白英果提取物清除DPPH自由基活性研究

确定了以分光光度法测定天然抗氧化剂清除2,2-Diphenyl-1-picrylhydrazyl（2，2-二苯基-1-苦肼基，DPPH）自由基能力的条件。通过测定芦丁、槲皮素、抗坏血酸、没食子酸的自由基清除率曲线，提出以IC50值作为评价试样清除DPPH自由基能力的指标，并将此应用于白英果提取物清除DPPH自由基能力的测定，测得白英果乙醇提取液、乙酸乙酯提取液以固形物计算的IC50值分别为0．230和1．010。     

玉米须黄酮清除自由基活性的研究

利用二苯代苦味酰基自由基体系、H2O2/Fe2+产生的羟基自由基体系、超氧阴离子自由基体系对玉米须黄酮粗提物、乙酸乙酯与正丁醇萃取物的体外清除自由基的能力进行研究,并以芦丁的测定值为对照.试验结果为:清除DPPH自由基的能力依次为:玉米须黄酮粗提物>正丁醇萃取物>乙酸乙酯萃取物.各试样达到最大清除率的浓度及清除率分别为:1、2、2g/L及93%、78%和71%;清除羟自由基的能力依次为:玉米须黄酮粗提物>乙酸乙酯萃取物>正丁醇萃取物,当试样浓度为20 g/L时,清除率达到最大,依次为92.04%、82.6%和56.5%;清除超氧阴离子自由基的能力依次为:玉米须黄酮粗提物>乙酸乙酯萃取物>正丁醇萃取物,当试样的浓度为20g/L时,清除率达到最大,依次为94.8%、90%和58%.结果表明,各试样清除羟自由基和超氧阴离子自由基的效果优于芦丁的效果,玉米须黄酮具有较好的清除自由基的能力.     

化学发光法测定蓝莓花色苷对氧自由基的清除作用

用化学发光法研究蓝莓花色苷对超氧阴离子自由基(O2-·)、羟基自由基(·OH)、H2O2的清除能力,并与抗坏血酸进行比较.研究结果表明:蓝莓花色苷对O2-·、·OH、H2O2等活性氧(ROS)均具有清除和抑制作用且清除作用与浓度呈剂量关系.蓝莓花色苷对O2-·、·OH的清除能力强于抗坏血酸,但对H2D2的清除作用不如抗坏血酸.蓝莓花色苷清除O2-、·OH、H2O2的IC50分别为81.36、7.21、80.43mg/L,其中对·OH的清除能力最强.     

迎春花黄色素的超声提取及清除自由基作用研究

利用超声波作用,提取迎春花黄色素,对迎春花黄色素提取的影响因素:溶剂、酸度、超声时间、物料比等,作单因素试验和正交试验,研究迎春花色素对羟自由基、超氧自由基的清除作用.结果表明,超声波作用下提取迎春花色素的最佳条件是:溶剂80%的乙醇,pH=7、物料比1:10(g/mL),超声时间为20min,温度为70℃,提取级数是3级.迎春花色素对OH-·、O2-·自由基有清除作用,清除率随色素浓度的增加而增大,随时间的增加而减小.     

REDUCTION OF FUNGI AND MYCOTOXINS FORMATION IN SEEDS BY GAMMA-RADIATION

Ninety samples of maize, chick-peas and groundnut seeds collected from the Egyptian market were found to be heavily contaminated by molds. Alternaria, Aspergillus, Cladosporium, Eurotium, Fusarium, Mucor, Penicillium and Rhizopus were the most common fungal genera isolated from nondisinfected seeds . Aspergillus alutaceus, A. flavus, Fusarium verticillioides and F. oxysporum were isolated from all surface-disinfected seeds and were reported to produce ochratoxin A, aflatoxin B₁ and zearalenone, respectively. Irradiation at a dose 4.0 kGy reduced the mold growth greatly relative to unirradiated controls. There was no growth at dose 5.0 kGy. On the basis of the radiation survival data, the decimal reduction values D₁₀ for A. alutaceus, A. flavus and F. verticilliodies were 0.70. 2.10 and 0.93 kGy in maize. A dose of 5 kGy inhibited the toxigenic molds and mycotoxin formation in seeds. Aflatoxin B₁ and ochratoxin A were detected in maize and chick-peas, whereas zearalenone was detected in maize samples. Application of radiation at a dose of 6.0 kGy detoxified aflatoxin B₁ by 74.3–76.7%, ochratoxin A by 51.3–96.2% and zearalenone by about 78%.     

