米糟制备大米蛋白研究

以米糟为原料对四种制备大米蛋白不同方法,即碱蛋白酶两步法、水溶液洗涤法、淀粉酶除杂法和非淀粉酶除杂法进行比较;研究结果发现,后三种方法在制备大米蛋白时得率(>85%)和纯度(>80%)明显高于第一种方法得率(约69.2%)和纯度(约70%)。     

挤压协同淀粉酶法制备高粱蛋白及其组成分析

以高粱为原料,通过挤压协同淀粉酶法提取高粱蛋白,研究物料水分、挤压温度和淀粉酶活力这3个因素对高粱蛋白提取率和纯度的影响,发现蛋白质提取率和纯度随着物料水分和挤压温度的升高表现出先上升后降低的趋势,在物料水分为19%、挤压温度为150℃有最大值;蛋白质提取率和纯度随着淀粉酶活力的增加而增加,当淀粉酶活力大于2.0 U/g淀粉时,提取率与纯度的变化趋势趋于平缓。在此基础上以蛋白质纯度为指标设计正交实验,得到挤压协同淀粉酶法制备高粱蛋白的最优工艺:挤压温度165℃,物料水分19%,淀粉酶活力2.0 U/g淀粉。此条件下高粱蛋白提取率83.20%,纯度79.23%。氨基酸分析和营养评价显示,本实验制备的高粱蛋白具有良好的氨基酸平衡和较高的氨基酸利用率。SDS-PAGE凝胶电泳显示,此法提取的高粱蛋白包含醇溶蛋白和谷蛋白。     

酶法制取大米麦芽糊精和浓缩蛋白

以大米为原料,采用高温α-淀粉酶酶解淀粉制取麦芽糊精,然后分离提取浓缩蛋白。结果表明,使用高温α-淀粉酶3mL、固液比1∶4、酶解温度95℃、酶解时间1h,其DE值为8.44,大米蛋白纯度达82.41%,提取率达94.69%。麦芽糊精的理论平均分子量为2150.68Da;蛋白质氨基酸组成分析表明,其氨基酸组成没有明显变化,证实酶法制取大米麦芽糊精和浓缩蛋白是一种可行的方法。     

提高大米蛋白提取率的工艺研究

考察了不同提取方法对大米蛋白提取率的影响,对不同提取方法进行了比较。结果表明:高压均质处理可提高蛋白提取率;淀粉酶酶解可提高大米蛋白提取率。同时复合法提取与单一法提取相比,提取率明显提高。采用淀粉酶酶解、碱提、蛋白酶酶解工艺,提取率可达81.25%。     

以大米为原料联产大米蛋白和酒精的生产工艺研究

早籼米为原料,碱法提取大米蛋白并把提取蛋白质后的物料发酵制备酒精.研究了大米粉粒度、碱液浓度、料液比、提取时间以及提取温度等因素对大米蛋白纯度和提取率的影响,对比了提取部分蛋白质后的物料和大米粉发酵制备酒精的效果.实验确定了提取大米蛋白的较佳工艺条件为:大米粉粒度为过0.8 mm筛、碱液浓度0.05 moL/L、料液比1:4、提取时间3 h、提取温度30℃.此条件下提取得到的大米蛋白纯度为94.5%,提取率为52.0%.大米提取部分蛋白质后对发酵制备酒精的影响不大:最主要是发酵时间延长.     

大米蛋白提取工艺研究进展

综述了国内外大米蛋白提取工艺,介绍了制备大米蛋白的常用方法：溶剂提取法、蛋白酶提取法、物理分离法、淀粉酶法、复合酶法,以及这些方法的优点和缺陷。溶剂法中非碱液提取法存在生产成本高、食品安全隐患等问题;碱法提取则耗用大量碱液,存在环境保护问题;蛋白酶法提取亦存在提取率低、成本高的问题;物理分离法目前我国还不具备相当成熟的技术实力。     

碱法提取籼碎米中大米蛋白工艺的研究

本文以籼碎米为原料,采用传统碱法提取制备大米蛋白,研究大米蛋白提取的最佳工艺.研究结果得出:从籼碎米中制备大米蛋白的最佳工艺条件为:NaOH浓度为0.09 mol/L,料液比为1:6,提取温度为25℃,提取时间为4 h,大米蛋白的提取率为77.3%,蛋白质纯度为80.5%.     

