挤压蒸煮在乳制品中的应用

介绍了挤压蒸煮在乳制品中的应用；论述了挤压蒸煮的优越性及其在干酪，酪蛋白酸盐，脂肪类似物的制备等方面的广阔应用前景及其重要意义。     

挤压蒸煮技术在变性淀粉生产中的应用

主要阐述了挤压加工原理,以及用挤压机作反应器生产氧化、酯化、交联和醚化等多种类型的变性淀粉,并对其相关性质进行了简要分析。认为挤压蒸煮技术是快速、连续生产多种变性淀粉的一种经济可行的方法。     

基于挤压蒸煮的荞麦粉加工品质改良及其机制研究

文章分析了挤压蒸煮对荞麦粉室温黏度和凝胶特性的影响,并利用体积排阻色谱测定了淀粉的分子量分布,探讨预糊化处理改善荞麦粉凝胶特性的机制;基于面带质地评价方法,优化预糊化荞麦粉在50%荞麦挂面中的添加比例。结果表明:荞麦粉经挤压蒸煮后,常温水中可形成凝胶;室温黏度显著增加;在主区温度200℃,水分含量18%,螺杆转速220r/min的条件下,所得预糊化荞麦粉中聚合度(DP)为6～50的支链淀粉分子最多,且此时凝胶强度最大。当预糊化荞麦粉添加量为10%时,面带抗拉能力最佳,黏附能力适中。由此可见,预糊化荞麦粉中特定链长的支链淀粉分子(DP 6～50)与凝胶品质呈正相关;50%荞麦挂面中添加适量预糊化粉可显著改善挂面的加工性能。     

Continuous emulsification and gelation of dairy ingredients by HTST extrusion cooking: production of processed cheeses

Processed cheese was prepared batchwise and by extrusion cooking. The cheddar-based cheese mix contained varying amounts of polyphosphate ions, rework, lipids, water and/or non cheese proteins. The extrusion conditions (barrel temperatures, screw speed and screw profile) were also varied. The texture, structure and colour characteristics of batch and extrusion-processed cheeses were evaluated using penetrometry, scanning electron microscopy and reflectance measurements. The degree of fat emulsification was assessed and the proportion of casein nitrogen sedimentable by ultracentrifugation was determined, as a means of following micellar disruption plus casein restructuring due to extrusion and to the additional creaming step. Results indicate that extrusion cooking can be used to continuously mix, melt, emulsify and gel the cheese mix constituents, and that processed cheeses or cheese analogues of varying texture (spreadable to sliceable) can be obtained, with a mean residence time in the extruder of about 100 seconds.     

改良挤压技术制备低蛋白质构米的研究

以粳米淀粉为原料,使用改良挤压技术制备低蛋白质构米,利用响应面分析法考察加工参数如物料含水率、螺杆转速和机筒温度的变化对低蛋白米质构特性的影响,并且以粳米的质构指标为参考指标,优化低蛋白质构米的制备工艺。结果表明,最优工艺参数为物料含水率35%,螺杆转速30r/min,机筒温度(糊化区温度)120℃,该工艺条件下,低蛋白质构米的硬度为(9 122±244)g,黏性为(-983±49)g.s,弹性为0.67±0.05,接近粳米的质构特性(硬度为(8 996±196)g,黏性为(-627±41)g.s,弹性为0.62±0.03)。同时,与粳米相比,其蛋白质含量非常低,为0.43%±0.01%,而且外观和色泽接近市售粳米,米粒完整,颜色均一,圆润光滑,轮廓分明,米质结构紧密。     

热塑挤压蒸煮处理技术对大豆蛋白基本特性的影响

利用双轴挤压蒸煮处理技术对大豆蛋白进行处理,从质构特性、功能特性及营养特性等三方面对挤出物的组织化效果进行研究。以三个挤压操作参数供水率、螺杆转速和腔体温度为输入参数,挤出物的最大剪切力、复水率、持水率和蛋白质体外消化率为响应参数,探索挤压蒸煮系统操作参数对大豆蛋白质基本特性的影响规律,统计分析表明,三个挤压操作参数与响应参数之间存在显著的相关关系,所得拟合回归模型具有较高的可信度。挤压蒸煮处理操作参数对大豆蛋白的组织化效果有明显影响。     

Thiamine destruction during extrusion cooking as an indicator of the intensity of thermal processing

