PECTIN METHYLESTERASE ACTIVITY AND THE TEXTURE OF CARROT SLICES COOKED IN AN ELECTRIC CASSEROLE*

Carrot slices cooked for 11 hours on the LOW setting of an electric casserole were firmer and less acceptable than those which had been boiled for 25 minutes; when slices were cooked on the HIGH setting of the casserole for 6 hours they became as soft as boiled slices. Short periods of heat treatment in the casserole on LOW, followed by boiling for 25 minutes, produced slices which were firmer and less acceptable than those which had simply been boiled. These observations may be explained in terms of the action of the enzyme pectin methylesterase (PME) which at certain temperatures can cause firming of plant tissue. During the early stages of casserole treatment on LOW, considerable PME activity could be detected in carrot slices whereas on the HIGH setting, thermal inactivation was more rapid. When using the casserole on LOW, undesirable firmness in carrot tissue could be prevented by subjecting slices 1 cm thick to a preliminary 2 minute blanch in boiling water.     

不同加工工艺对速冻毛豆中毒死蜱残留量的影响

采用气相色谱法,测定了不同加工工艺对速冻毛豆中的毒死蜱残留量的影响。结果表明,各种加工工艺对速冻毛豆中的毒死蜱残留都有不同程度的去除作用。热烫时间越长,毒死蜱残留量越低,98℃热烫180s后,残留下降43.7%;相同时间内,清水浸泡洗涤的去除率为47.0%,15%盐水浸泡洗涤的去除率为81.1%;固定浓度O3处理时间越长,毒死蜱残留量越低,相同时间内,浓度越高的O3处理,毒死蜱的去除率越高,经5mg/kgO3处理30min,去除率为40.3%;H2O2处理也具有与O3处理相同的作用,经3.0mL/LH2O2作用30min,去除率为57.3%。结果显示,适当延长加工工艺中的热烫时间,或采用盐水浸泡的生产工艺,或是采用O3或H2O2处理的生产工艺,均能有效降低速冻毛豆中毒死蜱的残留量。     

饮用水中亚硝酸盐的测定与分析

亚硝酸盐与人们的生产生活及个体健康息息相关。本文测定了市售的5种品牌的饮用水中开启不同时间的亚硝酸盐含量并研究了煮沸后放置不同时间、煮沸次数对自来水中亚硝酸盐含量的影响。结果表明,5种品牌的饮用水在刚开启时和开启当天均未检出亚硝酸盐,隔夜和1周后亚硝酸盐含量增高;自来水煮沸后放置时间越长,亚硝酸盐含量越高,煮沸次数越多,亚硝酸盐喊来那个越高。     

预处理技术对马铃薯原料及油炸马铃薯脆片品质影响的研究

为改善马铃薯脆片品质,本文分析了漂烫、浸渍、冷冻等预处理技术对马铃薯原料(主要是营养成分维生素C含量)和油炸马铃薯脆片品质的影响。结果表明,马铃薯切片厚度2 mm,采用漂烫(95℃漂烫2 min)、浸渍、冷冻相结合的方式可较好保存维生素C,又可得到感官评定最佳的油炸马铃薯脆片。     

THE DIFFUSION OF SALT INTO POTATOES DURING BOILING AND CONSUMER PREFERENCES FOR VARIOUS FINAL SALT CONCENTRATIONS

This paper describes an investigation of the diffusion of salt into potatoes, which are boiled in salt water, and the perception by and preferences of the consumer for various final salt concentrations. Potatoes were cooked in boiling salted water and tested by untrained taste panels. It was established that:

• 1 Salt only penetrates the outermost layers of the potato during cooking.
• 2 Despite this fact the cooked potato is perceived as ‘salted’.
• 3 Mashing the potatoes gives a final internal salt concentration of about 0.05 M.
• 4 The internal salt concentration preferred by most people is 0.1–0.15 M.

     

不同因素对甘薯呼吸强度影响

甘薯是我国四大主要粮食作物之一,具有丰富的营养价值.呼吸作用是农产品收获后进行的重要生理活动,是影响贮运效果的重要因素.测定呼吸强度可衡量呼吸作用强弱,了解农产品收获后生理状态,为低温和气调贮运以及呼吸热计算提供必要数据.可利用0.5%黄酮液浸泡3h的方法抑制甘薯呼吸作用,延长甘薯贮藏期.冷藏会刺激甘薯呼吸增强,但最终会达到一个稳定呼吸状态.大个甘薯的呼吸强度明显要弱与小个甘薯,大个甘薯呼吸强度为小个甘薯的73.6%.     

