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本实验研究了葡聚糖水溶液的流变性能,选取了五种不同分子量的葡聚糖,分别考查了分子量、溶液浓度、溶液温度等因素对葡聚糖水溶液流变性的影响。结果显示,多数葡聚糖水溶液表现出牛顿流体的特性,而当葡聚糖分子量为531000,溶液浓度为30%时,溶液则表现出假塑性流体的性质,黏度随着剪切速率的提高而降低。当葡聚糖浓度较低时(≤1%),水溶液均表现出一种特殊的流变性,即黏度随着剪切速率增加先降低后升高,本研究对出现这一现象的原因进行了分析。 相似文献
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研究了凉粉草胶在不同质量浓度、温度、pH、盐的种类及盐浓度和不同蔗糖浓度下的流体行为以及固定剪切速率下的表观粘度随不同条件的变化情况。结果表明,凉粉草胶溶液在不同的条件下呈牛顿流体或假塑性流体行为,在剪切速率52.8s-1下,10 g/dL凉粉草胶溶液的表观粘度随胶质量分数(1~20 g/dL)的增加而递增,随温度(25~70℃)的升高而递减,随pH(5~12)的变化则不具有单调性,随NaCl(0~3.0 g/dL)的添加而递减,随CaCl2(0~3.0 g/dL)的添加则先减小后增大,随蔗糖(10~50 g/dL)的添加则递增。 相似文献
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《Food Science & Nutrition》2018,6(6):1741-1750
The purpose of this study was to concentrate the polyphenolic compounds in pistachio hull extract as a rich source of natural antioxidants using the membrane process and the reduction of membrane fouling during the process. After the optimization of the membrane performance includes chamber pressure and stirring rate by monitoring flux and membrane fouling, pectinase and tannase enzymes were compared in order to reduce fouling. Pectinase showed a better potential in decreasing membranous fouling. Enzyme concentration was optimized, and treatment with 17.4 (U) was selected. The permeate obtained from optimized membrane condition and enzyme level treatment was enriched in total phenol (120.31 ± 0.35 mgGAE/g) and flavonoid (34.54 ± 0.09 mgCE/g), while the amount of anthocyanin was not remarkable. 相似文献
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Amir Pouya Ghandahari Yazdi Mohsen Barzegar Mohammad Ali Sahari Hassan Ahmadi Gavlighi 《Food Science & Nutrition》2019,7(1):356-366
Phenolic compounds form an essential part of the human diet because of their functional properties. In this study, the extraction conditions of phenolic compounds from pistachio green hull were optimized by enzymatic method (using pectinase, cellulase, and tannase enzymes). For this purpose, the effective factors including the solid to solvent ratio, enzyme concentration, particles size, and extraction time were optimized. Also, the effect of enzymatic extraction on the antioxidant activity of the extracts were investigated using three different methods (DPPH˙, ABTS˙+, and FRAP). The profile of phenolic compounds was determined using HPLC/DAD. The results showed that all the studied enzymes were significantly effective in increasing the extraction efficiency. The combination of cellulase, pectinase, and tannase enzymes under their optimal conditions increased the extraction yield up to 112% in comparison with the solvent extraction method. The results of three antioxidant tests showed that the antioxidant properties of the enzymatic extracted compounds increased significantly compared to the control sample (compounds extracted by the solvent method). The DPPH˙ test results indicated that the antioxidant property of the enzymatic extracted compounds was 71% more than the control extract. The different enzymes changed the phenolic compounds’ profile so that the pectinase and cellulase enzymes increased the amount of phloroglucinol (more than three times) and decreased the amount of gallic acid (more than 4.5 times) in comparison. In addition, tannase and its combination with other enzymes increased the gallic acid content by 2.6‐fold and 4.6‐fold compared to the control sample, respectively. 相似文献
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Seyede Saba Lashgari Zohre Noorolahi Mohamad Ali Sahari Hassan Ahmadi Gavlighi 《Food Science & Nutrition》2020,8(6):2920-2928
The purpose of this study was to evaluate the effectiveness of pistachio hull extract (PHE) as an antioxidant and antimicrobial agent for preservation of dry fermented sausages during fermentation and storage period. Sausages were prepared using starter culture (Biobak K) and treated with three levels of PHE (500, 750 and 1,000 ppm). The results showed that PHE at concentrations of 500 ppm and 750 ppm decreased significantly (p < .05) the TBARS content of the sausage samples compared to control (without PHE). Moreover, PHE increased L* and a* value of samples during fermentation period but did not affect the color of samples during storage period. The PHE was also able to improve the chewiness and gumminess of the fermented sausage. Evaluation of microbial properties (total viable count, yeast and molds, lactic acid bacteria, staphylococci and Enterobacteriaceae) also showed that antimicrobial activity of PHE in fermented sausage. 相似文献
6.
