Effects of High CO_2 Pretreatment on the Quality of Fresh-Cut Potatoes

Effects of short-term high CO_2 pretreatment on quality of fresh-cut potatoes were studied. Potatoes were treated under 90% CO_2 for 18 h, peeled, cut, dipped in 1% ascorbic acid or distilled water for 3 min, packed in polyethylene bags and stored for 12 d at 4 ℃. Non-treated potatoes were used as the control. High CO2 pretreatments ensured maintenance of a high level of CO_2 in headspace of packages containing fresh-cut potatoes. Both the growth of total aerobic bacteria in initial stages of post-cut storage and browning index of the cut surface were lower in high CO_2 treated cut potato. Anti-browning effect of high CO_2 pretreatment was decreased when applied in combination with ascorbic acid. Soluble solids, pH, titratable acidity and flesh firmness of fresh-cut potatoes were not affected by high CO_2 treatment. Therefore, high CO_2 treatment before slicing could be effective method to maintain quality of flesh-cut potatoes.

A novel mitigator of enzymatic browning--hawthorn leaf extract and its application in the preservation of fresh-cut potatoes

Objectives:The purpose of this study was to evaluate the antibrowning functions of hawthorn leaf extract on fresh-cut potato and its possible mechanism.Materials and Methods:Fresh-cut potatoes were treated with different concentrations(0.01%,0.05%,and 0.1%)of hawthorn leaf extract and preserved at 4 C for 8 days.The appears nee and colour of potato slices were evaluated,along with the content of the phenol,malondialdehyde(MDA),and hydrogen peroxide(H2O2)during cold storage.Meanwhile,the activities of polyphenol oxidase(PPO),peroxidase(POD),phenylalanine ammonia-lyase(PAL),lipoxygenase(LOX),catalase(CAT),superoxide dismutase(SOD),and the antioxidant capacity were determ in ed.Furthermore,the composition of hawthorn leaf extract was analyzed by high-performance liquid chromatographytandem mass spectrometry(HPLC-MS/MS).Results:The addition of hawthorn leaf extract effectively delayed the browning process.It not only enhanced the CAT activity and antioxidant capacity but also reduced the LOX activity and accumulation of MDA and H_(2)O_(2).Meanwhile,the activities of PPO,POD,and PAL as well as the content of phe nol were con trolled.Additionally,25 phe nols,34 flavonoids,and 5 proa nthocya nidins were identified through high-performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS),ideluding caffeic acid,quercetin and catechol.Conelusion:Hawthorn leaf extract significantly alleviated the browning of fresh-cut potato.It could serve as a n atural an tibrowning alter native by stabilizing the membra ne and modulating reactive oxygen species and redox reactions.

Effects of 1-MCP and Chitosan on Active Oxygen Metabolism and Quality of Fresh-cut Potato during Storage

[Objective] The research aimed to study the effects of 1-methylcyclopropene （1-MCP） and chitosan on active oxygen metabolism and quality of fresh-cut potato during storage. [Method] The fresh-cut potato slices were respectively treated with 1- MCP （2 μl/L）, chitosan or 1-MCP ＋ chitosan. During the storage period, the contents of superoxide anion （02）, malondialdehyde （MDA）, hydrogen dioxide （H202） and Vita- min C （Vc）, the activities of polyphenol oxidase （PPO）, peroxydase （POD） and super- oxide dismutase （SOD） as well as the respiratory rate of the fresh-cut potatoes in all the treatments were determined every day. The fresh-cut potato slices treated without any reagents were used as control. [Result] 1-MCP Treated could significantly de- creased the respiratory rate, PPO activity and the accumulations of 02 , H202 and MDA, increased the activities of SOD and POD and slowed down Vc content reduc- tion. On the contrary, potato treated with chitosan significantly inhibited the POD activi- ty in fresh-cut potato. Compared with the control, the combination of 1-MCP and chi- tosan showed a little but not significant better effects on potato preservation. [Conclu- sion] 1-MCP Treated showed the best effects on potato preservation.