马铃薯淀粉废水处理技术研究

马铃薯淀粉生产过程中,要排放大量的废水,平均每生产1t淀粉需要加工6.5t左右的马铃薯,排放20t左右的废水。综述了马铃薯淀粉生产废水的来源、水质特性及处理技术。     

Impacts of Generic and Brand Advertising in the U.S. Potato Market

Abstract

The impacts of generic and branded advertising in the U.S. fresh potato, retail frozen potato, and potato chip markets are examined under exogenous and endogenous raw potato supply. The Almost Ideal Demand System is used to estimate the demand components. The general equilibrium elasticities derived from the complete model are used in a simulation analysis to assess the cross-commodity effects of incremental increases in advertising expenditures on equilibrium prices, quantities, revenues, and profits in each sector. The endogeneity of grower supply mitigate the impacts of advertising in the raw commodity sector and in the retail sectors.     

微波辅助催化合成尿囊素的研究

以—水乙醛酸和尿素为原料，对甲基苯磺酸—磷酸构成的复合酸作为催化剂，利用微波辅助加热技术，经环化缩合反应制备了医药和有机合成中间体及日化助剂尿囊素。研究表明，微波辅助加热可以有效地提高反应效率，反应中的微波辐射功率以500-700W为宜；在微波辐射功率为650W时，微波加热反应15min后尿囊素收率可达60％左右，结果相当于普通加热方式加热反应6h的效果。产品经元素分析、熔点测定、红外光谱表征并用滴定法测定其纯度，尿囊素含量在98％以上。     

乙醇浸提法提取红薯茎叶总黄酮的研究

采用乙醇浸提法提取红薯茎叶中的黄酮,在前期单因素研究基础上,进行正交设计试验,得出乙醇浸提法提取红薯茎叶中黄酮的最佳工艺条件:乙醇浓度80%、提取时间3 h、提取温度70℃、料液比1∶40,在该条件下黄酮的提取率为0.831 6%。     

谷物冷却机对东北粳稻的安全度夏储粮试验

东北粳稻谷冷通风的储粮试验的结果表明,在南方高温高湿天气下,采用谷冷准低温储粮,可消除常规储藏粮堆的发热隐患,避免储粮的晾晒及熏蒸,有利于稻谷品质保鲜,与常规储藏相比,谷冷通风储粮的吨粮成本可降低约12.67元,粮库粳稻储存经济效益和社会效益显著。     

浅谈高大平房仓粮食发热的预防与处理

粮食发热现象是保管过程中普遍存在的问题。为减少发热现象带来的危害,应认真对待以下3个问题：①找出粮食发热现象的9个方面的原因,为预防及发热后的处理提供依据。②在保管过程中,预防在先,采用9种有效措施防止发热现象的发生。③粮食已出现发热现象,就必须根据产生发热的不同原因,分别进行通风、降温、降水、杀虫、翻仓等手段进行及时处理,减少粮食损失。     

Slicing,Dicing, Spicing,and Pricing: Factors Influencing Purchase and Consumption of Fresh Potatoes

To better understand potential reasons for a North American decline in fresh potato consumption, a region-wide survey (n = 1009) was undertaken in eastern Canada. Results were examined comparing high- and low-frequency potato users on a variety of factors, including beliefs, attitudes, barriers, needs, and satisfaction with potatoes. Respondents indicated positive perceptions pertaining to potato nutrition, taste, preparation, and overall enjoyment. Multiple logistic regression analysis suggested two variables—age and the perceived importance of potatoes for the everyday meal—were strong predictors of high versus low frequency of potato consumption. Respondents judged the ability to see the potato in the package, potato firmness, and locally produced as point-of-purchase characteristics particularly important when buying fresh potatoes. However, respondents also indicated that their needs were not fully met and expressed relatively low levels of satisfaction when purchasing potatoes. Based on the results, suggestions are provided for improving the marketing of fresh potatoes.     

