冷冻对不同部位草鱼肉鲜度和滋味的影响

以不同部位草鱼肉(背肉、腹肉、红肉)为对象,采用高效液相色谱法(HPLC)、氨基酸自动分析法测定了冷冻前后草鱼肉水溶性成分的变化。结果表明:不同部位的鱼肉以及冷冻前后其ATP关联物、鲜度和游离氨基酸含量各不相同。新鲜草鱼背肉、腹肉、红肉的K值分别为1.82%、2.71%、7.38%,在-18℃下冷冻48h之后,背肉、腹肉的K值没有明显的变化,红肉K值有增加;游离氨基酸对滋味贡献较大,新鲜草鱼背肉和腹肉中游离氨基酸含量高于红肉,但背肉和腹肉中天冬氨酸和谷氨酸含量显著低于红肉,组氨酸含量显著高于红肉;冷冻后,背肉和腹肉中游离氨基酸含量有所增加,但红肉中游离氨基酸含量降低;冷冻对草鱼红肉部分鲜度和滋味的影响要大于对背肉和腹肉的影响,因此在草鱼冷冻和加工中要对红肉部分特别注意。     

冷冻食品的保存与调理

冷冻食品从制造、仓储、运送到消费者购买、存放，这一连串的步骤都要在-18℃以下进行。象这样各阶段链串式的低温保存，我们称之为冷冻链，为何要有冷冻链的存在呢？要解释这点，我们必须先了解温度变化对冷冻食品质量产生的影响。     

不同冷冻工艺对龙头鱼品质的影响

以液氮冷冻、-80℃超低温冷冻与普通冰箱冷冻三种方式对龙头鱼进行冷冻处理,研究不同冷冻方式对龙头鱼p H、TVB-N、保水性等指标的影响,为龙头鱼的加工利用提供理论依据和技术指导。结果表明:经不同冷冻方式冷冻的龙头鱼p H、TVB-N、甲醛含量相差不大;样品的保水性能由高至低依次为-18℃组-80℃组液氮组;质构方面,龙头鱼在冷冻过程中其硬度、弹性和咀嚼性均有一定程度的下降,但液氮组下降的幅度最小;由感官评价可知,不同冷冻方式处理的天妇罗龙头鱼质地、可接受性等方面均有不同程度的下降,三种冷冻方式中液氮组天妇罗龙头鱼的感官综合评分比其他两组高。从冷冻品质综合考虑,选择液氮冷冻处理更有利于龙头鱼的品质。     

影响茶油冷冻效果的因素分析

对3种不同工艺茶油(鲜榨茶油、原香茶油、精炼茶油)进行冷冻试验研究。研究温度、水分含量、含杂量、主要脂肪酸组成、反式脂肪酸含量、活性营养成分等多个因素对茶油冷冻效果的影响。结果表明:造成不同工艺茶油冷冻效果不同的主要因素可能为加工过程中产生的反式脂肪酸和保留的活性营养成分的含量不同引起的,反式脂肪酸含量较高的精炼茶油,更易产生絮状析出物和冻结状态,含活性营养成分较多的鲜榨茶油和原香茶油在-4℃下会产生结晶颗粒析出物;冷冻温度、油脂中的水分含量、含杂量对所有工艺生产的茶油的冷冻效果均有影响,温度越低,冷冻速度越快,在-4℃下不同工艺茶油会产生不一样状态的冷冻析出物,而水分含量和含杂量越高,冷冻速度越快。     

金属离子对冷冻法生产大豆蛋白的影响

研究了在大豆蛋白溶液中加入不同的金属离子,随后采用冷冻法处理生产大豆蛋白并确定了金属离子对冷冻法生产大豆蛋白的影响.结果表明,在固液比1∶20、加热温度50℃、pH5时,加入金属离子后-18℃条件下冷冻24h,其蛋白质含量有显著增加,且相同条件下在大豆蛋白溶液中加入氯化钙和氯化镁离子比加入氯化钠离子处理后的蛋白质含量要高,符合霍夫曼斯特离子序.其生产的蛋白质的溶解度随着金属化合物溶液浓度增大而增加,持水性则呈现出不同的趋势 可见,钙离子及镁离子对冷冻法生产大豆蛋白具有一定促进作用,而钠离子作用较弱.     