PRODUCT DEVELOPMENT AND NUTRACEUTICAL ANALYSIS TO ENHANCE THE VALUE OF DRIED FRUIT

ABSTRACT

Value‐added fruit products suitable for production by small‐scale farmers and processors were developed and evaluated. Apples, blueberries, peaches and strawberries from local growers were processed into a dried fruit product. The total phenolics, total anthocyanins and oxygen radical absorbing capacity (ORAC) were determined. Drying the fruit concentrated total phenolics, total anthocyanins and ORAC levels as compared to fresh fruit. The nutraceutical components of the blueberries, peaches and strawberries of the local dried fruit were higher than those of commercial dried fruit purchased at a natural food store. The dried fruit from both the local and commercial fruits was used to create a fruit pie filling for consumer evaluation. Consumer acceptance of fruit pie filling from dried fruit grown locally and dried commercial fruits was evaluated using a 9‐point verbal hedonic scale and a 5‐point Just About Right scale. In terms of consumer evaluation, the pie fillings made from local dried fruits were either better or at parity with those from commercial products. In addition to the nutraceutical benefits, the pie fillings were consumer acceptable products that could represent an avenue for small‐scale farmers to add value to surplus fruit.

PRACTICAL APPLICATIONS

Complete utilization of fruit crops is a key component to the success of small farm operations. Excess fruit crops can be dried (or processed in other manners) and used to create many value‐added products. Increased consumer awareness of healthy food products provides a niche market for these fruit products. In this research, the nutraceutical benefits of fresh and dried apples, blueberries, peaches and strawberries were investigated and the consumer overall acceptance of a pie filling produced from these dried fruit was shown.

     

离子色谱法测定荔枝核及其732树脂洗脱液的游离氨基酸

为测定荔枝核中的游离氨基酸,采用ICS-2500离子色谱分析仪,分别测定了荔枝核提取液与732阳离子交换树脂洗脱液中的氨基酸的组成和含量.离子色谱条件:固定相为Amino PACPA-10离子交换柱,流动相:250mmol/LNaOH、1 mol/L NaAC和水作为洗脱液进行梯度洗脱,柱温30℃,流速0.25mL/min.在稀释100倍的荔枝核提取液中舍有12种游离氨基酸,其中苏氨酸、精氨酸和甘氨酸总相对含量为64%,且含有3种未知氨基酸,但未知氨基酸不稳定,离子交换树脂未起到预期的分离效果.因此,离子色谱法可有效的检测荔枝核中及分离纯化过程中的游离氨基酸.其中未知氨基酸的适宜分离条件有待进一步研究.     

现代分析仪器验证淀粉自由基的存在及其不稳定性

用生物化学发光测量仪（SBL）和顺磁共振仪（EPR）证明了经Co60照射过的淀粉确实能产生淀粉自由基，且随着辐照剂量增加，淀粉自由基的数量增多。同时，SBLI中测得发光值和EPR信号强度随着淀粉自由基存放时间延长而减小和衰减，说明淀粉自由基具有不稳定性。另外，经EPR测定，Co60照射产生的淀粉自由基其特征g值为2.003。     

FRUIT TEXTURE—AN OVERVIEW OF TRENDS AND PROBLEMS

The development of the Magness Taylor Pressure Tester in 1925 led to major advances in understanding and controlling factors that affect the firmness of fruits. Recent advances in elucidating the complex nature of texture and in improved instrumentation should lead to another round of major advances in understanding and controlling factors that affect the textural properties of fruits. The trend to mechanical harvesting will probably lead to fruits with firmer texture that can withstand the rigors of machine harvesting. The difficulty of duplicating the textural properties of fruits is the principal obstacle to the development of fruit analogs.     

棉籽蛋白多肽的制备及对DPPH自由基的清除作用

以棉籽蛋白为底物,采用木瓜蛋白酶为水解酶进行水解,以DPPH清除率来测定其水解产物的抗氧化能力.结果表明:木瓜蛋白酶最适作用条件:pH值为8.0,酶与底物浓度比[E]/[S]为10%,温度为55℃.不同水解度(DH)的棉籽蛋白多肽清除DPPH自由基的能力不同,当水解度为3.81%时,DPPH自由基的清除率最高可达70.7%.     

PEKMEZ-DAIRY DESSERTS FORTIFIED WITH SPRAY-DRIED DAIRY POWDERS: EFFECTS OF THE INTERACTION BETWEEN SKIM MILK POWDER, YOGHURT POWDER AND BUTTERMILK POWDER BY A MIXTURE DESIGN APPROACH

A mixture design approach was used to evaluate the interactions between skim milk powder (SMP), yoghurt powder (YP) and buttermilk powder (BMP) on rheological and sensory properties of dairy dessert mixture samples (DDMS). DDMS was prepared with pekmez powder, which was obtained by spray drying of pekmez, also known as concentrated grape molasses. Among the dairy powders, YP was the component that had the most effect on the viscosity of DDMS. The liking of the panelists was more prominent for the dairy dessert samples including the higher concentrations of YP. Optimum values of SMP, YP and BMP in the mixture were found to be 12–46%, 41–90% and 0–39%, respectively with respect to sensory properties.

