Effect of short-term storage on phenolic content,o-diphenolase and peroxidase activities of cut yam tubers (Dioscorea sp)

The effect of short-term storage on the protein, phosphorus and phenolic content as well as peroxidase and o-diphenolase activities of cut, harvested Jamaican yam (Dioscorea sp) tubers (D rotundata. D alata and D cayenensis) was studied. There was an initial increase in the total phenolic content up to the third week of storage followed by a gradual decrease to the sixth week. Phenolic content was found to be highest in D cayenensis followed by D rotundata and D alata. The activities of peroxidase (EC 1. 11. 1. 7) and o-diphenolase (EC 1. 10.3.1) increased steadily up to the third week of storage and thereafter decreased to the fifth week. The intensity and rapidity of browning in tubers when cut, correlated very closely with the tuber o-diphenolase and phenolic content levels while the onset of rotting correlated with the peroxidase activity levels in the species studied.     

喷气纺纱质量影响因素探讨

简要分析了半制品质量对喷气纱强力和条干的影响，着重探讨了喷气纺纱机喷嘴压力、牵伸比、集合器宽度等对成纱强力和条干的影响。试验证明，提高半成品的质量、制定适宜的喷气纱工艺是改善成纱强力和条干的关键。     

川中丘陵区一种新型小流域径流输沙模型的建立与应用

径流输沙模型对定量评价水沙的输出响应具有重要的意义。本研究在已有研究成果的基础上，通过对四川盐亭县林山西沟小流域的径流、泥沙进行现场观测与分析，提出含沙量单位线的定义及其确定方法，建立了适应该小流域的径流输沙模型。并应用实测资料进行比较，表明模型的模拟结果可靠，模拟过程确定性系数达0．8以上，为川中丘陵区小流域径流输沙过程的预测预报提供了一个新方法。     

纺速对聚酯工业丝干热收缩率的影响

通过对不同纺速的高粘聚酯初生丝的结构的测试,探讨了初生纤维结构随纺速变化的规律,以及初生丝的结构对成品工业丝的干热收缩率的影响。     

Characterization of yam bean (Pachyrhizus spp.) Seeds as potential sources of high palmitic acid oil

Seeds from 22 accessions of the yam bean species Pachyrhizus ahipa (14 accessions), P. erosus (5), and P. tuberosus (3) were investigated for oil and protein contents, fatty acid composition of the seed oil, and the total tocopherol content and composition. Plants from the accessions were grown under greenhouse conditions during one (P. erosus and P. tuberosus) or two years (P. ahipa). The pattern of the investigated seed quality traits was very similar in the three species. Yam bean seeds were characterized by high oil (from about 20 to 28% in one environment) and protein contents (from about 23 to 34%). Seed oil contained high concentrations of palmitic (from about 25 to 30% of the total fatty acids), oleic (21 to 29%), and linoleic acids (35 to 40%). Levels of linolenic acid were very low, from about 1.0 to 2.5%. Total tocopherol content was relatively low in P. erosus (from 249 to 585 mg kg⁻¹ oil) and P. tuberosus (from 260 to 312 mg kg⁻¹ oil) compared with the levels found in P. ahipa grown under identical conditions (508 to 858 mg kg⁻¹ oil). In all the samples, γ-tocopherol was predominant, accounting for more than 90% of the total tocopherol content. The combination of high oil and protein contents, together with high palmitic acid, low linolenic acid, and high γ-tocopherol concentration, makes these crops an interesting alternative as sources of high palmitic acid oil for the food industry.     

速冻紫薯仔的加工工艺研究

紫薯仔是以紫薯为原料加工而成的方便速食产品,本文将糖、奶油和面粉的添加量3个因素进行正交试验,结果表明,糖的比例对紫薯仔成品品质的影响最大,其次是奶油的比例,面粉在20%以下的比例范围下,对紫薯仔品质的影响最小。     

生草覆盖条件下不同降雨强度对紫色土坡面侵蚀产沙的影响

造林种草,增加植被覆盖度是防止土壤侵蚀的重要措施.通过人工模拟降雨试验,探讨生草覆盖下紫色土坡面侵蚀产沙的动态变化.结果表明,有生草覆盖的坡面径流含沙量较裸地的径流含沙量更快达到稳定状态;坡面侵蚀产沙率随覆盖度增加呈指数型递减,且坡下种草的减沙效果最好;覆盖度与降雨强度对坡面侵蚀产沙量的影响存在对比消长关系,但生草覆盖度对产沙量的影响小于降雨强度的变化对产沙量的影响.     

利川山药淀粉糊化特性研究

利用快速黏度仪（ RVA）研究了pH、食盐、α-淀粉酶及蔗糖对山药淀粉糊化特性的影响,并与马铃薯淀粉、红薯淀粉、玉米淀粉的糊化特性进行比较。结果表明,利川山药淀粉较红薯淀粉、马铃薯淀粉、玉米淀粉更容易老化,热稳定性优于马铃薯淀粉。当pH为5时,山药淀粉的热稳定性与抗老化能力得到改善;食盐使淀粉糊化温度提高;淀粉酶使山药淀粉的峰黏度、谷黏度、终黏度、回生值降低;蔗糖使山药淀粉在高温下的稳定性以及抗老化能力降低。结论：pH、蔗糖、淀粉酶、盐对利川山药淀粉的糊化特性影响较大。     

紫色土丘陵区典型生态-水文单元径流与氮磷输移特征

通过对紫色土丘陵区典型农业-集镇-林地复合型小流域3次降雨-径流全过程的连续监测,测定了径流过程中泥沙含量和不同形态氮磷浓度,以期认识典型农村生态-水文单元降雨径流过程中氮磷迁移规律。结果表明：降雨-径流过程中悬浮泥沙的流失主要集中在径流前期,其峰值出现在雨强最大时;集镇径流污染的影响主要表现在径流前期,是径流前期铵态氮偏高的主因;降雨-径流过程中,颗粒态氮与可溶态氮比（PN/DN）、颗粒态磷与可溶态磷比（PP/DP）的峰值均出现在雨强较大时：其中 PN/DN 多小于1,而 PP/DP 范围为1.1~30.2,说明氮素流失主要通过可溶态的方式,而磷的迁移以颗粒态磷为主。因此在紫色丘陵区建议利用湿地植物与沉砂池等综合措施控制土壤侵蚀和非点源污染以保护当地生态环境安全。     

超声波辅助提取紫甘蓝色素的工艺研究

研究了紫甘蓝色素的提取工艺．以市售紫甘蓝为原料,以超声波辅助提取紫甘蓝色素,考察提取溶剂、液固比、温度、超声波功率、提取时间以及pH等因素对提取效果的影响．通过实验可知：紫甘蓝色素的最佳提取剂为蒸馏水,以超声波辅助提取可明显提高提取率．在以蒸馏水为提取剂的条件下,紫甘蓝色素的最大吸收波长为560nm．以超声波辅助提取时,最适液固比为5：1（mL／g）,提取最适温度为50℃,超声波最适功率为70W,最适提取时间为20min．pH对紫甘蓝色素的影响较大,紫甘蓝色素在不同pH下颜色发生明显变化．