当今速冻设备的发展

<正> 若将冷冻食品与“新鲜”食品相对而论,是会引起严重的误导。举个例说,从海中打捞上来几分钟内进行迅速冻结的鱼,要比打捞后几小时,甚或几天后才出售的“新鲜”鱼,在味道、口感、外观及营养各方面都较佳。目前,市场上对在不同季节和不同地域所生产的食品有着大量的需求,从而加快了冷冻新鲜食品市场的发展,使现代冷冻工业应运而生,先进的冷冻技术也不断得到研究与开发。     

乳品厂鲜奶急冷冷藏设备

简述几种传统的快速冷却设备和氨冷冻站的缺点,介绍了冻缸冷排、底冷式奶仓、调温型蓄冷奶仓和冰冷奶仓这四种急冷和冷藏相结合的适合乳吕厂推广采用的新型鲜奶急冷冷藏设备。     

冷冻剑结构对块冰机制冰性能影响的数值模拟

目的：在直冷式块冰机冰模蒸发器内部增设冷冻剑以实现快速制冰。方法：使用COMSOL模拟冷冻剑截面形状及冷冻剑倾角对制冰过程的影响。结果：随着制冰过程的持续进行,增设不同截面形状冷冻剑的冰模内部平均温度不断降低,冰模内固相体积分数也随时间而增加,但在相同时间内增设圆形截面冷冻剑的冰模内部平均温度要比三角形、矩形和菱形低0.1～0.2 ℃。此外,冷冻剑倾角越小制冰速率越快。结论：冷冻剑截面形状为圆形或近圆形时,制冰速率较快;且在保证便于脱冰的前提下,应尽可能减小冷冻剑倾角。     

文献导读

<正>冷冻条件和解冻方式对酵子冷冻面团馒头品质的影响研究酵子冷冻面团生产过程中冷冻条件和解冻方式对冷冻面团和成品馒头品质的影响。通过测定冷冻面团不同冷冻条件下的发酵力和成品馒头的品质变化,找出制作酵子冷冻面团馒头适合的冷冻条件;同时测定不同解冻方式对冷冻面团和成品馒头品质的变化,找出适合酵子冷冻面团生产的解冻方     

酵子与酵母混合对冷冻面团馒头品质的影响研究

研究了酵母与酵子不同混合比例对冷冻面团馒头品质的影响。通过测定不同发酵时间下馒头的基本指标、质构和感官总分,找出制作冷冻面团馒头最适的混合比例和解冻后的发酵时间。研究表明:酵母与酵子混合比例为4∶1,解冻后的发酵时间为45 min时,做出的冷冻面团外观较好,成品馒头的感官总分较高。单纯用酵母做出的冷冻面团表皮容易开裂和坍塌,但是酵子添加比例较大时,发酵剂的发酵活力降低,解冻后需要将长的发酵时间。添加适量的酵子制作出来的冷冻面团表皮较光滑,不易开裂和塌陷,制作馒头的口感和风味要比单纯使用酵母制作的馒头要好很多,同时大大的缩短了解冻后的发酵时间。     

Effect of low‐trans margarine on physicochemical and sensory properties of puff pastry1

The influence of the low‐trans (<1% of total fatty acids) puff pastry margarine and the rest period between laminating on dough physical characteristics and puff pastry quality was investigated. Experiment was planed according to factorial plan 3² with independent variables: quantity of puff pastry margarine (35–55% based on flour, variation interval 10) and rest period (15–45 min, variation interval 15). The experiment involved two margarine samples (MLT1 and MLT2) of similar fat phase composition, but whose physical properties were, statistically speaking, significantly different. The results show that the pastry containing 35% of margarine MLT1 and allowing the rest period of 30 and 45 min has a lift of above 4.0, it is of minimal firmness and has a high specific volume (3.5 cm³ g^?1). Having used puff pastry margarine MLT2, the highest quality of dough and pastry was achieved in the sample containing 55% of margarine and with the maximum rest period of 45 min. The sample mentioned showed an excellent lift of 5.3 and had a specific volume of 4.0 cm³ g^?1, but it as well exhibited the maximal firmness of pastry. The application of puff pastry margarine MLT1 can result in a satisfactory quality of pastry, but it can also cause a reduction in the fat content by 7.5% and in the content of trans fatty acids by two times, while the energy value is reduced by 12% when compared with the pastry containing puff pastry margarine MLT2.     

MEASUREMENTS ON PASTRY MARGARINES USING A SLIDING PIN CONSISTOMETER

A sliding pin consistometer (SPC) has been shown to be suitable for differentiating significantly (P< 0.01) between three commercial pastry margarine products described as Hard, Medium and Soft at sample temperatures of 20 and 10°C. SPC average force values were related linearly (r = 0.98) to sample temperature over the range of 0.6 to 37°C. The SPC gives objective information which should be useful to manufacturers of pastry margarines as a simple quality test. It appears to have an advantage over more widely used extruders or penetrometers in that it is portable and easy to use.     