Hot Potatoes在外语教学中的应用

Hot Potatoes软件具有简便易用的特点,有助于辅助缺乏计算机技术基础的外语教师制作多种形式的网页式习题。在计算机辅助外语教学中应用Hot Potatoes能够帮助学生整合课堂与课外学习,巩固课堂所学并开展自主学习,同时还能够帮助学生适应新的四六级网考评估模式。

Extraction Characteristics of Anthocyanins from Preliminarily-processed Products of Purple Sweet Potatoes during the Gelatinization Process

Objective] This study aimed to investigate the method for efficient utilization and development of purple sweet potatoes. [Method] Purple sweet potatoes were dried at two specific temperatures and prepared into preliminarily-processed products for gelatinization simulation to analyze the extraction amount of anthocyanins from gelatinized samples at different gelatinization stages. [Result] During the gelatinization process, the extraction rate of anthocyanins from purple sweet potato samples reached the highest as the temperature rised from 90 ℃ to 95 ℃,and the extraction amount of anthocyanins reached the maximum at 15 min postheat preservation at 95 ℃. Purple sweet potato samples dried at 60 ℃ exhibited larger retention amount, larger maximum extraction amount and higher maximum extraction rate of anthocyanins compared with those dried at 110 ℃. [Conclusion] Drying at low temperatures and appropriately shortening the initial gelatinization stage below 90 ℃ is conducive to the retention and extraction of anthocyanins from purple sweet potatoes.

利用Hot Potatoes设计大学英语多媒体作业

Hot Potatoes是一种易学好用的语言教学辅助工具。文章中介绍了其常用的功能及在设计大学英语多媒体作业方面的应用优势,并用图示以听力理解题型和匹配型练习题为实例,详细介绍使用Hot Potatoes设计出符合英语教师教学实际需要的多媒体作业的操作步骤。

Hot Potatoes交互式网络教学软件的应用

Hot Potatoes是专门用来制作互动式测验练习的软件,它无需编程,只要输入文本便可以制作出Web页面的交互式测验练习,适用于学生自学及练习之用.本文作者根据个人在制作Hot Potatoes课件的实践经验,介绍该交互式练习软件的特性、制作及其应用.

利用Hot Potatoes轻松制作英语网考模拟题

新的教学模式以现代信息技术为支撑,特别是网络技术,使英语教学朝着个性化学习、不受时间和地点限制的学习、主动式学习方向发展。通过使用Hot Potatoes制作英语听力选择题和复合式听写、阅读理解题的方法,能够帮助学生适应新的四六级网考评估模式。

Hot Potatoes在英语练习与测试中的应用

本文介绍了web交互式练习题软件Hot Potatoes及其主要功能特点,然后详细介绍了使用Hot Potatoes制作英语单项选择题、阅读理解题的方法,以及如何通过The masher把各种类型的题目组合起来。

Determination of Trace Elements in Potatoes by Flame Atomic Absorption Spectrometry

[Objective] This study aimed to analyze the contents of trace elements in potatoes from different production areas in Qinghai Province. [Method] By flame atomic absorption spectrometry （FAAS）, the contents of various trace elements in potatoes were determined. [Result] Potatoes contain abundant trace elements such as Cu, Zn, Fe, Mn, Ca, K and Mg. To be specific, the contents of Ca, K and Mg were relatively high. [Conclusion] By using FAAS, the relative standard deviation was 1.17%-2.75% and the recovery rate was 97%-99.5%, indicating accurate and reli-able results with high precision.

Nutritional evaluation of different cultivars of potatoes(Solanum tuberosum L.) from China by grey relational analysis(GRA) and its application in potato steamed bread making

Chemical composition(moisture,protein,starch,ash,fiber,fat),vitamins(vitamin C,vitamin B1,vitamin B2),total polyphenol content,antioxidant capacity,minerals,and amino acid of 14 potato cultivars in China were evaluated.The results indicated that all parameters varied significantly among different potato cultivars.The total starch,crude protein and fat content ranged between 57.42–67.83%,10.88–14.10% and 0.10–0.73% dry weight(DW),respectively.Moreover,the consumption of potato increased remarkably the dietary intake of vitamins,K,Mn and Cu.In addition,the chemical score of amino acid varied considerably between different cultivars,which ranged from 54(Neida 3 and Neida 41) to 71(Neida 34).Grey relational analysis(GRA) indicated that Neida 26 exhibited the most comprehensive nutritional values among potato cultivars,followed by Neida 42.Different potato flours had a significant effect on the quality parameters of potato steamed bread(PSB),Neida 26 and Neida 34 were more suitable for making PSB.

Inhibitory effect of tartary buckwheat seedling extracts and associated flavonoid compounds on the polyphenol oxidase activity in potatoes(Solanum tuberosum L.)