土豆困境

<正>随着天气渐渐变冷,我国北方马铃薯主产区——内蒙古自治区的许多薯农心急如焚。今年,内蒙古马铃薯不仅价格低迷,而且滞销卖难。为减少农民损失,国家和内蒙古已出台多项措施,力抓马铃薯销售、加工和储藏工作。一方有难,八方支援。内蒙古马铃     

The effects of liquid honey as a partial substitute for sugar on the physical and sensory qualities of a fat-reduced muffin

This study investigated the effect of liquid honey as a partial substitute for sugar on the baking and keeping qualities of a fat-reduced muffin. In the formulation, the fat-reduced muffin used a hydrocolloid fat replacer, bacterial and fungal amylases and an emulsifier (DATEM). Honey caused a significant (P0.05) increase in crust and crumb colour at all replacement levels; however, the use of honey at the 25% replacement level was favourably increased the crust colour in the fat-reduced formulation. The addition of honey increased moisture content and decreased water activity, but did not decrease firmness or the staling rate, especially after prolonged frozen storage. Sensory results indicated that honey increased cohesiveness and decreased tenderness in the muffin. The added moisture in the fat-reduced muffin did not improve the perceived moistness, as indicated by the results.     

基于LabVIEW的微波网络分析仪功能扩展与自动测量

基于LabVIEW集成开发环境,通过GPIB接口建立了微波网络分析仪与PC机间的通信,并在PC机上开发了虚拟微波网络分析仪程序。该程序扩展了原仪器的测量通道,置换并升级了数据存储方式和类型,同时很方便地利用HP8510B网络分析仪实现了自动测量。     

An Economic Analysis of Requirements to Prevent Handheld Hair Dryer Water Immersion Electrocutions in the USA

Before 1987, when handheld hair dryers were not required to protect against water immersion electrocutions, there were almost 16 such electrocutions annually in the USA. This article presents a retrospective evaluation of the benefits and costs of the 1987 and 1991 immersion protection requirements of the voluntary hair dryer safety standard in the USA. The benefits are based on estimates of the reduced risk of electrocution resulting from the requirements, and the valuation of the reduced risk derived from willingness to pay studies of the “value of statistical life” found in the economics literature. The costs were defined as the incremental costs associated with incorporating the immersion protection technology into handheld hair dryers. The study found that the requirements were highly effective and may have reduced the immersion-related mortality rate by almost 97%. The expected present value of the estimated benefits of the requirements amounted to about $4.56 per dryer in 2014 dollars and substantially exceeded the costs of about $2 per dryer. The primary outcome measure, the expected net benefits (i.e., benefits minus costs) of the requirements, amounted to an average of about $2.56 per hair dryer, over the hair dryer’s expected product life. Given sales of about 23 million handheld hair dryers annually, the present value of the expected net benefits associated with 1 year’s production would have amounted to about $58.9 million. A sensitivity analysis showed that the major findings were robust with respect to changes in the underlying parameters of the analysis. The study also discusses the factors leading to a high rate of effectiveness estimated for the immersion protection requirements.     

马铃薯全粉蛋糕工艺优化研究

本实验以马铃薯全粉、白砂糖、鸡蛋的添加量为变量,通过单因素实验和正交实验确定了马铃薯全粉蛋糕最佳配方,即马铃薯全粉100 g,水50 g,盐1 g,油50 g,糖60 g和鸡蛋180 g。马铃薯全粉蛋糕色泽更佳,口感更好,营养价值更高,且具有突出的马铃薯风味。     

基于流通环节的黑龙江省马铃薯产业现状与发展对策

目前,在交通运输和信息基础设施等方面,黑龙江省具备了发展农产品物流的基础条件,黑龙江省的马铃薯加工企业和市场体系建设取得了一定发展。但是,黑龙江省的马铃薯产业在流通环节也面临一些亟待的问题,尤其是在贮藏和运输设施、批发市场和集贸市场、流通组织,市场信息网络建设、品牌建设,行业标准与法规建设等方面急待加快发展。     

我国冷链物流能耗现状及对策研究

冷链物流是冷冻工业和物流相结合的低温供应链系统,在冷藏运输、冷藏储存、冷链连接点和其他辅助活动环节都会造成一定的能源消耗,而相关的技术、管理、设备设施、冷库布局等都是影响能耗的因素,我国应该统筹规划,促进冷链物流的协调发展,加快冷链物流能耗标准的制定和法规建设,鼓励企业采用联盟的运作模式,利用新技术推动能源节约,开展能源利用模式的转换,最终实现冷链物流的能耗节约之目的.