冰淇淋生产中的油脂

综述了油脂在冰淇淋中的作用和冰淇淋生产中常用的油脂及其代用品。详细论述了稀奶油及奶油的组成成分、规格与理化性质；扼要介绍了食用硬化油、人造奶油、起酥油、椰子油、棕榈仁油及棕榈油．以及碳水化合物类脂肪代用品和脂肪酸酯代脂品。     

起酥油及乳化剂让冷饮更"良"

<正>在冷饮行业日新月异的今天,中国的冷饮产品无论从品质、生产工艺、到种类都已今非昔比。其中配料的不断更新发展功不可没。本文介绍了起酥油和乳化剂的应用问题。 一.起酥油在冷饮中的应用 油脂作为冷饮产品的最主要的原料     

FAT CRYSTALS AND THE FLOW RHEOLOGY OF BUTTER AND MARGARINE

Abstract The viscosities of fat crystals extracted by 1 % Aerosol O.T. from butter and margarine have been studied using a Weissenberg Rheogoniometer. By applying the Brodnyan (1959) equation for non-spherical particles to the viscosity data at high rates of shear, after correcting for secondary flow phenomena, it was deduced that the axial ratios of the margarine fat crystals were between 3.05 and 3.94, with the fat crystals from butter lying midway between the two extremes. By applying viscosity equations of the exponential type to such data, it should be possible to calculate the viscosity of butter and margarine at very high rates of shear when the viscosity of the liquid oil in the fat phase and the volume concentration of water drops are known. This information could be useful for predicting the spreadability characteristics of butter and margarine.     

Puff pastry and trends in fat reduction: an update

Puff pastry is a popular nonleavened pastry product with unique textural properties. Puff pastry is processed from laminated dough, comprising alternating and discrete layers of dough and fat. Puff pastry quality can vary substantially depending on the raw material quality and production processes. The high fat content of commercial puff pastry usually containing significant amounts of saturated and trans fats, which are known to be associated with potential health risks, has led to increased demand for lower fat baked products. This review discusses the puff pastry production process and factors affecting puff pastry quality together with strategies to reduce total fat content and improving the fat composition in puff pastries.     

Flow properties of table margarine prepared from lipase-catalysed transesterified palm stearin:palm kernel olein feedstock

The flow properties of an experimental table margarine prepared from Rhizomucor miehei lipase-catalysed transesterified palm stearin:palm kernel olein (PS:PKO) blend at 40:60 was stored for 3 months at test temperatures of 20 and 30°C and determined using a controlled-rate rheometer. A commercial table margarine was used as a comparison. The shear stress-shear rate data was represented well by the Herschel–Bulkley model (r > 0.99). The mean yield stress values during storage were the highest for the experimental table margarine. However, the effect of storage on the mean yield stress was insignificant (p > 0.001). The Power Law model with a yield stress also represented the margarine flow well (r > 0.99) and the Power Law intercepts and slopes were also the highest for the experimental margarines, indicating a higher degree of firmness in the experimental samples. Storage effect was also insignificant (p > 0.05).     

Storage Stability of a Puff Pastry Dough with Reduced Water Activity

A puff pastry dough that remained stable at refrigerated temperatures was developed. Dry heat treatment was used to partially destroy amylase and lipoxygenase in wheat flour. Water activity of puff pastry dough was reduced from 0.98–0.90 by addition of 12g sorbitol/100g flour. The adverse effects of sorbitol on baking properties of puff pastry were alleviated by addition of sodium stearoyl lactylate and gum arabic. The puff pastry dough stored at 5°C in air or nitrogen was stable for 75 days without any significant loss in specific volume or pastry height in comparison with the frozen control.     

人造奶油研究现状及其制备技术

人造奶油具有天然奶油的风味、色泽和可塑性,在食品工业中可用于糕点、饼干等的制作,也可以供家庭中直接食用。通过对人造奶油研究现状及制备技术的研究,提出了人造奶油的发展趋势。     

Ingredient Functionality in Multilayered Dough-margarine Systems and the Resultant Pastry Products: A Review

Pastry products are produced from heterogeneous multilayered dough systems. The main ingredients are flour, water, fat and sugar for puff pastry, and the same plus yeast for fermented pastry. Key aspects in pastry production are (i) building laminated dough containing alternating layers of dough and bakery fat and (ii) maintaining this multilayered structure during processing to allow for steam entrapment for proper dough lift during baking. Although most authors agree on the importance of gluten and fat for maintaining the integrity of the different layers, detailed studies on their specific function are lacking. The exact mechanism of steam entrapment during dough lift and the relative contribution of water set free from the fat phase during baking also remain unclear. This review brings together current knowledge on pastry products and the factors determining (intermediate) product quality. Its focus is on flour constituents, fat, water, and (where applicable) yeast during the different production stages of pastry products. Future research needs are addressed as the knowledge on biochemical and physical changes occurring in flour constituents and other ingredients during pastry production and their effect on product quality is currently inadequate.