商业橘皮果胶与大豆果胶流变性质的比较 总被引：1，自引：0，他引：1
通过流变学方法对商业橘皮果胶及大豆果胶溶液黏度及凝胶过程进行分析。结果表明：相同条件下,商业橘皮果胶的黏度高于大豆果胶;在形成凝胶过程中,商业橘皮果胶凝胶体系储能模量要远高于大豆果胶。果胶质量浓度为2 g/100 mL、蔗糖添加量为55、60 g/100 mL,葡萄糖酸内酯（D-glucono-δ-lactone,GDL）添加量为3、4 g/100 mL的商业橘皮果胶与相同条件下的大豆果胶储能模量差异不大;通过加入蔗糖及GDL或提高大豆果胶质量浓度,可明显提高大豆果胶凝胶体系的储能模量,增加大豆果胶的凝胶强度。 相似文献
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白玉皮壳的类型可分为石皮壳、色皮壳和糖皮壳。对新疆、青海和俄罗斯三地白玉皮壳特征进行了观察和分析,发现三地白玉皮壳在成因、颜色、形状、厚度、成分等方面各有不同。新疆白玉仔料常见色皮壳,其类型有单色、双色、多色等。青海白玉常见石皮壳。俄罗斯白玉山料亦多见石皮壳,石皮壳以白皮料（石灰皮料）和黑皮料为主,其仔料和山流水料中有少量色皮壳,常为褐色夹杂黑色。三地白玉均有糖皮壳,具一定差异。这些特征有助于区分白玉原料和部分成品的产地、判别白玉原料内部玉质质量、了解皮壳的成因和识别天然皮壳与人工染色皮壳。 相似文献
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白玉皮壳的类型可分为石皮壳、色皮壳和糖皮壳。对新疆、青海和俄罗斯三地白玉皮壳特征进行了观察和分析,发现三地白玉皮壳在成因、颜色、形状、厚度、成分等方面各有不同。新疆白玉仔料常见色皮壳,其类型有单色、双色、多色等。青海白玉常见石皮壳。俄罗斯白玉山料亦多见石皮壳,石皮壳以白皮料（石灰皮料）和黑皮料为主,其仔料和山流水料中有少量色皮壳,常为褐色夹杂黑色。三地白玉均有糖皮壳,具一定差异。这些特征有助于区分白玉原料和部分成品的产地、判别白玉原料内部玉质质量、了解皮壳的成因和识别天然皮壳与人工染色皮壳。 相似文献
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通过发酵一株野油菜黄单胞菌得到黄原胶,进而测定该黄原胶在不同质量浓度、pH值、氯化钠质量浓度、温度下黏度变化,分析黄原胶流变特性、丙酮酸质量分数和黏均分子质量。结果表明：本实验菌株的黄原胶产量达到28.4 g/L,黄原胶黏度在质量浓度高于4.0 g/L时迅速升高,黄原胶黏度在pH 3.0～10.0之间稳定。氯化钠质量浓度由10 g/L增加到70 g/L时,使1.0 g/L黄原胶黏度提高20%,而温度高于35 ℃时使1.0 g/L黄原胶黏度降低。黄原胶的丙酮酸质量分数达到6.35%,黏均分子质量为5.7×106 D。1.0 g/L黄原胶的稠度系数和流体指数分别为26.94和0.765 5,5.0 g/L黄原胶的稠度系数和流体指数分别为489.65和0.328 1。研究表明该株野油菜黄单胞菌具有较大的潜在应用价值。 相似文献
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ABSTRACT: Natrolite was used to explore a physical and safe method to decontaminate aflatoxin-containing pistachio lots. Pistachio nuts with low, medium, and high levels of aflatoxin were subjected to a washing process with a slurry of 5% natrolite. Using thin-layer chromatography and scanning, the aflatoxin contents of the samples were measured. Aflatoxins B1 and B2 were found in pistachio nuts. The majority of total aflatoxins was aflatoxin B1 Natrolite treatment resulted in a 38% to 100% reduction in aflatoxin B1 , depending on the initial aflatoxin level. Although natrolite was demonstrated to be an effective candidate to reduce aflatoxin B1 , its efficacy against aflatoxin B2 was limited. 相似文献
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Sonia Asadi Mehran Aalami Shahram Shoeibi Mehdi Kashaninejad Mohammad Ghorbani Mostafa Delavar 《Food Science & Nutrition》2020,8(6):2875-2881
Drying and roasting are conventional processes in the nut industry. However, roasting as an important procedure in nuts manufacturing may cause some physicochemical changes in nuts. Acrylamide is one of these chemical compounds that is formed due to the roasting process. Acrylamide is known as a neurotoxicant, carcinogen, and reproductive toxicant. In this study, raw and salted pistachios were roasted under three conditions including