鲜白果和熟制白果挥发性成分的分析

采用固相微萃取和气质联用(SPME-GC-MS)技术对鲜白果、微波熟制白果和煮制熟制白果挥发性化合物进行测定,并利用主成分分析法(PCA)对三者的挥发性化合物进行比较分析。结果表明:熟制白果与鲜白果挥发性化合物存在较大差异,从中共检出66种挥发性化合物。鲜白果中检出44种,主要挥发性成分为醛类;微波熟制白果中检测出35种挥发性成分,醇类相对含量较高;煮制熟制白果中有31种挥发性成分被检测出,萜类含量和种类最高。PCA分析发现新鲜白果的挥发性成主要指向醛类,微波和煮制熟制白果的挥发性成分主要指向萜类。     

微波辅助提取苹果籽油的工艺研究

采用正交设计法研究了微波加热时间、料液比和微波加热温度对苹果籽油得率的影响,结果得出最佳提取工艺条件为：微波加热时间3min、料液比1：24、微波加热温度50℃。在此条件下,苹果籽油得率为25．51％。     

Nutritional quality of legume seeds as affected by some physical treatments 2. Antinutritional factors

Raw and treated cowpea, pea and kidney bean seeds were investigated for their content of antinutritional factors including tannins, phytic acid, trypsin inhibitors and oligosaccharides. Treatments applied included water soaking, boiling, roasting, microwave cooking, autoclaving, fermentation and micronization. Kidney bean contained the highest antinutrient content among all investigated seeds. The least tannins and phytic acid contents were recorded in Canadian cowpea while Canadian pea showed the lowest TIA. All treatments conducted caused significant decreases in tannins, phytic acid, TIA and oligosaccharides as compared to the raw seeds. Boiling caused the highest reduction in tannins followed by autoclaving and microwave cooking. Autoclaving and fermentation were the most effective in reducing phytic acid content. Heat treatments (boiling, roasting, microwave cooking and autoclaving) brought a total removal of trypsin inhibitors of all samples. Furthermore, autoclaving caused the highest reduction in oligosaccharides followed by fermentation while the least reductions were caused by either roasting or micronization with no significant difference between these two treatments.     

微波和红外处理对油茶仁油组成和稳定性影响规律

通过微波和红外两种方式加热油茶籽,研究了油茶仁的水分、含油率以及压榨油茶仁油的水分、氧化稳定时间、分子质量组成、液质成分等的变化规律.研究结果表明,微波和红外加热均可有效去除油茶仁和油茶仁油中的水分,相比油茶仁随加热强度增大水分降低的规律,油茶仁油中水分在加热后期有略微上升.不同功率微波处理油茶籽后,油茶仁油的氧化稳定...     

Effect of dry heat on the in vitro digestibility and trypsin inhibitor activity of chickpea flour

The effect of a dry heat treatment on trypsin inhibitors, protein quality and molecular weight of products obtained from enzymatic hydrolysis of chickpea flours was analysed in order to use chickpeas as food protein hydrolysates. Chickpea flour obtained from dehusked seeds was processed under different conditions, either by heating or enzymatic treatment. Heat treatment at 140 °C for varying times (1–24 h) inactivated trypsin inhibitors and facilitated enzymatic treatment but showed an unacceptable loss in the nutritional quality of the protein for heating times longer than 6 h. Enzymatic treatment with a commercial protease, Alcalase 0.6L, at pH 8 and 50 °C, increased the protein nutritional value of the chickpea by breaking the protein chains into shorter peptide chains more suitable to human nutrition.     

微波对植物油品质的影响

基于微波加热原理，并通过分析植物油中主要化学成份的介电特性，说明植物油受微波作用时，其品质会受到一定程度的影响，而且，用微波干燥油料，能较好地保持毛油的品质。本文重点综述这一领域的研究进展。     

Microwave Heating Affects Composition and Oxidative Stability of Sesame (Sesamum indicum) Oil

The effects of microwave heating on antioxidative components and lipid quality of sesame seeds were studied. Amounts of antioxidative components were 576, 18, and 8 mg/kg oil for γ-, δ-, and α-tocopherols; 6,824, 5,642, and 54 mg/kg oil for sesamin, sesamolin, and sesamol, respectively. During microwave treatments, concentrations of tocopherols, sesamin and sesamolin gradually decreased, and ca. 20% of these dominant components was lost after 30 min heating. However, microwave treatments for 16 to 20 min, which would be optimal to prepare sesame oil with better quality, still retained over 85% of the antioxidative components (with few exceptions) and caused no significant chemical changes in lipids.     

