红茶中茶多酚提取工艺的研究

以红茶茶叶为原料,考察了浸提温度、时间、固液比、pH对茶多酚提取的影响,并对其浸提率进行了研究.结合正交试验,确定了红茶茶叶提取的最佳工艺条件.     

感官量化描述分析(QDA)优选烧烤酱料工艺参数的研究

文章运用感官定量描述分析(QDA)进行定性和定量结合的分析检验方法,对烧烤酱料进行评鉴和参数优选实验研究.结果表明:QDA法可以有效简便地优先配方和工艺参数,风味酶酶解酱料的感官QDA评分最高,复配酶酶解酱料的QDA最高平均分仅比单用木瓜蛋白酶酶解产物高2.5分.该方法简便可行,对酶解烧烤酱料不建议使用风味酶和其它蛋白酶复配的方式.     

墨囊多酚氧化酶在红茶加工中的应用研究

为了研究经提取并纯化后的墨鱼墨中多酚氧化酶(PPO)的酶活性及其在红茶饮料加工中的应用,以新鲜墨鱼墨囊为PPO提取原料,用p H7.2磷酸盐缓冲液初步提纯,粗酶液又经饱和度为30%-80%硫酸铵分级沉淀,得到纯化倍数为3.09,酶活性达到199450u的PPO粗酶液。为探寻墨囊PPO在红茶饮料加工中的最佳工艺方案,通过单因素实验和正交试验以及感官评定试验,确定其在红茶饮料加工中应用的最佳工艺条件为:酶添加量为0.05%(m/v),反应温度为50℃,反应体系pH为8.0。     

辣根过氧化物酶活性检测方法研究

通过单因素实验和正交实验研究了辣根过氧化酶(HRP)活性测定条件:缓冲溶液种类、缓冲溶液离子浓度、pH值、温度对其影响.实验结果表明在25℃下,0.1mol/L,pH=7.0的磷酸盐缓冲溶液中反应,辣根过氧化物酶的酶活力达到最大值1.13×107 U/g;确定辣根过氧化物酶活性的最佳检测方法:1mg HRP溶解于1mL 0.1mol/L磷酸盐缓冲溶液(pH=7.0),反应温度为25℃,检测波长为436nm.该方法简单可靠,操作简便,可有效应用于实验室和常规生化检测.     

超声波辅助提取南瓜色素的工艺研究

通过单因素试验和正交试验,考察超声波提取南瓜色素的工艺参数和提取效果,实验结果表明超声波提取南瓜色素的最佳工艺条件为：提取温度70℃,料液比25：1,超声时间35min,超声功率300W。     

鱼蛋白肽的制备及其作为功能食品基料的应用

鱼蛋白肽可由鱼及其加工副产物的蛋白水解而成,其原材料来源广泛,成本低廉.鱼蛋白肽具有易吸收,氨基酸比例均衡,属优质蛋白资源,且还具有抗氧化、增强免疫、降血脂等多种生物活性,已越来越受到关注.文章综述了鱼蛋白肽的制备方法、氨基酸组成及其作为功能食品基料的应用情况,旨在为鱼蛋白肽的深入研究与产业化应用提供参考.     

罗汉果有效成分提取工艺的研究

罗汉果是广西特产，罗汉果属植物的果实。在单因素实验的基础上，利用微波萃取系统，进行二次回归旋转正交组合实验，确定了微波辐射条件下不同的物理参数（辐射功率、辐射时间、溶剂量等）对提取率的影响，优化的微波辅助提取最适工艺条件是：乙醇浓度40％；微波辐射功率495W；辐射时间6min；提取压力0．1MPa；原料粉碎度100目；固液比1：30。在此条件下，罗汉果皂苷一次提取率可达76％。     

凝固型大米风味酸奶的研制

用大米蛋白或大米蛋白水解物部分替代牛乳粉生产大米风味酸奶,以谷糠乳杆菌和乳酸乳球菌乳酸亚种为发酵菌种,以酸度和感官为评价指标,通过大米蛋白及其水解物添加量、大米蛋白水解度、乳糖补加及蔗糖添加研究对大米风味酸奶酸度和感官的影响。结果表明,大米风味酸奶的酸度和感官评分随大米蛋白添加量的增加而降低。产品酸度随大米蛋白水解度增加而增大,大米蛋白水解度为7.5%时感官得分最高;产品酸度和感官评分随大米水解物添加量增加而降低,大米蛋白水解物添加量在40%以下时,均可生产出合格的大米风味酸奶。补加乳糖对产品酸度和感官无显著影响。添加蔗糖对产品酸度无显著影响,但对产品感官影响显著,蔗糖添加量在4~6%时,大米风味酸奶的感官得分最高,表现为色泽均匀,质地较细腻,未见乳清析出,凝乳稳定,口感较细腻柔滑,酸甜度适中,米香风味浓郁。     

微波辅助法提取橙皮苷工艺研究

采用微波辅助法提取脐橙皮渣中的橙皮苷,研究不同溶剂对脐橙皮渣中橙皮苷提取率影响,筛选利于橙皮苷提取的溶剂。在单因素试验基础上,设计影响橙皮苷提取效果的微波辅助提取正交试验。实验结果表明,影响橙皮苷提取的最佳提取组合:微波功率为低火档,料液比为1:40,微波时间为20s,此工艺条件下用HPLC测得橙皮苷的提取率为2.23%。     

复配南极冰鱼短肽保鲜剂对鱼糜品质的影响研究

以南极冰鱼为原料制备短肽,进行复配添加到新鲜罗非鱼鱼糜中,评价新型保鲜剂对一定贮藏期内鱼糜品质的影响.结果表明:通过Ca2+-ATPase活性、TBA值、鱼糜凝胶强度和颜色为指标,优选出南极冰鱼酶解物、魔芋葡甘露聚糖、马铃薯纤维3种保鲜剂较佳用量范围.优化复配工艺,得到魔芋葡甘露聚糖3%、南极冰鱼酶解物0.4%、马铃薯纤维2%的保鲜效果最好.这种鱼糜保鲜剂可有效抑制鱼糜中蛋白变性及脂肪氧化,且具有含糖量低、热量低等特点.     