To improve the processing quality of potatoes,phosphate buffer extract(PBE),50%ethanol(E50),and aqueous extract(AE)of tartary buckwheat seedlings were evaluated for their ability to inhibit the enzymatic browning of potatoes.The results suggest that all extracts of tartary buckwheat seedlings exert significant inhibitory effects on the polyphenol oxidase(PPO)activity in potatoes.The relative concentrations required for a 50%reduction in the PPO activity(IC50)were 0.21,0.28 and 0.41 mg mL^-1,for PBE,E50 and AE,respectively.The strongest inhibitory activity was observed for PBE,followed by E50 and AE.Four flavone compounds in the PBE of tartary buckwheat seedlings(i.e.,rutin,kaempferol-3-O-rutinoside,quercetin,and kaempferol)were identified by high-performance liquid chromatography.These compounds were subsequently evaluated for their roles in the inhibition of PPO from potatoes using a model system.The results indicated that rutin exhibited the highest inhibition rate on the PPO of potato.A synergistic inhibitory effect was observed by mixing rutin,kaempferol-3-Orutinoside,quercetin,and proteins.The inhibitory patterns of rutin,kaempferol-3-O-rutinoside,and quercetin on the enzyme were noncompetitive and reversible,with inhibitory constants of 0.12,0.31,and 0.40 mg mL^-1,respectively.Flavonoids from tartary buckwheat seedlings may exhibit a common mechanism with phenolic compounds,involving the blockage of the reaction of oxygen with PPO leading to the inhibition of the enzymes involved in browning.Based on these results,extracts of tartary buckwheat seedlings can be used as potent natural inhibitors.

Effects of Drying Processes on the Antioxidant Properties in Sweet Potatoes

The effects of different drying methods （hot-air drying, microwave drying and vacuum-freeze drying） on the antioxidant activity and antioxidants in sweet potato （lpomoea batatas L. Lain.） tubers were investigated to determine the potential drying process. Sweet potato tubers were cut into 5 mm thick slices, steamed at 100℃ for 10 rain, then dried in either hotair, microwave, or vacuum-freeze. The dried sweet potatoes in microwave possessed the highest antioxidant activity, while the lowest activity was observed in hot-air dried samples. The phenolic contents were positively correlated with scavenging activity and reducing power of DPPH^＋. The microwave drying retains the highest antioxidant activity with the highest content of phenolic compounds in dried sweet potatoes. β-carotene and ascorbic acid showed minor contribution to the antioxidant activity in dried sweet potatoes.

Nitrogen Nutrition Index and Its Relationship with N Use Efficiency, Tuber Yield, Radiation Use Effi ciency, and Leaf Parameters in Potatoes

Knowledge about crop growth processes in relation to N limitation is necessary to optimize N management in farming system. Plant-based diagnostic method, for instance nitrogen nutrition index （NNI） were used to determine the crop nitrogen status. This study determines the relationship of NNI with agronomic nitrogen use efficiency （AEN）, tuber yield, radiation use efficiency （RUE） and leaf parameters including leaf area index （LAI）, areal leaf N content （NJ and leaf N concentration （N0. Potatoes were grown in field at three N levels： no N （N 1）, 150 kg N ha^-1 （N2）, 300 kg N ha^-1 （N3）. N deficiency was quantified by NNI and RUE was generally calculated by estimating of the light absorbance on leaf area. NNI was used to evaluate the N effect on tuber yield, RUE, LAI, NAL, and NL. The results showed that NNI was negatively correlated with AEN, N deficiencies （NNI〈 1） which occurred for N 1 and N2 significantly reduced LAI, NL and tuber yield; whereas the N deficiencies had a relative small effect on NAL and RUE. To remove any effect other than N on these parameters, the actual ratio to maximum values were calculated for each developmental linear relationships were obtained between NNI and tuber RUE to NNI. stage of potatoes. When the NNI ranged from 0.4 to 1, positive yield, LAI, NL, while a nonlinear regression fitted the response of

Sensory Evaluation of Pigmented Flesh Potatoes (<i>Solanum tuberosum</i>L.)

