THE EFFECT OF FERMENTATION ON CASSAVA STARCH MICROSTRUCTURE

The effect of glucose syrup addition on sour cassava starch fermentation was studied on cassava starch from three locations in Santa Catarina State (Brazil), following four treatments: traditional, 0.10, 0.25 and 0.50% of glucose syrup added to total cassava suspension volume. A glucose syrup concentration of 0.50% contributed to doubling fermentation yield. The objective of this work was to observe the effect of the cassava starch fermentation process on starch granule microstructure, as compared with industrial processing. Micrography was performed using a scanning electron microscope, at 2000× magnification. Fermentations with 0.50% glucose syrup presented the greatest effects on starch granule microstructure.     

TRIAL METHOD FOR MEASURING THE EFFECT OF LIPIDS ON THE RHEOLOGICAL PROPERTIES OF STARCH PASTE DURING THE GELATION PROCESS

An attempt was made to measure the effect of lipid components on the viscosity and thixotropy of wheat starch paste in a short aging time after gelatinization. Viscometry was used to follow periodically the changes in apparent viscosity (at 76.8 s⁻¹) of the mixed paste of wheat starch and one of a series of lipids in a cone-plate viscometer for 210 min after gelatinization, i.e. a procedure of eight cycles of measurement with a sample. Each cycle of the measurement consisted of viscometry for 3 min and a rest period for 27 min at 30°C. The apparent viscosity of all the samples decreased greatly during the 3 min measurement due to thixotropic breakdown of the macroscopic structure in the samples. The results suggest that the presence of a small amount of free fatty acid and monoglyceride may play a role in reducing starch paste gelation.     

复合保鲜剂对菊花脑保鲜效果的影响

通过正交试验研究了以6-苄基腺嘌呤、赤霉素、水杨酸和欧威消毒剂组成的复合保鲜剂对菊花脑的保鲜效果.结果表明,复合保鲜剂处理的菊花脑,在10℃下贮藏12 d,以叶绿素含量作为评价指标.四因素6-苄基腺嘌呤、赤霉素、水杨酸和欧威保鲜消毒剂在减缓菊花脑黄化方面的作用大小依次为6-苄基腺嘌呤、水扬酸、欧威消毒剂和赤霉素;四因素的最佳复合组合是10mg/L6-苄基腺嘌呤 20mg/L赤霉素 14mg/L水杨酸 100mg/L欧威消毒剂,最佳组合可有效减缓叶绿素、蛋白质和可溶性固形物的损失,抑制菊花脑黄化、失重和纤维化.减少超氧阴离子和丙二醛含量,从而延缓了采后菊花脑的衰老.     

小麦淀粉磷酸酯取代度的测定

本实验采用总磷减去游离磷的方法求出结合磷,并对总磷及游离磷的测定条件进行摸索,从而得出一个新的方法,可以简捷快速、可靠的测定淀粉磷酸酯的取代度,为指导实验室研究工作及保证生产中产品质量稳定提供依据。     

水溶性大豆多糖对淀粉糊化特性的影响

利用快速粘度分析法(RVA)和差方扫描量热法(DSC)研究三种水溶性大豆多糖SSPS、SSPS-G1、SSPS-G2对淀粉糊化特性的影响.结果表明:它们均能显著影响淀粉的糊化特性,但作用效果不同,SSPS-G1与SSPS-G2对淀粉糊化特性的影响更显著.     

EFFECT OF SUGAR AND GUMS ON THE PASTING PROPERTIES OF CASSAVA STARCH

Pasting properties of cassava starch solutions were prepared with different types of sugars (glucose, sucrose and fructose) at different levels as 10.71, 19.35, 32.43% and gums (gum acacia, guar gum and gum tragacanth) at 0.1, 0.2, 0.3, 0.4% levels, respectively, were analyzed using the Rapid Visco Analyzer. The pasting temperature increased with increase in the sugar concentration in cassava starch–water system and the maximum 78.27C at 32.43% sucrose solution. The peak viscosity (PV) and breakdown viscosity (BD) decreased with increase in the sugar concentration. Hot paste viscosity and cold paste viscosity decreased progressively with increase in sugar concentration in fructose and glucose solution. The PV and BD increased with increase in guar gum concentration and was maximum 5,704 and 3,773 mPa·s at 0.4% concentration, respectively.