hot‐air, infrared (IR), and microwave methods. Then, 80 pistachio kernels were analyzed by ultra‐high‐performance liquid chromatography. The results showed that all samples contained different ranges of acrylamide between 57 ± 0.86 and 851 ± 2.8 μg/kg. Besides, raw pistachios and sun‐dried pistachios also contained acrylamide, with the amount of 57 ± 0.86 and 93 ± 1.07 μg/kg, respectively. The highest acrylamide amount was found in raw pistachio (unsalted) roasted by IR method, while lower acrylamide amount observed in the microwave method. The amount of acrylamide in salted and roasted pistachios was less than just roasted pistachios under the same conditions. Finally, in all the treatments, increasing temperature, time, voltage, and power lead to an increase in acrylamide levels. The results showed that acrylamide in the roasted pistachios may cause health problems. This study presents a novel investigation in the effects of roasting conditions (temperature, power, voltage, and time) on acrylamide content in pistachios. 相似文献
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Maria G. Bellomo Biagio Fallico Giuseppe Muratore 《International Journal of Food Science & Technology》2009,44(12):2358-2364
This work tested the stability of pigments (chlorophyll [chl] a and chlorophyll [chl] b, and lutein] and oil in pistachio kernels stored up to 14 months at three different temperatures: 10, 25 and 37 °C. The samples were hermetically packaged using two films (nylon and ethylene vinyl alcohol) with and without oxygen scavengers. For each temperature, reference samples were packaged in open bags. For both the oil and pigments, no differences were observed during storage, irrespective of packaging or oxygen scavengers. After 14 months, the oil showed very few changes: a slight increase in acidity and peroxide value (PV) irrespective of storage temperature; the spectrophotometric indices K232 and K268 remained the same. As for pigment stability, the lowest concentrations were observed at 37 °C with a degradation of about 62% for chl a, 44% for chl b and 57.5% for lutein. At 10 and 25 °C, the samples showed slight differences, the pigments degradations were about 46% for chl a, 33% for chl b and 37% for lutein. The degradation rate constants for the three pigments fitted a pseudo‐zero‐order kinetic in which Ea was 11.7 kJ mol?1, 12.1 kJ mol?1 and 18.2 kJ mol?1 for chl a, chl b and lutein respectively. 相似文献
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目的 对开心果中的过敏蛋白进行分离纯化, 了解开心果过敏蛋白的初级结构和致敏性。方法 将不同加工处理的开心果用二氯甲烷、TBS缓冲液进行过敏蛋白的提取分离, 采用硫酸铵分级沉淀来初步提纯过敏蛋白, 再通过透析、离子交换柱层析手段对开心果的致敏蛋白进一步纯化, 最后通过考马斯亮蓝测蛋白含量, 用紫外分光光度计波峰表征, 确定开心果致敏蛋白质种类, 通过SDS-PAGE电泳分析和WB免疫印迹实验验证开心果分离蛋白的致敏性。结果 不同比例的有机溶剂提取开心果蛋白的分离效果不同, 原味开心果1:3的得率最高达到49.49%; 不同饱和度的硫酸铵沉淀蛋白质不同, 浓度越小, 析出蛋白质种类越多; 经离子交换层析柱分离纯化之后, 蛋白质的种类组分稳定, 结合之外扫描图谱分析所测物质的结构中含有双键或三键, 属于复合蛋白质的结构。结论 开心果过敏原属于蛋白复合结构, 主要以双键和三键的形式存在, 热处理和盐焗加工会降低开心果过敏原的致敏性。 相似文献