PRACTICAL APPLICATIONS

The compositional properties of dairy powders can be changed by their usage at particular combinations, which could give rise to an improvement in their rheological and sensory properties. Such modifications would be of great economical importance to food industry. Dairy powders can be used to improve these properties when optimum combination levels of these dairy powders are taken into consideration. Therefore, information obtained in this study may be useful in practical industrial food product process monitoring and development.     

大麦多糖的提取及清除羟自由基活性研究

研究大麦多糖水提法的工艺条件和清除羟自由基活性。用淀粉酶和蛋白酶酶解除去大麦中的淀粉和蛋白质。以多糖得率为考察指标,采用正交试验考察提取温度、料液比、提取时间等因素对多糖得率的影响,优化提取工艺条件。采用水杨酸法考察大麦多糖清除羟自由基活性。研究结果表明,酶解25g大麦粉,耐高温α-淀粉酶的最佳用量为0．14mL,中性蛋白酶的最佳用量为0．3g。水提法的最佳工艺条件为温度100℃,料液比1：20,时间3h,此条件下大麦多糖的得率为3．10％,含量为64．29％。大麦多糖具有清除羟自由基的能力,当其浓度为5．88g,L时清除率达50％,浓度为20g／L时清除率达97．14％。     

果蔬多酚氧化酶酶促褐变的控制

在介绍多酚氧化酶酶促褐变原理的基础上,着重阐述通过原料选择、钝化酶活性、抑制酶促反应、改变反应产物、驱氧处理、复合抑制等途径控制果蔬酶促褐变的方法.     

AN ENGINEERING METHOD TO EVALUATE THE CRISP TEXTURE OF FRUIT AND VEGETABLES

Precise measurements of the deformation and fracture behaviour of food can be difficult because of problems associated with the produce, for example, sample preparation, gripping, size and geometry. The aim of this study was to characterise fruits and vegetables in terms of fracture properties using an established engineering test method and geometry, the Single-Edge Notched Bend (SENB). The SENB geometry was found to be readily applicable to crisp food produce such as carrots, celery, and apples, which exhibit linear elastic behaviour up to fracture. Fracture toughness and fracture energies were found to be in the range 10–50 kPa m^1/2 and 40–400 Jm⁻², respectively. The structure of these materials was confirmed, using confocal microscopy, and related to the observed fracture behaviour. Cell size and intercellular spaces influenced the values of fracture toughness and fracture energy.     

RIPENING AND QUALITY CHANGES IN MANGO FRUIT AS AFFECTED BY COATING WITH AN EDIBLE FILM

Mango fruit has a relatively short storage life of about 2 to 3 weeks at 13C. In order to prolong the storage life of ‘Haden’ mangoes, fruit were coated with 3 concentrations (8,16 and 24 g.L^?1) of the edible coating film “Semperfresh” and then stored at 13C and 85% RH. Fruit were then evaluated every 4 days for up to 32 days for total soluble solids (TSS), titratable acidity (TA), pH, firmness, weight loss, color of the skin, and ascorbic acid content. All 3 concentrations applied to the fruit affected fruit ripening. TA, firmness, and green color were higher in coated fruit, and weight loss, SST, and pH were lower compared with the noncoated fruit. “Semperfresh” had no effect on decay development. Ascorbic acid decreased in all stored fruit, but this decrease was slower in coated fruit, and there were no significant differences between the different “Semperfresh” concentrations.     

SPECTRAL COMPOSITION OF EATING SOUNDS GENERATED BY CRISPY, CRUNCHY AND CRACKLY FOODS

Separate air and bone conducted food sounds generated by six subjects biting into eight foods were recorded and analysed by a fast Fourier transform (FFT) signal analyser. A panel of 60 subjects classified the 8 foods according to their texture: crispy, crunchy and crackly and these textural characteristics were described by spectral characteristics of biting sounds. Crispy foods (such as extruded flat breads) were found to generate high pitched sounds that show a high level of frequencies higher than 5 kHz, especially for air conduction. Crunchy foods (such as raw carrot) generate low pitched sounds with a characteristic peak on frequency range 1.25 to 2 kHz for air conduction. And crackly foods (such as dry biscuits) generate low pitched sounds with a high level of bone conduction. We hypothesize that discrimination between crunchy and crackly foods could be due to vibrations propagated by bone conduction that also generated vibrotactile sensations.