Proteinaceous Inhibitors of Trypsin and of Amylases in Developing and Germinating Seeds of Pigeon Pea ( Cajanus cajan(L) Millsp)

Inhibitors of trypsin and amylase in the extracts of developing seeds of 12 pigeon pea cultivars were analysed using a gel-X-ray film contact print technique and an enzyme-inhibitor assay, respectively. The inhibitors of amylase and trypsin in the extracts of germinating seeds of a pigeon pea cultivar (BDN2) were also studied. Nine trypsin inhibitor bands were detected in mature seeds of all the 12 cultivars. Inhibitory activities against amylase and trypsin were not detected in the extracts of seeds collected 11 and 27 days after flowering (DAF) by the enzyme-inhibitor assay. However, up to three trypsin inhibitor bands could be detected in the extracts of seeds collected 27 DAF by the gel-X-ray film contact technique. Two new slow-moving trypsin inhibitor bands were detected in the extracts of germinating seeds of BDN2 cultivar. These bands were prominent in extracts of seeds 10 days after germination (DAG). The amylase inhibitors and trypsin inhibitors in pigeon pea seeds are late synthesised proteins, their highest levels were observed in mature seeds and they were found to be slowly degraded during germination. Significant inhibitor activities were observed even 15 DAG. The amylases in developing seeds are insensitive to endogenous inhibitors.     

Effect of soaking,dehulling, and cooking methods on certain antinutrients and in vitro protein digestibility of bitter and sweet lupin seeds

Effect of several physical treatments (soaking, dehulling, ordinary cooking, microwave cooking, and autoclaving) on the level of antinutrients and in vitro protein digestibility of bitter and sweet lupin seeds were investigated. The raw bitter and sweet lupin seeds were found to contain phytic acid, tannins, trypsin inhibitor activity, and lectin activity, but α-amylase inhibitor was absent. Dehulling significantly increased the levels of phytic acid (PA), trypsin inhibitor activity (TIA), and tannins, but lectin activity was not changed. Also soaking in bitter (for 96 hr) and sweet (for 24 hr) seeds caused a significant increase in these factors except lectin activity. Cooking methods differently affected the levels of the antinutrients. Thus, PA increased but tannins were not changed, on the other hand TI and lectin activities were inactivated; ordinary cooking and autoclaving were the most effective in both seeds. For combination effect, soaking following cooking treatments significantly decreased PA, tannins, and lectin activity, but increased TIA in both seeds. Moreover, dehulling following soaking and cooking methods resulted in a significant increase of PA, TIA, and tannins. In vitro protein digestibility (IVPD) of raw bitter and sweet lupin seeds were 78.55 and 79.46%, respectively and it was improved by all processing methods; soakingdehulling after autoclaving was the most effective in both seeds. Although some treatments increased the level of antinutrients, they improved IVPD. Therefore, the studied antinutrients are not the only responsible factor for lowering IVPD.     

Process Intensification by Experimental Design Application to Microwave-Assisted Extraction of Phenolic Compounds from <Emphasis Type="Italic">Juglans regia</Emphasis> L.

Microwave-assisted extraction was applied to Juglans regia L. fresh male flowers and unripe walnut seeds to evaluate the total phenolic contents of the extracts as well as the percentage of water-soluble polyphenols. The research was planned using the Design of Experiments technique to investigate the role on the extraction efficiency of different parameters, such as temperature, time and number of microwave heating cycles, together with their possible interactions. Optimization was achieved by applying a Response Surface Methodology comprising a three-factor, two-level, full-factorial Face-Centred Central Composite Design. The two input variables with a significant effect on the recovery of phenols from fresh male flowers were the extraction temperature and the number of microwave cycles. In the case of unripe walnut seeds, a linear two-factor interaction model was selected, with significant interactions occurring between temperature and time, and time and number of microwave cycles. The best experimental conditions were as follows: 100 °C, 6 min, three microwave heating cycles and 22.7 ± 0.2 mg gallic acid equivalent (GAE)/g (total phenolic content, PC); energy consumption calculations suggested slightly different conditions: 60 °C, 30 min, three microwave heating cycles and 20.7 ± 0.3 mg GAE/g (TPC).     