碱法与酶法提取大米蛋白工艺及功能特性比较研究

对大米蛋白的提取工艺和功能特性进行了比较研究。大米蛋白的提取采用碱法和酶法分别提取。研究结果衣明．碱法提取大米蛋白的工艺条件为在室温下，用0．1mol／L的NaOH以1：7的同液比提取4h。提取得到的大米蛋白纯度达到90％，提取率55％。酶法提取大米蛋白的工艺条件为温度50℃，pH为8，E／S为5％，液固比为3：1，酶解时间为4h。提取的大米蛋白提取率为40％，蛋白质纯度为45％。碱法提取的大米蛋白持水性、吸油性和起泡性优于酶法提取的大米蛋白，而酶法提取的大米蛋白的溶解性、乳化稳定性和泡沫稳定性优于碱法提取的大米蛋白。两种方法提取得到的产品乳化能力相当。     

提取方法对脱脂薏米蛋白功能特性的影响

以脱脂薏米为研究对象,采用碱法和酶法(蛋白酶和淀粉酶)提取薏米蛋白,并比较3种提取方法对薏米蛋白的功能特性(溶解性、持水性、持油性、乳化性及乳化稳定性、起泡性及起泡稳定性)的影响。结果表明,采用碱法、蛋白酶法和淀粉酶法提取的薏米蛋白的纯度分别为71.05%、86.66%、38.13%。在pH 9.0时,蛋白酶提蛋白的溶解性最大,为86.04%。温度为40℃时,碱法提蛋白的溶解性最大,为79.5%。蛋白酶法提取的薏米蛋白的乳化性、持水性优于碱法和淀粉酶提取的。     

大米蛋白制备研究进展

大米蛋白是一种优质的谷物蛋白,是目前稻米深加工的研究热点。介绍了制备大米蛋白的常用方法如溶剂提取、酶法提取、碱法提取、物理分离和复合提取法,并且探讨了各自的特点。     

Effect of ozone treatment on physicochemical properties of waxy rice flour and waxy rice starch

The effect of ozone treatment on physicochemical properties of waxy rice flour and waxy rice starch was investigated. Results showed that ozone treatment increased the pasting viscosity of waxy rice flour. Compared with untreated waxy rice flour, the peak viscosities of waxy rice flour for 0.5, 1 and 2 h of ozone treatments were increased by 27.4%, 32.8% and 45.5%, respectively. The alpha‐amylase in waxy rice flour was inactivated during the treatment. The gelatinisation temperature and enthalpy of waxy rice flour were kept unchanged after the treatment. For waxy rice starch, pasting viscosity, swelling power and molecular weight were increased after 0.5 h of treatment, but decreased as treatment time extended. The ozone treatment decreased gelatinisation temperature and enthalpy of waxy rice starch.     

The incorporation of sweet potato application in the preparation of a rice beverage

Summary To increase the industrial applications of sweet potato, a rice beverage was prepared by adding barley sprouts, sweet potato, or a mixture of barley sprouts and sweet potato (1:1). Amylases from barley sprouts and sweet potatoes had a similar hydrolysis pattern to β‐amylase. Heat stability of this enzyme in sweet potato was higher than that in barley. Reducing sugar content in the mixture of barley sprouts and sweet potato was higher than in either barley sprouts or sweet potato alone. After the preparation of the rice beverage, the maltose content of the mixture with barley sprouts, either barley sprouts and sweet potato, or sweet potato was 37.2, 44.1 and 40.3 mg mL^?1 after 6 h, respectively. The amylase activity in the mixture with barley sprouts and sweet potato decreased more than that of the mixture with only sweet potato. The use of sweet potato resulted in an increase of sweetness, flavour and improved preference in rice beverage.     

Interfacial and emulsifying behaviour of rice protein concentrate

Interfacial and emulsifying properties of rice protein concentrate (RPC) have been studied in order to evaluate its potential application to stabilize O–W emulsions. The interfacial behaviour of adsorbed proteins films constituted with RPC has been studied at the air–water and oil–water interfaces at two pH values (2 and 8). The type and the amount of soluble proteins have been determined in aqueous dispersions and results put forward the presence of most frequent rice protein profile and a significant degree of protein denaturation with a very low solubility. Air–water and oil–water interfacial properties have been determined as a function of time, concentration and pH: air–water by surface pressure under compression–expansion cycles and oil–water by interfacial tension. Interfacial rheology has been studied under dilatational deformations, either at the initial step of film formation or once the interfacial tension was at equilibrium (the film was completely formed). RPC-stabilised O–W emulsions has been also analysed by Droplet Size Distribution (DSD) measurements and interfacial protein concentration. Both interfacial and bulk emulsion properties reveal that RPC showed an enhanced potential as emulsifier at low pH. Globally; results indicate clearly important differences in the structural characteristics of rice protein films between pH 2 and 8 that impact on emulsifying properties.     

