可见分光光度法测定马蹄皮中总黄酮的含量

建立测定马蹄皮中总黄酮含量的光谱分析方法.以40%乙醇为溶剂,微波辅助提取马蹄皮中的总黄酮.以芦丁为标准样品,以NaNO2-Al(NO3)3-NaOH为显色剂,采用可见分光光度法在510 nm测量波长测定马蹄皮中总黄酮含量.回归方程A=0.0105 C+0.0014,相关系数R2=1,黄酮浓度在8.41 mg/L～82.88 mg/L范围内服从比耳定律.测定结果显示,马蹄皮中总黄酮的平均含量为1.59%,重现性试验RSD=1.38%(n=6),平均回收率99.6%(RSD=0.799%,n=6),精密度试验RSD=1.64%(n=6).     

PARTIAL PURIFICATION AND CHARACTERIZATION OF POLYPHENOL OXIDASE FROM FRESH-CUT CHINESE WATER CHESTNUT

The characteristics of polyphenol oxidase (PPO) from Chinese water chestnut (CWC) and its potential inhibitors for browning reactions were investigated. PPO was isolated from fresh‐cut CWC and was purified on a Sephadex G‐100 column, with a yield of total activity close to 10%. The molecular weight, Michaelis constant (K_m), substrate specificity, optimal pH and temperature of CWC PPO were examined. Kinetic studies indicated that the K_m and V_max values of CWC PPO for catechol were 10.32 mmol/L and 6.452 × 10⁴ U/min, respectively. The optimal pH and temperature for CWC PPO was 6.5 and 40C, respectively. Among the browning inhibitors tested, 4‐hexylresorcinol, at a concentration of 0.3 mmol/L, showed the strongest inhibition (70%) against the PPO activity of CWC, followed by 3.0 mmol/L N‐acetyl‐L‐cysteine with an inhibition of 53%.     

富含类黄酮的马蹄饮料的研制

介绍以马蹄皮为原料生产富含类黄酮的保健饮料的工艺流程和操作要点。通过正交试验和感官评定的方法确定饮料的最佳配方为：85％马蹄皮提取液,8％白砂糖,1．5％柠檬酸,1％碳酸氢钠,0．1％Vc和0．01％羧甲基纤维素钠。产品色泽淡黄,马蹄风味浓郁。     

超声法提取板栗黄酮的工艺

研究板栗中黄酮的最佳提取工艺条件.考察乙醇浓度、提取次数、提取时间、温度及物料比5个单因素对板栗中黄酮提取效果的影响.并在单因素的基础上进行正交试验得到黄酮提取的最佳工艺条件:板粟中黄酮的最佳提取条件为60%乙醇做溶剂,温度为70℃,提取时间为30min,料液比为1:9.以该优化条件提取时,板栗中黄酮的提取量为137.7 mg/g.     

荸荠片分段变温干燥加工工艺

对热风干燥生产荸荠片的加工工艺进行了试验研究。试验表明：采用0．2％柠檬酸溶液进行护色预处理和分段变温干燥方式可较好地防止产品干燥过程中发生褐变。分段变温干燥采用前段90℃干燥75min、后段65℃干燥180min，可得到风味色泽俱佳、复水性良好的荸荠片。     

EXTRACTION OF VOLATILE OIL FROM CUMIN (CUMINUM CYMINUM L.) WITH SUPERHEATED WATER

A comparative study of superheated water extraction (SWE) with two conventional methods including hydrodistillation and Soxhlet extraction was performed on cumin (Cuminum cyminum L.). The effect of some superheated water parameters at 20 bar pressure on the essential oil extraction from 4 g cumin seeds such as temperatures from 100 to 175C, particle size at 0.25 and 0.50 mm, and flow rates at 2 and 4 mL/min were investigated. Separation and identification of the components were carried out by gas chromatography‐flame ionization detector and gas chromatography‐mass spectrometry. The best operating conditions for the SWE of C. cyminum L. were determined to be 150C temperature, 0.50 mm mean particle size and 4 mL/min flow rate for 3‐h extraction time. The SWE method resulted in a more valuable essential oil with respect to the oxygenated components.     