MICROWAVE HEATING AND γ-IRRADIATION TREATMENT OF RAPESEED (BRASSICA NAPUS)

Rapeseeds were treated with different doses of γ-irradiation and microwave heating of oil extraction. Improvement of the oil extractivity was achieved after microwave treatment while the quality parameters of crude oil were not significantly changed except the total phosphorus content, which was nearly four times higher compared to that of the control. It seems that microwave treatment damages membranes and thus higher amounts of phospholipids may be released into the crude oil. Microwave heating also resulted in a reduction of enzyme activities and lower protein content in buffered seed extracts due to partial protein denaturation. The differences in protein profiles of treated and untreated seeds were also demonstrated by SDS PAGE. The protein denaturation was observed for all types of proteins. γ-irradiation had practically no effect on the oil quality parameters and did not change its yield.     

Effects of Microwave Heating and Gamma Irradiation on Phytate and Phospholipid Contents of Soybean (Glycine max. L.)

The effect of microwave heating and gamma irradiation treatments on phosphorus compounds of soybean seeds were studied. Inorganic phosphorus was significantly (P < 0.05) increased while, phytate and phospholipids were significantly decreased when soybean seeds were microwave-heated for 9 min or more. Furthermore, gamma-irradiation treatments of 20 KGy or more significantly increased inorganic phosphorus and decreased phytate and phospholipids of the beans. Two dimensional thin-layer chromatography was employed to study the phospholipid pattern. Gamma-irradiation at doses from 40 to 100 KGy produced lysophosphatidylcholine and phosphatidic acid. The data of this study showed that, the increase of inorganic phosphorus was mainly due to the decomposition of phytic acids and phosphates of inositol.     

Trypsin inhibitor content in some varieties of soya bean (Glycine max L.) and sunflower seeds (Helianthus annuus L.)

Some varieties of soya beans and sunflower seeds were analysed for protein, fat, moisture and trypsin inhibitory activities. The soya beans were high in protein content and all of them were equally high in trypsin inhibitory activity. Some varieties of sunflower seeds were adequate in fat and proteins, some were very low and others were reasonably free from trypsin inhibitors. Extensive cultivation of the sunflower seeds having adequate amount of fat and protein, but free from trypsin inhibitor should be encouraged.     

原子光谱法测定金花葵花瓣及种子中微量元素

金花葵微量元素的测定多采用原子光谱法,但因实验条件、样本预处理方法不一致,各测定方法间的重现性和可比性较差。采用原子吸收分光光度计测定微量元素铜、镁、铁、锰、铅、锌,采用原子荧光分光光度计测定微量元素硒。实验详细研究了微波消解与电热板消解法两种消解方法对含量测定的影响,对金花葵花瓣和种子中的微量元素含量进行了比较。结果表明微波消解法更有利于微量元素含量的测定,精密度与重现性更高。金花葵种子与花瓣相比,种子中的微量元素锌、镁、锰等含量均比花瓣中高,金花葵花瓣及种子中都含有微量元素硒,种子中的微量元素含量达0.063 5 mg/kg,花瓣中的含量为0.027 2 mg/kg。微量元素铅含量没有超标,金葵花种子的药用价值更高。     

微波双酶协同水解大豆分离蛋白制备小分子肽的研究

研究微波加热条件下，用碱性蛋白酶和胰蛋白酶双酶水解大豆分离蛋白。以氨基氮为评价指标，确定了单酶水解工艺，双酶分步水解的顺序和制备小分子大豆多肽的最佳条件，并通过毛细管电泳方法对水解多肽的分子量进行测定。实验表明：双酶水解优于单酶，制得的大豆肽分子量主要集中在5000以下。     

Combined microwave and enzymatic treatments for ��-lactoglobulin and bovine whey proteins and their effect on the IgE immunoreactivity

