestion was used to try to identify the nature of the complexes between antinutritional factors and zinc in faba bean fractions. In the hull fraction, the action of phytases and the simultaneous action of cellulase and phytase allowed about 7% and 35% additional zinc to be solubilised, respectively. Single enzymatic degradation of phytates from dehulled faba bean allowed solubilisation from 65% to 93% of zinc depending upon the treatment. The zinc of faba bean flour was mainly linked to phytates and the greater the degree of phytate degradation before in vitro digestion, the greater the quantity of zinc released. In dehulled faba bean zinc was almost exclusively chelated by phytates. In the hull of faba bean, the majority of zinc was chelated in complexes between phytates and fibres.     

消泡剂在造纸工业中的应用和发展趋势

分析了造纸过程泡沫产生的原因和消泡剂的消泡机理,综合介绍了常用消泡剂产品的组成、种类、性能和在制浆、抄纸、涂布等工段的使用情况,并对造纸用消泡剂的发展趋势进行了展望。     

Modification of pectin polysaccharides during ripening of postharvest banana fruit

Pectin is one of the major components of the primary cellular walls and middle lamella in plant tissues. In this study, water-soluble pectin (WSP) and acid-soluble pectin (ASP) fractions were isolated from pulp tissues of banana fruit at various ripening stages. Their monosaccharide compositions, glycosyl linkages and molecular mass distributions were evaluated. As ripening progressed, fruit firmness decreased rapidly, which was associated with the increase in the WSP content and the decrease in the ASP content. Meanwhile, the molecular mass distributions of WSP and ASP fractions exhibited a downshift tendency, indicating the disassembly of pectin polysaccharides. Moreover, galactose and galacturonic acid as the major monosaccharide compositions of pectin polysaccharides increased in WSP fraction but decreased in ASP fraction during fruit softening. GC–MS analysis further revealed that pectin polysaccharide had a 1,4-linked galactan/galacturonan backbone with different types of branching and terminal linkages in WSP and ASP fractions. During banana fruit ripening, the amount of 1,4-linked Galp residues of ASP fraction decreased significantly whereas 1,3,6-linked Galp, 1,2-linked Manp and 4-linked Araf residues disappeared, which was related to depolymerization of pectin polysaccharides. Overall, the study indicated that the modifications in polysaccharide compositions and glycosyl linkages, reduced molecular mass distributions and enhanced depolymerization of pectin fraction during banana ripening were responsible for fruit softening.     

A novel common single primer multiplex polymerase chain reaction (CSP‐M‐PCR) method for the identification of animal species in minced meat

BACKGROUND: Minced meat species adulteration is a severe problem. In this study a common single primer multiplex polymerase chain reaction (CSP‐M‐PCR) method was applied to the identification of five species (chicken, cattle, sheep, pig and horse) in minced meat products. CSP was designed as a common adapter at the 5′‐end of species‐specific reverse primers and employed in giving different length fragments from the respective meat species. RESULTS: Species‐specific DNA fragments could be identified in a single PCR reaction by mixing CSP, Chicken‐R, Cattle‐R, Sheep‐R, Pig‐R and Horse‐R primers in the ratio 1:0.01:0.01:0.01:0.01:0.10 (where ‘1’ represents 0.5 mmol L^?1). The specific DNA fragments could be efficiently amplified by CSP‐M‐PCR with > 5 µmol L^?1 species‐specific primers, except for 50 µmol L^?1 Horse‐R. A detection limit of 0.5 g kg^?1 was determined for both single species of minced meat and all species of five kinds of minced meat. CONCLUSION: The CSP‐M‐PCR method simplified the PCR reaction system and removed the inconsistent amplification efficiency from different primers. This highly sensitive, reproducible and rapid method could potentially be used as a screening or identifying assay to test for the presence of species or ingredients in minced meat and other meat products. Copyright © 2008 Society of Chemical Industry     

复合酶法优化木薯微孔淀粉的工艺及吸附性研究

为优化木薯微孔淀粉的制备工艺,提高吸附性能,采用复合酶法对木薯淀粉进行处理.借助L9(34)正交实验,研究复合酶的用量、pH值、反应温度和反应时间对微孔淀粉吸附性的影响.实验得出:与木薯淀粉对亚甲基兰溶液、食用油的吸附性能相比,微孔淀粉的吸附性能明显提高.最佳工艺条件是:酶用量2.0%,pH值5.5,温度50℃,反应时间36 h.     

喷淋淀粉混合物改善双层纸板的层间结合强度

工厂将天然淀粉液喷淋到成形的湿纸幅上以改善多层纸板的层间结合强度。文中研究了回收针叶木硫酸盐浆手抄片湿纸幅干度、淀粉液喷淋量及干燥温度对双层纸板层间结合强度的影响。淀粉喷淋到湿纸幅上可以大幅度提高湿纸板的层间结合强度。湿纸幅干度在10％-11％左右时,强度达到最大。针对高温快速干燥影响淀粉的胶凝化作用,降低纸板的层间结合强度,提出了一种高干燥速率下提高纸板层间结合强度的方法,实现淀粉逐步胶凝化,大大提高纸板层间结合强度。