可微波鸡米花预混粉层配料的研究

采用单纯形格子法实验设计优化鸡米花层预混粉的配方,以获得鸡米花微波后表层松脆的口感,通过对鸡米花的脆性、感官指标以及色差的分析,确定预混粉最优的配方为：小麦淀粉21％,变性淀粉25％,蛋清粉2．5％,大豆蛋白4．5％,其他成分占47％。结果表明,采用优化后的预混粉层配方生产出的鸡米花,可以使微波后产品脆性得到显著的提高,而且产品的感官质量较好。     

蔗糖对淀粉物料微波膨化的影响研究

研究了淀粉物料中添加蔗糖后微波加热效果、物料膨化效果的改变情况。结果表明,蔗糖的添加增强了微波对淀粉物料的加热效果,使得物料的温升速率大大提高,且随着蔗糖含量的增加,这种增强效应更明显。由于蔗糖对淀粉糊化的影响及加热后的特性,随着添加量的增加膨化率变小,膨化过程也相对迟缓;随着糖含量的增加,产品的孔隙状态发生变化,孔隙变形、回缩,产品硬度减小,脆度增大,孔隙率渐大,色泽加深。     

The effects of ingredients on popcorn popping characteristics

Response surface methodology was used to evaluate the effects of ingredients on popcorn popping characteristics. The effects of different ingredients on the expansion volume and unpopped kernel ratio of popcorn in a conventional popper and a microwave oven were evaluated and optimized by response surface methodology. The regression models were significant and had R² value in the range of 0.919–0.956. The optimum levels of ingredients for microwave popping were 4.4% salt, 5.9% vegetable oil, 0% sodium bicarbonate and 16.4% butter, this formulation giving an expansion volume of 33.1 mL g^?1. In the case of conventional popping, the maximum expansion volume of 37.3 mL g^?1 was obtained for 3.5% salt, 6% vegetable oil, 0.10% sodium bicarbonate and 12.9% butter.     

碘盐及发酵温度对低盐固态酱油质量的影响

实验室条件下考察了碘盐及发酵温度对低盐固态法酿造酱油的影响。试验分析表明微量碘对酱油的色泽有一定影响,使用碘盐的酱油色率略高于非碘盐的酱油,红色指数相近。而发酵温度按第1～7d,41～43℃;第8～18d,44～46℃;第19～20d,47～48℃模式控制,低盐固态酱油的色率及红色指数指标较好,氨态氮的生成率最高。     

Effects of storage at chilling temperature on ion absorption,salt retention capacity and respiratory pattern in yam tubers

Yams, like most tropical crops, are subject to chilling injury when stored at temperatures below 10°C. Membrane permeability changes are considered to be among the causative factors. Some physiological parameters associated with the cell membranes were therefore examined in yam tuber tissue. It was established that incipient chilling injury could be rapidly detected by changes in ion absorption and salt retention capacities of tuber disks. Chilling effects were also reflected by changes in respiratory rate. It is proposed that these techniques can be used for rapid screening of tubers of a wide range of yam varieties, to establish optimum and minimum safe storage temperatures.     

微波对稻谷储藏过程脂肪酶和脂肪酸的影响

为研究微波对稻谷储藏品质的影响,采用2 450 MHz微波处理稻谷,于不同温度(8、20、30℃)下储藏180天,研究储藏过程稻谷脂肪酶活性、游离脂肪酸含量及其组成。结果表明,经低强度的微波条件处理后,稻谷脂肪酶活力和游离脂肪酸的含量均有提高,不饱和脂肪酸含量降低。稻谷储藏过程中,脂肪酶活力逐渐降低,游离脂肪酸含量增加,脂肪酸组成发生变化,低强度微波处理对稻谷的储藏品质影响不大。     

Combined effects of freezing rate, storage temperature and time on bread dough and baking properties

This study compares the effects of freezing temperature and rate as well as storage temperature and time on the quality of frozen dough. Yeasted bread dough was frozen using four freezing rates (19-69 °C/h), then stored at −10, −20, −30, or −35 °C for up to 180 days. Dough strength diminished with longer storage time and higher storage temperatures. Cryo-SEM showed that dough stored at −30 and −35 °C had the least damaged gluten network. NMR studies showed that more rapidly frozen dough, and that stored at lower temperatures had lower transverse relaxation (T₂) times (9-10 ms). However, dough stored at −20 °C displayed the highest yeast activity among samples. Bread loaf volume decreased with storage time, and bread made from dough stored at −20 °C showed the highest loaf volume. Breads produced from −30 and −35 °C stored dough displayed less change in the texture profile during storage as well as less change in T₂ values. Response surface analysis showed that optimal properties occurred at freezing rates of around 19-41 °C/h and storage temperatures of −15 to −20 °C.     