Effect of combined microwave (MW) and enzymatic hydrolysis on the human immunoglobulin E (IgE)-binding properties of ??-lactoglobulin (??-lg) and other whey proteins (WP) was investigated. Separated ??-lg and full whey protein isolate (WPI) were hydrolyzed with trypsin, chymotrypsin, mixture of trypsin/chymotrypsin, and pepsin at three microwave power levels: 50?W during 1 and 5?min, 100 and 200?W during 1 and 3?min. The immunoreactivity of the obtained hydrolysates resulting from combined microwave protease treatment was assessed using sera of young patients allergic to bovine whey proteins. The application of microwave treatment at 200?W enhances the hydrolysis of ??-lg by pepsin in 3?min and decreases significantly its immunoreactivity. The extensive hydrolysis of the microwave-treated ??-lg and WPI with trypsin, chymotrypsin, and the mixture of trypsin with chymotrypsin did not have an impact on the IgE binding of the products obtained in all the studied conditions.     

Influence of processing on available carbohydrate content and antinutritional factors of chickpeas

 The effect of chickpea processing (soaking, soaking plus cooking and dry heating) on the content of available carbohydrate (monosaccharides, disaccharides and starch) and antinutritional factors (α-galactosides and trypsin inhibitor activity) was studied. Soaking produced a reduction in available carbohydrates (19–20%) and α-galactosides (16–27%), and either did not affect or caused a slight reduction of trypsin inhibitor activity (TIA) in chickpeas. Soaking plus cooking brought about a larger decrease in available carbohydrates (23–24%) and α-galactosides (45–58%), and completely eliminated TIA. Dry heating caused a 24% reduction in available carbohydrates, a 46% decrease in α-galactosides and a 27% decrease in TIA. Overall, cooking the presoaked seeds in water, acidic or basic solution seems to be adequate to obtain a chickpea flour with a large reduction in antinutritional factors (α-galactosides and TIA) and also a high level of available carbohydrate content. Received: 22 April 1999 / Revised version: 28 June 1999     

不同加热方法对大米主要化学成分及食味的影响

以大米为对象,研究常规加热、微波加热和混合加热对不同品种大米品质的影响,为微波防虫防霉和生产应用提供参考。结果表明,加热方法和品种对大米品质的影响有差异,水浴加热对大米品质的影响大于微波处理。在试验范围内,先用常规加热将大米预热,再用微波处理的混合加热法对大米品质的影响小于单独加热。预热后大米温度、微波功率和微波加热时间对大米品质有极显著或显著影响。建立了预热后大米温度、微波功率和微波加热时间与大米的水分含量、直链淀粉含量等主要化学成分和食味之间的多元线性回归方程,具有较高的拟和精度。     

微波对天麻鱼头汤营养和安全性影响

为探讨微波加工对药膳鱼汤品质影响,以天麻、鱼头为原料,分别采用微波炉和传统电炖锅加热的方法,研究其水溶性蛋白、游离氨基酸、矿物质、天麻素、嘌呤和感官品质的变化规律。结果表明:微波加热更有利于小分子物质的溶出,如氨基酸、矿物质、天麻素和嘌呤等,微波煲汤中游离氨基酸含量甚至高达电炖锅的1.5倍,对蛋白质等大分子物质的影响较小;在安全性方面,微波200 W小功率的煲汤或者400 W大功率短时间煲汤产生的嘌呤含量均不超过15 mg/L,既符合痛风病人安全需求又改善了鱼汤的风味;在感官评价方面,采用微波炉400 W煲汤1 h的感官得分可以达到与电炖锅煲汤3 h相类似的效果,可以将煮制周期缩短2 h,微波加热可大大缩短煲制时间,是一种更加高效的煲汤方式。     

腔体内壁脊形凹槽对微波反应器加热效率及均匀性的影响

提出在微波反应器腔体内壁设置脊形凹槽的优化策略,研究在保证加热效率的前提下提升微波加热的均匀性。利用有限元法仿真研究不同凹槽结构参数对微波反应器加热效率和均匀性的影响。研究结果表明:脊型凹槽结构能有效提升微波反应器的加热效率和加热均匀性。优化后微波反应器的加热效率达到98.75%,与微波腔壁光滑时相比,均匀性最大提升幅度达到58.54%。