Assessment of the intensity of high temperature-short time (HTST) extrusion cooking was studied by measuring the extent X_A of thiamine destruction. Small quantities of thiamine hydrochloride (0.1–0.7 g per 100 g) were mixed with wheat flour (containing ∼ 14% water) prior to extrusion experiments. Results indicate that thiamine destruction follows an apparent first-order reaction and that the rate constant K of destruction, calculated from near isothermal extrusion experiments at 133, 142 or 152°C (product temperature), follows an Arrhenius relationship with an activation energy of 49.9 kJ/mol.
K values were calculated from experimental determination of X_A and of the residence time distribution (RTD) in the effective heating zone of the extruder.
The influence of product temperature (just before the die), water content during extrusion and speed of screw rotation on the overall K (for non-isothermal extrusion experiments) was determined and analysed by multiple regression. Results show that thiamine destruction X_A can be predicted by means of a linear mathematical model.
Each experimental X_A value can be used, in combination with Arrhenius equation constants and RTD, to express a given extrusion process in terms of equivalent isothermal temperature and equivalent plug flow residence time.     

西农黑大穗小麦挤压膨化加工研究

以普冰9946小麦为对照,研究西农黑大穗挤压膨化过程中加工温度、物料含水量、喂料速度变化对挤压膨化的扭矩、4区压力、5区压力、单位机械能耗、产品比容、径向膨化率、脆度、硬度的影响。结果表明,在试验范围内,温度为T1时,西农黑大穗产品比容、径向膨化率高,单位机械能耗高;温度为T3时,产品脆度高、硬度低,膨化率低。含水量为20%时,产品物理特性相对较好;含水量为22.5%时,单位机械能耗较低。喂料速度为20 g/min时,产品物理特性较好,单位机械能耗较高。加工过程中,西农黑大穗的扭矩、压力均高于对照,单位机械能耗和产品物理特性与对照差异极显著(P0.01)。     

Effect of grain hardness on bioavailability of iron in wheat as determined using the coupled invitro digestion/Caco-2 model

The impact of grain hardness on iron bioavailability from a set of wheat genotypes with varying hardness indices was determined. This may help us to consider grain hardness as an important parameter along with other established parameters for selecting food crops for future biofortification programs to combat iron deficiency linked to global health problem. The bioavailability and dialysability of iron were determined using the coupled in vitro digestion/Caco-2 model. The grain hardness and its molecular basis along with grain iron, phytate and inorganic phosphorous (Pi) contents were also evaluated. The data indicated that iron concentration in the genotypes ranged from 21 to 50 μg/g of dry matter. The hardness indices varied from as low as 28 for the derivative BTC17 to as high as 92 for the landrace IITR 26, almost similar to that of WL711, a wild type cultivar considered as control in this study. Low variability was however observed for the phytate and Pi contents. A significant negative correlation was observed between grain hardness vs. dialysability (r = −0.73) and bioavailability (r = −0.75) of iron. The results suggest that the hardness index which profoundly affects milling process, particle size of flour, milling yield and end-use also influences dialysability and bioavailability of iron from wheat.     

挤压蒸煮改性黄精粉的制备及品质评价

目的:提高黄精食用及功能品质。方法:以冻干鲜黄精粉为原料对照品,九蒸九晒黄精粉为工艺对照品,分析比较挤压蒸煮黄精粉的人体感官、电子感官、色度、流动性、冲调性、浸出物、总多糖和总皂苷含量等质量特性。结果:挤压蒸煮可有效消除鲜黄精的不良口感,改善黄精粉的色泽和流动性。与九蒸九晒黄精粉相比,挤压蒸煮黄精粉的总多糖和总皂苷含量显著增加,增幅分别为49.27%,69.10%。结论:挤压蒸煮能有效改善黄精的食用品质和功能特性,提高工艺的可控性和稳定性。     

Physical and technofunctional properties of yellow pea flour and bread crumb mixtures processed with low moisture extrusion cooking

The potential utilization of yellow pea flour and bread crumb blends was investigated to generate nutritionally-dense extruded products with superior physical and/or technofunctional properties. Yellow pea flour mixed with bread crumb at different ratios were processed using low-moisture twin-screw extrusion cooking conditions to examine the effect of blending ratios and feed moisture contents on physical (that is, radial expansion index, extrudate density, microstructure, texture, and color) and technofunctional (that is, emulsifying capacity, emulsifying stability, water solubility [WS], water binding capacity [WBC], oil binding capacity [OBC], and pasting) properties of the final products. Compared to the two feed materials alone, samples produced with yellow pea flour and bread crumb blends showed lower hardness and higher crispiness. Moisture content (12% to 18%) was found to significantly affect physical and technofunctional properties. With an increase in feed moisture content from 12% to 18%, the WBC of the extrudates increased while the WS decreased. Extrudates produced with higher feed moisture content, and higher yellow pea flour content had higher setback viscosity. Among all formulas and feed moisture contents studied, extrudates produced with 50% yellow pea flour and 50% bread crumb at 12% feed moisture content had the highest radial expansion and bigger cells with thinner cell walls. This study has shown that incorporation of yellow pea flour and bread crumb in extrusion cooking process could be used to develop nutritionally-dense foods with improved physical and technofunctional properties.     