PRACTICAL APPLICATIONS

Cassava starch performs most of the functions where maize, rice and wheat starch are currently used. In food industry, cassava starch is used in extruded snacks for improved expansion, as a thickener in foods, in processed baby foods as a filler material and bonding agent in biscuit and confectionary, textile, pharmaceutical, paper and cosmetic industries. Cassava starch can be converted to maltotriose, maltose, and glucose as well as to other modified sugars and organic acids. Starch from cassava can be used to make gelatin capsules. Starches and gums are often used together in food systems to provide texture, control moisture, water mobility, improve overall product quality and stability, reduce cost and facilitate processing. Cassava starch, due to its high swelling power, is reported to yield better quality instant noodles.     

用紫外分光光度法对棉籽油中棉酚定量测定的研究

棉酚是一种毒性较强的化合物,且分布较广.本文研究了用60%的乙醇萃取棉籽油中的游离棉酚,然后用UV—240分光光度计在233nm波长下进行测定,所得结果相对误差小于6.25%.此法灵敏度高,重现性好,操作简便,理论检测下限为5ppm.     

富马酸酯类防腐剂改性方法研究现状

富马酸酯类具有良好的抗茵活性,广泛用做食品防腐剂.近年来人们通过对富马酸酯类进行结构改造,合成具有防腐及其它综合性能的新型食品添加荆.介绍富马酸单酯、溴代富马酸二甲酯、反丁烯二酸蔗糖甲酯等富马酸酯衍生物的改性方法及改性效果的研究现状.     

DETERMINATION OF THE PROTEIN CONTENT IN RICE BY THE DIGITAL CHROMATIC METHOD

ABSTRACT

The feasibility of using digital chroma measurements to determine the protein content in rice was investigated using red, green and blue (RGB) chroma values to reflect color change. The protein content of rice samples ranged from 5 g/100 g to 13 g/100 g. There was a significant negative linear correlation (r < −0.98) between the protein content in rice and the chroma values of relevant protein solutions treated with biuret reagent. Of all the tricolor values, the G value was the optimal parameter to reflect the chroma difference of the protein solutions. It had a higher correlation coefficient (r < −0.99) and was more sensitive to subtle differences in protein content than R or B values. With a similar structure and the same reaction conditions, rice samples with known protein content were found to be more accurate calibrating substances. The results determined by the digital chromatic method are not significantly different from that of the Kjeldahl method. With the advantages of high precision, easy operation and high efficiency, the method is suitable for applications in quality evaluation and supervising practice in the field of rice circulation.

PRACTICAL APPLICATIONS

A new method to determine the protein content of rice was studied by combining digital image analysis technology and a traditional chemical approach. The study forms a part of the technology foundation to develop quality evaluation systems for rice.

     