Designing flavors for mass consumption

Abstract

In the increasingly competitive market for processed foods after the Second World War, flavor assumed new importance in product design and development as companies struggled to gain advantage and entice repeat buyers. This paper examines the flavor profile, a novel sensory evaluation method developed by chemists at Arthur D. Little, Inc. (ADL), the storied Cambridge, MA consulting firm. Introduced in 1949, the flavor profile claimed to offer a reliable way of measuring and describing the subjective sensory qualities of products. Drawing extensively on archival material, I document the circumstances surrounding the development of the flavor profile at ADL, examine its uses, and consider the conditions that led to its widespread adoption by the food industry. By considering the flavor profile as both a scientific instrument for flavor measurement, and a practical tool for flavor design and development, I hope to illuminate a dark corner in the history of food industrialization: the values, ideologies, and contingencies that shaped how foods were made to taste in the postwar period.     

The ratio bias phenomenon: fact or artifact?

The ratio bias—according to which individuals prefer to bet on probabilities expressed as a ratio of large numbers to normatively equivalent or superior probabilities expressed as a ratio of small numbers—has recently gained momentum, with researchers especially in health economics emphasizing the policy importance of the phenomenon. Although the bias has been replicated several times, some doubts remain about its economic significance. Our two experiments show that the bias disappears once order effects are excluded, and once salient and dominant incentives are provided. This holds true for both choice and valuation tasks. Also, adding context to the decision problem does not alter this finding. No ratio bias could be found in between-subject tests either, which leads us to the conclusion that the policy relevance of the phenomenon is doubtful at best.     

Learning Style Preferences of Persons with Narcolepsy

SUMMARY

The entry of Levodopa into the brain is limited by competition with large neutral amino acids (LNAA). A strict low protein diet improves motor fluctuations but might lead to protein malnutrition. Because insulin secretion lowers plasma LNAA, a stable dietary ratio of carbohydrate:protein might be as effective as protein restriction. This double blind crossover study compared the effects of three proportioned diets: (A) a 7:1 carbohydrate: protein ratio; (B) a 30:1 carbohydrate: protein ratio; and (C) a 1:1.5 carbohydrate:protein ratio, on motor fluctuations, plasma LNAA and levodopa in 12 Parkinson patients. After random assignments to each diet, patients were observed for 11 hours. Serum levodopa and LNAA levels and motor component of the UPDRS were measured hourly. The 7:1 and high carbohydrate diets were both effective at stabilizing plasma LNAA levels. Mean hourly sum of LNAA was significantly different on each of the diets, being highest on the high protein diet and lowest on the high carbohydrate diet. There was a significant correlation between plasma LNAA and amount of “off” time, and a significant inverse correlation between plasma LNAA and amount of time “on with dyskinesias.” A fixed dietary carbohydrate:protein ratio stabilizes plasma LNAA levels and may optimize response to levodopa without the risk of malnutrition.     

中草药复方A对罗非鱼消化酶活性的影响

以奥尼罗非鱼为试验对象,探讨中药复方A饲料添加剂(主要成分的配方为山楂:麦芽:砂仁=2∶2∶1)对罗非鱼主要消化酶活性的影响。结果显示:中药复方A能极显著地提高鱼体胃和肝胰脏的淀粉酶活性(P<0.01),能显著地提高肠道淀粉酶活性(P<0.05),也能显著甚至极显著地提高胃与肝胰脏中的脂肪酶活性(P<0.05,P<0.01);但对罗非鱼的肠脂肪酶与肠胰蛋白酶的活性无显著作用(P>0.05)。由本实验看出,中草药复方A能一定程度地提高罗非鱼的主要消化酶活性。     

Experts in experiments

An ever increasing number of experiments attempts to elicit risk preferences of a population of interest with the aim of calibrating parameters used in economic models. We are concerned with two types of selection effects, which may affect the external validity of standard experiments: Sampling from a narrowly defined population of students (??experimenter-induced selection??) and self-selection due to non-response or incomplete response of participants in a random sample from a broad population. We find that both types of selection lead to a sample of experts: Participants perform significantly better than the general population, in the sense of fewer violations of revealed preference conditions. Self-selection within a broad population does not seem to matter for average preferences. In contrast, sampling from a student population leads to lower estimates of average risk aversion and loss aversion parameters. Furthermore, it dramatically reduces the amount of heterogeneity in all parameters.     

On the independence of history: experience spill-overs between experiments

A central understanding in experimental economics is that subjects’ decisions in the lab are independent of history. We test whether this assumption of between-experiment independence is indeed justified. We analyze experiments with an allocation decision (like a dictator or ultimatum game) and find that participation in previous experiments tends to increase the amount subjects allocate to themselves. Hence, independence between experiments cannot be presumed if subjects participate repeatedly. The finding has implications for the interpretation of previous allocation decision results and deserves attention when running future experiments.     

论唐代的献诗

在唐代,献诗大略可分为两种,一种具有讽谏性质,另一种则是歌功颂德之作。有官职的人献诗为依例上奏,无官职的人要投匦上奏。人们热衷于献诗,是因为通过献诗可以得官或得到高名。边将献乐往往选取或截取当时著名诗人的诗作作为歌词,其歌词往往具有很高的文学性,而献诗则是诗人一时之作,歌颂之作较多,文学性往往很差。