食用胶复配对微波复热鸡米花品质的影响

针对微波复热鸡米花的加工工艺,在预实验基础上选用黄原胶、卡拉胶以及魔芋胶以不同比例复配,研究其对最终产品品质的影响。微波复热后以鸡米花的脆性作为主要评定指标,同时对制品进行物理性质分析及感官评价,筛选出微波复热后品质最优的胶体复配比例。结果表明,向浸蘸溶液中添加三种食用胶中的任意一种或任意两种食用胶复配添加时,均可以显著改善微波复热后鸡米花的脆性(p<0.05)。而三种食用胶等比例复配对微波复热鸡米花品质则没有明显改善作用。卡拉胶1.00%的添加量会对产品风味产生不良影响。其中0.50%黄原胶和0.50%卡拉胶复配时,微波复热后鸡米花的脆性显著提高,外壳水分和油分含量显著降低(p<0.05),感官质量也较高。这表明向浸蘸溶液中添加0.50%黄原胶和0.50%卡拉胶复配食用胶可以很大程度上改善微波复热鸡米花的食用品质。     

微波处理真空包装对葡萄贮藏品质和生理变化的影响

研究了微波、真空包装以及微波处理真空包装对葡萄贮藏过程中果实的耐压力、可溶性糖、VC、多酚氧化酶(PPO)活性的影响以及感官评定分析。研究结果表明:采用微波真空包装的葡萄果实耐压力、可溶性糖、VC的变化均小于其他处理方式且变化最小,多酚氧化酶(PPO)活性降低最大,感官评定最好。微波处理真空包装可以有效地降低多酚氧化酶(PPO)活性和果实的呼吸强度,提高了抗氧化酶的活性,有利于果实的贮藏保鲜。      

淀粉老化对微波膨化影响的研究

采用Ｘ－ 衍射方法确定了淀粉物料的老化程度,并研究了淀粉的老化对其微波膨化的影响,探讨了淀粉老化对微波膨化影响的机理。     

Influence of the temperature of salt brine on salt uptake by Ragusano cheese

The influence of temperature (12, 15, 18, 21, and 24 degrees C) of saturated brine on salt uptake by 3.8-kg experimental blocks of Ragusano cheese during 24 d of brining was determined. Twenty-six 3.8-kg blocks were made on each of three different days. All blocks were labeled and weighed prior to brining. One block was sampled and analyzed prior to brine salting. Five blocks were placed into each of five different brine tanks at different temperatures. One block was removed from each brine tank after 1, 4, 8, 16, and 24 d of brining, weighed, sampled, and analyzed for salt and moisture content. The weight loss by blocks of cheese after 24 d of brining was higher, with increasing brine temperature, and represented the net effect of moisture loss and salt uptake. The total salt uptake and moisture loss increased with increasing brine temperature. Salt penetrates into cheese through the moisture phase within the pore structure of the cheese. Porosity of the cheese structure and viscosity of the water phase within the pores influenced the rate and extent of salt penetration during 24 d of brining. In a previous study, it was determined that salt uptake at 18 degrees C was faster in 18% brine than in saturated brine due to higher moisture and porosity of the exterior portion of the cheese. In the present study, moisture loss occurred from all cheeses at all temperatures and most of the loss was from the exterior portion of the block during the first 4 d of brining. This loss in moisture would be expected to decrease porosity of the exterior portion and act as a barrier to salt penetration. The moisture loss increased with increasing brine temperature. If this decrease in porosity was the only factor influencing salt uptake, then it would be expected that the cheeses at higher brine temperature would have had lower salt content. However, the opposite was true. Brine temperature must have also impacted the viscosity of the aqueous phase of the cheese. Cheese in lower temperature brine would be expected to have higher viscosity of the aqueous phase and slower salt uptake, even though the cheese at lower brine temperature should have had a more porous structure (favoring faster uptake) than cheese at higher brine temperature. Therefore, changing brine concentration has a greater impact on cheese porosity, while changing brine temperature has a larger impact on viscosity of the aqueous phase of the cheese within the pores in the cheese.     