Relating raw rice colour and composition to cooked rice colour

BACKGROUND: The whiter the rice, the more it is preferred by consumers and the more value it has in the market place. The first objective of this study was to determine the interrelationships of raw colour, cooked colour, amylose content and protein content in rice. The second objective was to assess whether or not the colour of cooked rice can be predicted from raw rice colour in conjunction with amylose and protein contents. RESULTS: Protein and amylose contents were not significantly correlated with the colour measurements for raw rice. Protein and amylose showed moderate, significant associations with L* and a* and a*, b* and C* respectively for cooked rice. Only the colour variable a* of cooked rice could be predicted using protein, amylose and raw rice colour with high enough precision to be useful, and this was only for modelling using samples cooked in the same manner (rice cooker). Cooking method (rice cooker versus excess water) affected the colour of cooked rice. CONCLUSION: Being able to predict a* in cooked rice is likely of limited value. Only the model that used samples where postharvest handling conditions were controlled (US‐grown rice) was able to predict C*, a more useful measure, and then with only moderate ability. L*, a measure of brightness/whiteness, was not predicted well by any of the models. Copyright © 2011 Society of Chemical Industry     

糙米酵素发酵工艺的中试研究

为进一步优化糙米酵素的中试发酵工艺参数,以淀粉酶活力为测定指标,通过正交试验确定糙米酵素的中试发酵条件。结果表明,每100 kg原料,酵母接种量4%,发酵时间6h,发酵温度30℃。该条件下糙米酵素的淀粉酶活力稳定,平均值为442.2U/g。产品呈乳白色,气味醇香,酸甜适口,状态均匀。验证试验结果表明该工艺条件稳定可行,重复性好,为糙米酵素的工业化生产奠定了基础。     

对广东省三种籼稻谷的品质分析

本文对广东省内产的3种籼稻谷（中二软占、特籼占25、珍桂矮1号）质量进行品质分析（出糙率、不完善粒、整精米率、垩白粒率、垩白度、粒型、胶稠度、直链淀粉含量、食味品质）。结果表明：3种籼稻谷质量存在明显差异。     

稻米胚及米胚油的品质分析

从原料米糠中分离出纯稻米胚和纯米糠,利用溶剂浸出法分别提取其中油脂并进行品质分析对比,以研究稻米胚及米胚油的营养品质。结果表明:稻米胚粗脂肪含量27.06%,粗蛋白含量19.50%,粗纤维含量4.88%,比米糠粗脂肪、粗蛋白含量明显提高,粗纤维含量降低;米胚油的酸值(KOH)、过氧化值、维生素E含量、谷维素含量、植物甾醇含量分别为21.7 mg/g、6.1 mmol/kg、43.18 mg/100 g、0.47%、3.07%,与米糠油相比,米胚油的酸值(KOH)降低了23.8 mg/g,过氧化值降低了1.7 mmol/kg,维生素E含量提高了17.18 mg/100 g,植物甾醇含量相差不大,谷维素含量降低0.93个百分点。米胚油在酸值和维生素E含量方面较米糠油具有明显优势,新鲜稻米胚既可以直接作为营养丰富的产品,也是优质食用油的原料。     

Underlying reasons for waxy rice flours having different pasting properties

The underlying reasons for three waxy rice varieties, Yang-fu-nuo (Y), Su-yu-nuo (S), and Guang-ling-xiang-nuo (G), having different flour pasting properties were examined. The pasting properties of the isolated waxy rice starches did not correlate with those of the corresponding waxy rice flours. Examining the pasting properties of the flours in 0.5 mM AgNO₃ solution, treated with dithiothreitol and protease, suggested that rice protein and amylase activity were the main causes of the pasting property differences among the rice starches and flours. Starch isolated from Y flour had a larger proportion of A and B₁ chains, longer average chain length and longer exterior chain length, which explained its higher gelatinisation temperature, higher pasting consistency, greater extent of retrogradation, and the firm texture of cooked Y rice.