菱角的保健功能及其产品开发进展

菱角是一种富含蛋白质、维生素、氨基酸且具有多种药用功效的植物，具有巨大的开发潜力。介绍了菱角的营养成分、保健功能，并对功能性产品的研发趋势进行了论述。     

CHARACTERIZATION OF CELL WALL POLYSACCHARIDES OF JICAMA (PACHYRRHIZUS EROSUS) AND CHINESE WATER CHESTNUT (ELEOCHARIS DULICIS)

Alcohol insoluble solids (AIS) from jicama and Chinese water chestnut were isolated and analyzed to elucidate the similarity in texture between these two crispy vegetables. Pectins were the largest AIS component of both vegetables, comprising approximately 50% of AIS. Further analysis showed a similar composition of water soluble, chelator soluble, and alkaline soluble pectins in both jicama and water chestnut. Water chestnut contained a much larger hemicellulose component and a correspondingly smaller cellulose and lignin component than jicama. Fractionation of the hemicellulose and examination of molecular weight distribution and neutral sugar composition of various fractions revealed major differences between the two vegetables. These differences in structure and composition of hemicellulose may explain the observed differences in textural properties of these two crispy vegetables.     

QUALITY CHARACTERISTICS OF MEAT FROM WILD RED DEER (CERVUS ELAPHUS L.) HINDS AND STAGS

The objective of the present study was to determine the chemical composition as well as physicochemical and sensory properties of meat ( musculus longissimus lumborum ) from red deer ( Cervus elaphus L.) hinds and stags harvested in forests of north-eastern Poland. Red deer meat was found to have a low fat content and a high content of total protein and water-soluble nitrogen in relation to total nitrogen. The total collagen content of meat was relatively low. Meat from hinds contained larger amounts of the above components (except for collagen). Meat from both hinds and stags had physical properties typical of venison, i.e., a dark color and a low pH level. Meat from hinds was characterized by better water-holding capacity. The relatively high TBARS value indicated lipid susceptibility to oxidation. The analyzed red deer meat had specific, but very good eating attributes (aroma, taste, juiciness, tenderness). Meat from stags was rated higher for taste and shear force.

PRACTICAL APPLICATION

Meat from animals raised under natural conditions has enjoyed a rise in popularity among consumers in recent years. The condition of "naturalness" is met by venison, which at the same time is known for its very high nutritive value and specific, but highly desirable, sensory properties. However, the nutritional and sensory qualities of venison should be analyzed in view of their great variation resulting from the impact of genetic and environmental factors, which remains insufficiently investigated, particularly with regard to wild populations.     

COOKING CHARACTERISTICS OF FOUR CULTIVARS OF BAMBARA GROUNDNUTS SEEDS AND STARCH ISOLATE

The proximate composition and textural changes during the cooking of four bambara groundnut (Voandzeia subterranea) seed cultivars were evaluated. Bambara groundnut seeds contained 18–21% protein 6–8% fat, 8–10% moisture and 1.2–2.6% ash. Changes in hardness in relation to cooking time was monitored for 2 h. The cooking time for softening was shorter for the cream and brown colored cultivars than for the red black colored cultivars. The swelling and viscosity properties of starch isolates prepared form the seeds were studied. There were no varietal differences (p≤0.05) in starch viscosity and swelling properties among cultivars. Estimation of tannin content of bambara groundnut seeds showed that tannin contents of the red and black seed cultivars (0.96% and 1.1%, respectively) were significantly higher (p≤0.05) than the tannin contents of cream and brown seed cultivars (0.68% and 0.72%, respectively).     

BROWNING INHIBITION AND QUALITY MAINTENANCE OF FRESH-CUT CHINESE WATER CHESTNUT BY ANOXIA TREATMENT

Experiments were conducted to test the effects of anoxia treatments on the quality of fresh‐cut Chinese water chestnut (CWC). Fresh‐cut CWC was exposed to pure N₂ for 0 (control) or 4 h, then placed in trays overwrapped with plastic film and finally stored at 4C. Changes in surface discoloration, eating quality, disease incidence, concentrations of total soluble solids and titratable acidity, activities of phenylalanine ammonia lyase (PAL) and polyphenol oxidase (PPO), and membrane permeability were analyzed. The short‐term anoxia treatment significantly inhibited surface discoloration and disease development, and markedly reduced the loss of eating quality in association with a higher concentration of total soluble solids. Exposure of fresh‐cut CWC to pure N₂ gas for 4 h significantly reduced membrane permeability, but it increased PAL and PPO activities. Thus, the browning inhibition of the fresh‐cut CWC by the short‐term anoxia treatment may be because of the maintenance of compartmentation between enzymes and their substrates, preventing enzymatic reaction. The result suggests that short‐term anoxia treatment exhibits potential for extending the shelf life of fresh‐cut CWC.