紫外分光光度法测定植物黄酮含量的方法

综述了紫外分光光度法测定植物中黄酮含量的方法。重点介绍了单波长法、差示法、双波长法、三波长法、导数法等紫外分光光度法测定黄酮类化合物含量的原理及分析特性。     

THE EFFECT OF PROCESSING METHOD ON THE CHARACTERISTICS OF CARROT JUICE

ABSTRACT

The production of carrot juice using different technologies is the main subject of this investigation. Although the production and preservation of the carrot juice technology have not been improved and are not prevalent, an intensive study has been carried out on this subject recently. In this study, the effects on the yield and quality of carrot juice produced with and without total enzymatic liquefaction (Pectinex Ultra SP‐L, Novo Nordisk Ferment, Dittingen, Switzerland) as well as lactofermentation or citric acid addition have been investigated. Generally, enzymatic liquefaction of mash increased the juice yield (89.32 ± 1.17 and 90.43 ± 0.47% for lactofermented and citric‐acid‐added samples, respectively), while the control sample juice yield was found to be 59.90 ± 0.81%. Lactofermented and acid‐added samples demonstrated lower pH value. In enzyme‐treated samples, the total acidity increments were also determined. Accordingly, galacturonic acid formed after enzymatic breakdown of pectin in the raw material increased the total acidity of the samples. Magnesium contents of lactofermented juices were found to be low because lactic acid bacteria require magnesium for their growth. β‐Carotene contents have been found to be higher in both lactofermented and in nonenzyme‐treated samples.

PRACTICAL APPLICATIONS

This article describes the effects of different processing methods on the characteristics of carrot juice. It is difficult to preserve vegetable juices such as carrot juice because of their low acidity. The acidity of carrot juice (pH ～6.2) can be adjusted by the addition of citric acid or the lactofermentation method to pH 4.5. With these processes carrot juice can be preserved by pasteurization as occurs for low pH fruit juices, increasing shelf life. According to the results of this study, increasing the acidity of mash with lactofermentation or citric acid addition also increases the juice yield.

     

超声强化制备低取代度黄姜醋酸酯淀粉的工艺研究

在比较未施加超声场和超声强化制备相同取代度黄姜醋酸酯淀粉条件的基础上,以黄姜醋酸酯淀粉的取代度为指标,探讨用超声强化制备低取代度醋酸酯淀粉的工艺,并用扫描电镜（SEM）对产物的表面形貌进行分析。结果表明：超声强化可以促进淀粉的酯化反应,而且制备低取代度的醋酸酯淀粉的效果更为明显。超声强化制备低取代度醋酸酯淀粉过程中,超声作用时间影响显著,其最佳工艺条件为：超声作用时间为15min,超声温度为50℃～60℃,超声波功率为96W。由SEM分析结果可知,超声辅助法对所制备的相同取代度的黄姜醋酸酯淀粉的颗粒大小和表面形貌有一定的影响。     

复合天然保鲜剂对低温酱鸭保鲜效果的研究

以低温酱鸭为原料，通过对6种天然保鲜剂进行筛选，选出4种抑菌效果较好的，进一步进行组合实验，根据抑菌率得出抑制酱鸭腐败菌的最佳组合为壳聚糖2．00％、乳酸链球菌素（Nisin）0．01％、茶多酚1．00％、桂皮2．40％。采用此最佳组合的复合天然保鲜剂对酱鸭进行保鲜实验，定期测定其微生物指标和理化指标，结果表明利用优选的组合保鲜剂保鲜，加上真空包装、低温水浴杀菌，可使酱鸭保质期冷藏达2-3个月。     

EFFECT OF KILNING ON MALT STARCH AND ON THE DEXTRIN CONTENT OF RESULTING WORTS AND BEERS

Examination of starches separated from green malt and from kilned malts of colour ranging between 3 and 23 shows that only small amounts of “new” carbohydrate linkages are formed in the starches during kilning, though the colour changes from white to buff and the amount of contaminating protein increases. Nevertheless, standard enzymic treatments show that the higher the colour value of the malt, the less susceptible it is to attack by amylases, and the larger is the content of non-fermentable, non-dialysable dextrin. Although the amount of non-dialysable dextrin rises as the colour value of the malt increases, dextrin content of the derived wort is not directly related to the enzymic activity of the malt. Thus, the non-fermentable dextrin of wort from malt of colour 3 is little higher than that of wort from green malt, despite the considerably higher diastatic power of the latter. Head retention values of draught and bottled beers from the green malt and kilned malts of colours 3, 6 and 13 show no correlation with dextrin content.