Impact of storage environment on the efficacy of hermetic storage bags

Small hermetic bags (50 and 100 kg capacities) used by smallholder farmers in several African countries have proven to be a low-cost solution for preventing storage losses due to insects. The complexity of postharvest practices and the need for ideal drying conditions, especially in the Sub-Sahara, has led to questions about the efficacy of the hermetic bags for controlling spoilage by fungi and the potential for mycotoxin accumulation. This study compared the effects of environmental temperature and relative humidity at two locations (Indiana and Arkansas) on dry maize (14% moisture content) in woven polypropylene bags and Purdue Improved Crop Storage (PICS) hermetic bags. Temperature and relative humidity data loggers placed in the middle of each bag provided profiles of environmental influences on stored grain at the two locations. The results indicated that the PICS bags prevented moisture penetration over the three-month storage period. In contrast, maize in the woven bags increased in moisture content. For both bag types, no evidence was obtained indicating the spread of Aspergillus flavus from colonized maize to adjacent non-colonized maize. However, other storage fungi did increase during storage. The number of infected kernels did not increase in the PICS bags, but the numbers in the woven bags increased significantly. The warmer environment in Arkansas resulted in significantly higher insect populations in the woven bags than in Indiana. Insects in the PICS bags remained low at both locations. This study demonstrates that the PICS hermetic bags are effective at blocking the effects of external humidity fluctuations as well as the spread of fungi to non-infected kernels.     

Effect of fish,starch and salt contents on the microstructure and expansion of fish crackers (‘keropok’)

Light microscopy studies on the fish cracker gel and expanded product (‘keropok’) emphasised the role of fish proteins in the starch expansion process. The addition of salt (20 g kg⁻¹) in the ‘keropok’ helped to distribute evenly the starch in the fish protein. Formation of thin fish muscle bundles assisted the expansion of ‘keropok’. At 700–900 g kg⁻¹ fish content, the fish muscle bundles formed a continuous network that caused a drop in the ‘keropok’ expansion. From the scanning electron microscopy study, ridges were found in samples (containing 600–900 g kg⁻¹ fish content) with 20 g kg⁻¹ salt at high magnification. © 1999 Society of Chemical Industry     

Interaction of brine concentration, brine temperature, and presalting on salt penetration in Ragusano cheese

Thirty-one 3.6-kg blocks of Ragusano cheese were made on each of 6 different days (in different weeks) starting with a different batch of milk on each day. On d 1, 3, and 5, the cheeses were not presalted and on d 2, 4, and 6, all cheeses were presalted (PS). One of the 31 blocks of cheese was selected at random for analysis before brine salting (i.e., on d 0). The remaining 30 blocks were randomly divided into 2 groups of 15 blocks each; one group was placed in 18% brine (18%B) and the other group was placed in saturated brine (SB). For the 15 blocks within each of the 2 brine concentrations (BC), 5 blocks were placed in a brine tank at 12° C, 5 at 15° C, and 5 at 18° C, and submerged for 24 d. The research objective was to determine the combined impacts (i.e., interactions) of PS the curd before stretching, BC (SB vs. 18%B), and brine temperature (BT; 12, 15, and 18° C) on salt uptake, moisture content, and yield of Ragusano cheese. Although BC, BT, and PS each had their own separate impacts on salt uptake, there was little interaction of these effects on salt uptake when they were used in combination. The PS most quickly delivered salt to the interior of the cheese and was the most effective approach to salting for controlling early gas formation. There were strong separate impacts of BC, BT, and PS on cheese moisture content, moisture loss, and net weight loss, with BC having the largest separate impact on these parameters. Reducing BT reduced salt content and increased moisture, but the effects were small. The more important effect of reduced BT was to reduce growth of gas forming bacteria. The 18%B produced higher moisture, and less moisture and weight loss than SB. The effect of interactions of BC, BT, and PS on moisture loss and net weight loss were small. To achieve the maximum benefit from the various approaches to salting for controlling early gas formation in Ragusano cheese, PS combined with slightly lower BT (i.e., 15° C instead of 18° C) should be used. Although using 18%B instead of SB did increase salt uptake, the point at which improved salt uptake occurred due to use of 18%B did not provide benefit in prevention of early gas formation, as reported separately. However, use of 18%B instead of SB provided a 9.98% increase in cheese yield due to reduced moisture loss during brining; this would be very attractive to cheese makers. The increase in yield needs to be balanced against the risk of growth of undesirable bacteria in the 18%B and the creation of another cheese quality defect.     

