超高压处理对丹阳黄酒香气成分及其感官影响的研究

采用顶空固相微萃取与气相色谱-质谱联用检测分析了超高压处理对丹阳黄酒香气成分的影响。结果表明,与未超高压处理的丹阳黄酒比较,300MPa、400MPa和500MPa条件下对样品处理20min后,丹阳黄酒中的香气成分异丁醇、异戊醇、2,3-丁二醇、苯乙醇等醇类和乙酸乙酯、丁二酸二乙酯、苯乙酸乙酯等酯类含量明显升高,乙醛含量明显减少。在3个超高压处理中,400MPa、20min处理的丹阳黄酒香气的变化最明显。感官评定结果表明,在400MPa、20min处理条件下,丹阳黄酒的口感更加鲜美、爽口、醇厚和协调。     

常压等离子体在全棉精梳府绸大生产前处理工艺研究

利用自行研制的常压低温等离子体设备,对全棉精梳府绸织物进行前处理。对比传统工艺进行毛效、白度、退浆率、断裂强度等指标测试,优选出最佳府绸等离子体处理后的前处理工艺,即坯布→等离子体处理→烧毛→水洗→氧漂→后续加工,其处理结果与传统工艺相比基本相同,其中断裂强力还有所增加。实现了节能减排、清洁生产的目的。     

改善常压渗糖白果果脯品质的工艺研究

研究了前处理、加工过程和后处理对白果果脯品质的影响。结果表明,前处理对白果果脯品质影响最大,是改善白果果脯品质的重要因素。生产优良产品的最佳工艺条件为:前处理用20%糖液高压煮沸20min,加工过程采用分梯度常压渗糖,糖液浓度从第1天的50%升到第2天的70%,后处理抛光后再进行真空包装(真空度为0.03MPa)。     

Chemical compositional characterization of eight pear cultivars grown in China

The sugar, organic acid, amino acid and fatty acid compounds of eight commercial pear cultivars were identified and quantified using high-performance liquid chromatography (HPLC) equipped with RI and UV detectors and gas-chromatography (GC) equipped with FID detector. The mineral composition was determined by inductively coupled plasma-mass spectrometry (ICP-MS). The results showed great quantitative differences in the composition of the pear cultivars. Fructose was the dominant sugar in the eight pear varieties, followed by glucose and sucrose, while malic acid was the principal organic acid. The C16:0, C18:0, C18:1, C18:2 and C18:3 fatty acids were clearly the most abundant fatty acids, and the C18 family comprised more than 70% of the total fatty acids content. Asparagine and serine were the principal amino acids. Potassium is the most abundant mineral, followed by magnesium and calcium. The results provide important information on how to make the best use of pear cultivars investigated for different uses, which is of significance for both technological research and processing practice.     

Effects of high pressure/thermal treatment on lipid oxidation in beef and chicken muscle

Lipid oxidation was studied in beef and chicken muscle after high pressure treatment (0.1–800 MPa) at different temperatures (20–70 °C) for 20 min, prior to storage at 4 °C for 7 days. Pressure treatment of beef samples at room temperature led to increases in TBARS values after 7 days storage at 4 °C; however, the increases were more marked after treatment at pressures ?400 MPa (at least fivefold) than after treatment at lower pressures (less than threefold). Similar results were found in those samples treated at 40 °C, but at 60 °C and 70 °C pressure had little additional effect on the oxidative stability of the muscle. Pressure treatments of 600 MPa and 800 MPa, at all temperatures, induced increased rates of lipid oxidation in chicken muscle, but, in general, chicken muscle was more stable than beef to pressure, and the catalytic effect of pressure was still seen at the higher temperatures of 50 °C, 60 °C and 70 °C. The addition of 1% Na₂EDTA decreased TBARS values of the beef muscle during storage and inhibited the increased rates of lipid oxidation induced by pressure. The inhibition by vitamin E (0.05% w/w) and BHT (0.02% w/w), either alone or in combination, were less marked than seen with Na₂EDTA, suggesting that transition metal ions released from insoluble complexes are of major importance in catalysing lipid oxidation in pressure-treated muscle foods.     