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Juan J. Polari Lu Zhang Louise Ferguson Niels O. Maness Selina C. Wang 《Journal of food science》2019,84(7):1937-1942
Pistachio is an economically important nut crop in California. Since temperature variations among geographical locations can influence biochemical processes during fruit development, it is of great relevance to understand the impact of growing area over the components that define the nutritional and sensory characteristics of pistachio nuts. Changes in moisture, fat content, fatty acid composition and volatile terpenes were studied during kernel development for “Kerman” and “Golden Hills” varieties in two different California Central Valley microclimates, Lost Hills and Parlier. Moisture content decreased from July to September for both cultivars at both locations. Kerman had a higher moisture content at both locations compared with Golden Hills. Harvest time affected fat content only for Kerman, where the values increased drastically from 21‐July to 4‐Aug, then remained constant. Golden Hills’ fat content remained constant during the period of the study. The main fatty acid in pistachio oil is oleic acid (46% to 59%), followed by linoleic acid (26% to 36%) and palmitic acid (11% to 16%). C16:0, C16:1, C18:2, and C18:3 decreased with harvest time, while C18:1 increased. α‐Pinene was the most concentrated volatile among the cultivars and locations. It decreased with harvest time for both cultivars at both locations, ranging from 105 to 2464 mg/kg. At harvest, Golden Hills and Kerman at Parlier both had higher concentrations of α‐pinene than the two cultivars at Lost Hills. Our results demonstrate that microclimate affects biosynthesis of fatty acids and terpenes in pistachio kernels, the main compounds responsible for pistachio nutritional and sensory characteristics. 相似文献
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为了研究碰撞位姿对开心果碰撞声离散性的影响,在除碰撞位姿不作控制、其余条件均相同的情况下,分别对单个开闭口开心果进行100次重复碰撞试验,对两组碰撞声信号的频谱离散性和统计参数的离散性进行分析研究。频谱的离散性以样本信号频谱向量与其平均向量间的夹角均值和夹角变异系数作为度量;统计参数的离散性采用信号的能量、熵、过零率等参量,以其变异系数作为度量。试验结果显示:1单颗开口开心果重复碰撞声信号的频谱向量与其平均向量间夹角均值为30.94°,夹角变异系数为16.56%;能量、熵、过零率参数的变异系数分别为38.33%,2.30%,20.00%,均值分别为11.20,4.39,63.43;2单颗闭口开心果重复碰撞声信号的频谱向量与其平均向量间夹角均值为20.52°,夹角变异系数为25.11%;能量、熵、过零率参数的变异系数分别为18.36%,2.27%,13.08%,均值分别为6.08,4.28,62.94。结果表明:1不作控制的碰撞位姿对单颗开闭口开心果重复碰撞产生的声信号均有影响,会发生离散;2在由碰撞位姿导致的碰撞声的离散程度上,开口离散程度比闭口的高;3除碰撞位姿不作控制、其余试验条件均相同的情况下,虽然单颗开闭口开心果碰撞声的频谱和统计参数都会发生离散,但各参数均在其均值附近有限的范围内变动,所以,通过提取均值差异大且变异系数小的特征参数可以实现开口果和闭口果的有效分类。 相似文献