微波脱脂过程中木材温变特性研究

以马尾松木材为研究对象,较系统地研究了微波脱脂处理过程中,微波辐射时间、辐射强度和木材初含水率三因素对木材温度变化特性的影响规律.结果表明:在微波脱脂处理过程中,木材的温度变化分为快速升温和恒温脱脂两个阶段;随微波辐射强度的增大和木材初含水率的减小,升温段的温升速率、温度峰值和平均终了温度都增大;辐射时间对升温段的温升速率、温度峰值和平均终了温度都无显著影响.     

微波对马铃薯淀粉特性影响的研究

采用DM2500P偏光显微镜、NDJ-5S黏度仪、RVA研究微波处理对马铃薯淀粉的特性的影响。结果表明:原淀粉颗粒呈椭圆形,而微波作用后的淀粉的颗粒结构被破坏,外形为不规则颗粒、纤维状;马铃薯原淀粉糊和微波淀粉的表观黏度随剪切速率的增大而降低,呈剪切稀化现象;微波淀粉的剪切应力和剪切速率的变化呈正相关;马铃薯原淀粉的糊化温度为64.5℃,峰值黏度是11491cp,保持黏度为3105cp,最终黏度是3653cp;微波马铃薯淀粉的RVA糊化黏度曲线中未出现明显的峰值黏度,微波淀粉保持黏度为232.00cp,最终黏度是578.00cp。     

复合有机盐溶液对猪肉保鲜效果的研究

将几种有机盐复合后处理猪肉,通过L9(34)正交试验,在22℃下对保鲜效果进行检测分析.结果表明,各水平组合均有一定保鲜作用,以0.5%柠檬酸钠、8%醋酸钠、8%山梨酸钾组合效果最佳,能有效控制TVBN增加,延缓pH上升,对肉样感官指标无较大影响,保鲜期达15d.     

Effect of moisture content and water mobility on microwave expansion of imitation cheese

The effects of moisture content (60–45%), and refrigerated storage (1–9 days) on the functional properties, water mobility and microwave expansion of imitation cheese are investigated. Cheese hardness, elastic (G′) and viscous moduli (G″) increased with decreasing moisture content and decreased during storage. Flowability, loss tangent (tan δ) and water mobility decreased with decreasing moisture content and increased during storage. Microwave expansion of imitation cheese decreased with decreasing moisture content and increased with prolonging storage time prior to microwaving. The changes in texture, rheology and flowability of cheese with decreasing moisture content, changes in water mobility and storage time reflected the level of cheese plasticisation by water and had strong linear correlations with microwave expansion. This work provides evidence that moisture content influences microwave expansion of imitation cheese by providing the driving force for expansion and plasticising the cheese matrix.     

贮存温度和贮存时间对复原乳稳定性的影响

研究了贮存温度和贮存时间对复原乳的pH值、流变特性、粒径、乳析率和离心沉淀率的影响,在此基础上分析了贮存过程中乳浊液粒径与乳析率、离心沉淀率之间的相关性。结果表明:随着贮存温度的升高,复原乳的pH值与表观黏度逐渐降低,而随着贮存时间的延长,二者均先升高后降低,其中25℃和37℃下贮存在第15天时达到最大值,而55℃下贮存在第7天时达最大值;贮存过程中乳浊液顶部粒径d4,3与乳析率有较好的相关性(P<0.05),二者均随着贮存温度的升高和贮存时间的延长而增大;贮存过程中乳浊液底部粒径d4,3与离心沉淀率有很好的相关性(P<0.05),二者随着贮存温度的升高先增大后减小,在37℃时达最大值,随着贮存时间的延长均有所增大。