Pigmented potato cultivars were ranked by a consumer panel for overall acceptance, and acceptance of aroma, appearance, and flavor. Potatoes were analyzed for total phenolics, anthocyanins and carotenoids. Concentrations of total phenolics in yellow and purple potato cultivars were 2-fold greater (P P

The Effect of Plant Growth Regulator and Active Charcoal on the Development of Microtubers of Potatoes

With the detoxicated seedling of a potato cultivation breed named “Mire” as the material, the effect of auxins CCC, 6-BA, and active carbon to microtubers of potato (Solanum tubersum L.) was investigated under the in-vitro circumstances. The result indicated the exogenous auxins improved the production and quality of microtubers of potatoes. The effect of induction can be described as CCC > CCC + 6-BA > 6-BA > CK, the number of microtubers in per flask is 8.17 > 7.67 > 7.29 > 5.46, and the number of large potatoes in per flask is 6.33 > 5.17 > 3.17 > 1. In addition, by adding 0.5‰ of active charcoal, the growth period was shortened from 25.0 days to 9.33 days on average, and the amount of larger potatoes increased 8.54%. These results benefited the growth of microtubers of potato.

Integrated pest management of potatoes

The potato (Solanum tuberosum L.) is the most important dicotyledonous source of human food. It ranks fifth major food crop of the world, exceed only by the grasses such as wheat, rice, maize, and barley. It is characteristically a crop of the cool, temperate regions or of elevation of approximately 2,000 m or more in the tropics. It requires cool nights and well drained soil with adequate moisture and does not produce well in low altitude, warm, tropical environment. Commercial production of most potatoes is primarily through vegetative propagation by means of lateral buds formed on the tuber, a modified stem. Trough such vegetative propagation, many diseases are transmitted from generation to generation. Suppression of such diseases and reduction of yield losses due to disease are a necessary part of increasing the food supply. The principles, strategies, and tactics of plant disease management are important to preventing yield losses. Integrated pest management (IPM) may supply effective control of the potato pests including aphids (vector of some viruses), Verticillium wilt blackleg, bacterial ring rot, Rhizoctonia, Phytophthora infestans (late blight) and several weeds (night shades, pigweeds, lambs quarters, and annual grasses). It includes regular inspection for healthy seed or nursery, crop production, correct identification of the problem, cultural practices (crop rotation, sanitation etc.), biological control, soil fumigation (if necessary), seed or nursery stock treatment and disinfestations of cutting tools. In this review, pest management methods of potatoes included in IPM was summarized.

基于Hot Potatoes的网络交互式学习趋势研究

随着我教育事业的蓬勃发展,未来教育呈现出网络化、多元化和数字化的特点。Hot Potatoes作为一款专门用来制作交互式网络教学练习题的软件,为网络交互式学习提供了方便。概括了Hot Potatoes和交互式学习的概念及特点,论述了将Hot Potatoes应用于交互式学习中的优势。

Influences of Different Distances between Ridges or Plants on Yield of Sweet Potatoes

Based on the combination test of various distances between ridges or plants, the influences of corresponding cultivation techniques on the per unit area yield of a variety of sweet potatoes Xushu 22 in Xianning City were analyzed. The results show that different distances between ridges or plants had significant effects on the per unit area yield of Xushu 22; when the distances between ridges and plants for Xushu 22 planted in the city were 80 and 21 cm respectively, the per u- nit area yield of Xushu 22 was the highest, up to 48 340.7 kg/hm2.

Effect of Cooking and Reconstitution Methods on the Loss of Bioactive Compounds in Pigmented and Unpigmented Potatoes

Total phenolics, anthocyanins and antioxidant capacity of five coloured/pigmented (AR2009-10, Adirondack Red, Adirondack Blue, Congo, and POROIPG22-1) and two unpigmented potato genotypes (“Anuschka” and “Russet Burbank”) were assessed in fresh (with and without skin) and commercially processed/cooked/reconstituted products. Ascorbate profiles of the seven genotypes also were investigated using fresh tuber/tissue only. The results showed that genotypes greatly varied in their contents of bioactive compounds. Ascorbate profiles of the genotypes were not associated to any particular flesh colour/pigment. However, the pigmented potatoes had 1.5 to 2.5 times more the phenolics, 2 to 3 times more antioxidant capacity and higher levels of anthocyanins (13.98 to 38.57 mg C3GE-100g FW) compared to unpigmented genotypes. No anthocyanins were detected in the unpigmented potatoes. Significant losses of total phenolics, anthocyanins and total antioxidant capacity were found during peeling (18% - 23%), blanching process (40% - 60%) and further cooking/ reconstitution (7% - 12%) with no prominent genotype differences. Together, 65 to 90% of these bioactive compounds were lost during processing. The results suggested that pigmented potatoes contained higher amounts of total phenolics and anthocyanins and blanching step took away the most of the original bioactive compounds.