Physicochemical changes occurring during post-harvest hardening of trifoliate yam (Dioscorea dumetorum) tubers

Processing of Dioscorea dumetorum tubers into flour could be a means of adding a longer-term value to this tropical plant with a high nutritional potential but which presents a post-harvest hardening problem. This study was carried out in order to investigate the effect of storage under prevailing tropical ambient conditions (19–28 °C, RH 60–85%) for 56 days on the physicochemical characteristics of flours produced from hardened tubers. With the exception of bulk density, the results showed that all the physicochemical properties measured (water absorption capacity, oil absorption capacity, water solubility index, hydrophilic–lipophilic index, swelling capacity and least gelatinising concentration) were significantly influenced by tuber storage time (P<0.05). In general, the physicochemical indices increased with storage in at least two phases, from days 2 to 21 and from days 28 to 56. Since sprouting of most tubers was observed after 28 days of storage, the results suggest that post-harvest hardening and sprouting influence the above-mentioned indices of flours produced from D. dumetorum tubers.     

Effect of starter culture, spice mix and storage time and temperature on biogenic amine content of dry fermented sausages

Two types of dry fermented sausage differing in spicing mixture and the diameter (low content of red pepper + diameter 80 mm, H-sausage; high content of red pepper + diameter 55 mm, P-sausage, respectively) were produced in parallel with two different starter cultures (Pediococcus pentosaceus + Staphylococcus carnosus, B-samples and S. carnosus + Staphylococcus xylosus + Lactobacillus farciminis, F-samples, respectively). The sausages were ripened 21 days and subsequently stored 91 days at the room temperature. Concentration of both most abundant amines, putrescine and tyramine (y; mg/kg DM) increased significantly (P<0.01) in HB-sausage during ripening (x; days): y=2.5+18.13x−0.3144x² (R²=0.99) and y=0.7+8.17x−0.1130x² (R²=0.99), and also during storage: y=127.3+5.123x (R²=0.79) and y=26.0+3.211x (R²=0.74), respectively. At the end of ripening, putrescine (247 mg/kg DM) and tyramine (123 mg/kg DM) content in the HB-sausage was higher (P<0.05) than in the PB-sausage (12 and 9 mg/kg DM, respectively), concentration of either of these amines was negligible (1 mg/kg DM) in either type of F-inoculated sausage. Both starter culture and sausage type influenced significantly (P<0.001) both putrescine and tyramine content in the sausage; starter accounted for 57% and 55% of total variability in putrescine and tyramine content, respectively. Due to the significant (P<0.05) increase of total aerobic counts in the HB-sausage between the end of ripening and the 7th day of storage, followed by the significant (P<0.01) increase of the sum of total biogenic amines between the end of ripening (425 mg/kg DM) and the end of storage (1029 mg/kg DM), the storage of the dry fermented sausages at the room temperature should not be recommended.     

Computational Shelf-Life Dating: Complex Systems Approaches to Food Quality and Safety

Shelf-life is defined as the time that a product is acceptable and meets the consumers expectations regarding food quality. It is the result of the conjunction of all services in production, distribution, and consumption. Shelf-life dating is one of the most difficult tasks in food engineering. Market pressure has lead to the implementation of shelf-life by sensory analyses, which may not reflect the full quality spectra. Moreover, traditional methods for shelf-life dating and small-scale distribution chain tests cannot reproduce in a laboratory the real conditions of storage, distribution, and consumption on food quality. Today, food engineers are facing the challenges to monitor, diagnose, and control the quality and safety of food products. The advent of nanotechnology, multivariate sensors, information systems, and complex systems will revolutionize the way we manage, distribute, and consume foods. The informed consumer demands foods, under the legal standards, at low cost, high standards of nutritional, sensory, and health benefits. To accommodate the new paradigms, we herein present a critical review of shelf-life dating approaches with special emphasis in computational systems and future trends on complex systems methodologies applied to the prediction of food quality and safety.     

广蓄电厂下库碾压混凝土重力坝安全运行管理

广州蓄能水电厂下库大坝为碾压混凝土重力坝,自1992年4月下闸蓄水以来,已安全运行了14年。2002年4月顺利通过了首次大坝安全定期检查,被评为正常坝。本文主要介绍广州蓄能水电厂下库大坝在安全运行管理的一些实践和经验。     

日本稀土贮氢电池现状和发展趋势

本文论述了日本稀土贮氢电池的生产现状、市场分析和发展趋势。     

一种辊压式锌电极湿贮存特性

本文介绍了用PTFE作粘结剂的辊压式锌电极。它不仅具有优异的机械强度,而且又有很好的电化学活性,可以在500mA/cm~2高电流密度下进行放电,同时还具有耐湿贮存的特性。     

表面改性对贮氢合金电极性能的影响

本文用化学处理和化学镀镍对金属氢化物的表面改性处理,初步讨论和分析了这些处理对金属氢化物电极的活化和容量等性能的影响。其结果表明:表面改性后的贮氢电极放电容量提高,放电特性增强。     

贮氢合金组成对电极性能的影响

本文研究了混合稀土MmBx贮氢合金B组分的钴含量和Mm(Ni_(0.70)Co_(0.16)Mn_(0.08)Al_(0.06))_x的配比数x对P-C-T曲线平衡氢压、放电容量和电池的循环使用寿命的影响。     

电化学电容器的研究进展--第15届国际电化学电容器研讨会概述

介绍了第15届国际电化学电容器研讨会有关电化学电容器的研究发展情况;分析了电化学电容器的研究发展趋势。研究热点是高性能新型炭电极材料的制备研究、器件的性能和应用研究以及电化学混合电容器新体系的研究等。     

考虑源网荷储协调互动的配电网无功优化

无功电压控制是保障电网安全稳定运行的基础,高比例新能源发电是新型电力系统的主要特征,挖掘新能源发电、储能以及柔性负荷等柔性可控资源的无功电压潜力能有效保障新型电力系统安全稳定运行。文中提出了一种考虑源网荷储互动的配电网无功电压控制方法,从负荷需求侧响应出发基于市场实时电价信息以负荷转移成本和用户购电成本为基础实现价格驱动需求响应的负荷平移策略;利用储能系统协调新能源发电出力和负荷平移规则,构建综合考虑源网荷储互动的配电网无功优化模型。通过调节无功补偿设备、储能充放电策略协调新能源出力,在满足负荷需求侧响应需求的基础上达到系统无功电压的最优控制。通过改进的IEEE33节点系统仿真分析,实验结果表明通过源网荷储的充分互动能够有效提高系统无功电压调节能力,实现配电网安全、经济运行。