Effects of processing and cooking on ascorbic acid content of chickpea (Cicer arietinum L) varieties

Chickpea (Cicer arietinum L) is an important source of protein in several developing countries. Two commonly grown chickpea cultivars, HPG‐17 and C‐235, were evaluated for their physicochemical characteristics such as 100‐seed weight and density. Both chickpea varieties were subjected to various processing treatments and then analysed for their ascorbic acid content. The ascorbic acid content was generally found to be higher in the C‐235 variety, but it was higher in the HPG‐17 variety after germination. Significant results were obtained for both varieties after various treatments such as pressure cooking, germination, parching and solar cooking. It was found that the ascorbic acid content in both varieties decreased after all treatments except germination. © 2001 Society of Chemical Industry     

Electrical conductivity: a new tool for the determination of high hydrostatic pressure-induced starch gelatinisation

The degree of gelatinisation and electrical conductivity of wheat starch and tapioca starch suspensions (5% w/w) were determined after a pressure treatment of up to 530 MPa. With increasing pressure at a constant treatment time the degree of gelatinisation increased resulting in a gelatinisation curve similar to that of thermal gelatinisation. A pressure increase also caused an increase in electrical conductivity. A good linear relationship between the degree of gelatinisation and the electrical conductivity for both starches investigated was found. Since electrical conductivity correlates well with the degree of gelatinisation of starches after pressure treatment it is applicable for the quick and simple determination of pressure-induced starch gelatinisation.     

高压均质对大米蛋白功能特性及物化特性的影响

试验研究了不同均质压力(0~120 MPa)对浓度4%的大米蛋白功能特性和物化特性的影响。结果表明:随着压力的增加,大米蛋白的溶解性显著增加(P0.01),且在120 MPa下达到最大,为82.09μg/mL;乳化活性指数先增大后降低,在80 MPa下达到最大,为14.82 m~2/g;乳化稳定性指数降低。在压力的作用下,大米蛋白的粒径减小;离子键变化不显著(P0.05);氢键、疏水相互作用、巯基及二硫键的含量均发生显著性变化(P0.05),表明高压均质对大米蛋白的三维结构产生一定的影响。     

中温协同超高压处理对草莓汁贮藏品质的影响

研究中温协同超高压(45℃、400 MPa、15 min)技术对鲜榨草莓汁在4℃贮藏条件下的微生物、流体特性、组织和色泽稳定性的影响。结果表明:与单纯超高压技术相比,中温协同超高压处理能达到较好的杀菌效果且在贮藏期间无微生物增值(对数值小于1),霉菌、酵母菌均无检出;鲜榨草莓汁的流变学特性更偏向于假塑性流体、黏度增大;组织中果胶含量升高、悬浮稳定性增强;色泽稳定性方面亮度增加,而红色度减弱(a*减小)、黄色度增加(b*增大),△E变化较大,浊度与褐变度无明显差异(P0.05)。经中温协同超高压处理后,4℃贮藏期间鲜榨草莓汁的各项品质的稳定性均优于单纯超高压。     

HPLC法测定10个引自北美蓝莓品种果实中的糖酸组分及含量

采用HPLC法对10个引自北美的蓝莓品种果实中糖、酸组分及含量进行测定。结果表明,蓝莓果实中的可溶性糖以果糖和葡萄糖为主,果糖含量在18.916~73.899 mg/g之间,葡萄糖含量在19.194~79.521 mg/g之间;有机酸组分有草酸、奎宁酸、苹果酸、维生素C和柠檬酸,其中以柠檬酸为主,含量在1.174~15.069 mg/g之间,草酸最低,含量在0.018~0.046 mg/g之间。不同品种蓝莓果实的糖、酸含量存在明显差异,其中果糖和葡萄糖含量最高的品种是北空,柠檬酸含量最高的品种是伊丽莎白。糖酸比和甜酸比是影响果实风味的重要因素,10个蓝莓品种果实的糖酸比在2.342~27.488之间,甜酸比在285.953~3393.854之间,表现为北空>芝妮>圣云>友谊>美登>北陆>蓝光>爱国者>布丽吉塔>伊丽莎白。