Influence of food processing on iron availability in vitro from extruded maize-based snack foods

Samples of an extruded maize-based snack food taken at various points during manufacture were digested in vitro under simulated physiological conditions. The proportion of iron diffusing across a semi-permeable membrane was used as an index of bioavailability. Iron diffusibility increased from less than 3 % in raw whole maize to over 20 % in the finished product. Four processing stages were found to be responsible for this enhancement: (I) refining of raw maize, (2) product formulation, (3) extrusion cooking, (4) addition of flavourings. The extrusion cooking process itself was responsible for only a small part of the increase in iron diffusibility. There was a reduction in iron content due to refining, but a small increase in iron content due to product formulation and extrusion cooking. The various factors associated with each stage of snack food manufacture are discussed in relation to their potential influence on iron availability.     

干燥温度对改良挤压法制备的全谷物质构米品质的影响

研究干燥温度(40～80℃)对改良挤压法制备的全谷物质构米的营养特性、食用品质和热力学特性的影响。结果表明:干燥温度在40～80℃,全谷物质构米的粗脂肪和脂肪酸含量随温度升高而降低,对其他营养素无明显影响;当干燥温度低于50℃时,全谷物质构大米样品具有易消解、米饭较软、黏弹性大、口感较好的食味品质;同时,DSC的试验数据表明干燥温度低于50℃时,全谷物质构米具有起始糊化温度略低,糊化时间更短,糊化焓更小的热力学特性。     

Effect of dietary mineral phosphorus and phytate on in situ ruminal phytate disappearance from different concentrates in dairy cows

The first objective of this study was to determine the influence of dietary composition on the in situ disappearance of phytate (InsP₆) from wheat, corn, soybean meal, and rapeseed meal [solvent-extracted, without (RSM) or with (hRSM) heat treatment] in the rumen of dairy cows. The second objective was to assess the primary degradation products of InsP₆ in the rumen. Three diets differing in phosphorus and InsP₆ concentration (basal diet = 0.38% P in dry matter; high-P diet = 0.56% P; high-InsP₆ diet = 0.39% P) were fed to 3 ruminally fistulated lactating Jersey cows in a 3 × 3 Latin square. Ground concentrates (sieve size = 2 mm) were incubated in polyester bags in the rumen for 2, 4, 8, 16, and 24 h. The bag residues were analyzed for P, InsP₆, isomers of lower inositol phosphates (InsP₅, InsP₄, InsP₃), and crude protein. The InsP₆ disappeared more rapidly from cereal grains than from oilseed meals; however, after 24 h of incubation ≥95% InsP₆ had disappeared from all concentrates except hRSM (57%; diet average). Feeding the high-InsP₆ diet increased InsP₆ disappearance for oilseed meals, but not for corn and wheat. The predominant InsP₅ isomer in all bag residues was Ins(1,2,4,5,6)P₅ followed by Ins(1,2,3,4,5)P₅ and Ins(1,2,3,4,6)P₅. A further InsP₅ isomer [Ins(1,3,4,5,6)P₅] was detected in both rapeseed meal bag residues. Feeding the high-InsP₆ diet led to lower concentrations of Ins(1,2,4,5,6)P₅ and Ins(1,2,3,4,5)P₅, whereas an interaction between diet, concentrate, and time occurred for Ins(1,2,3,4,6)P₅ and Ins(1,3,4,5,6)P₅. The results confirm the high potential of rumen microorganisms to hydrolyze InsP₆; however, increasing the amount of InsP₆ in the diet can further enhance InsP₆ hydrolysis, which may be relevant when concentrates with slowly degradable InsP_6, such as RSM or heat-treated concentrates, are fed to dairy cows. Based on the concentrations of InsP₅ isomers, 3 and 6 phytases appear to play a major role in the rumen. Conversely, intrinsic plant phytase activity appears to be less relevant as the percentage of its primary hydrolysis product, Ins(1,2,3,4,5)P₅, changed only slightly upon using wheat known for high intrinsic phytase activity instead of the other concentrates. Additional information regarding the factors influencing the extent of ruminal InsP₆ disappearance will require further studies to determine the phytase activity of rumen microorganisms and the characteristics of their respective phytases.     

全谷物重组速煮糙米的理化性质和蒸煮品质研究

本研究以低值早籼稻糙米为原料,采用挤压质构重组技术,研究开发速煮糙米产品,攻克了糙米难以煮制、口感粗糙及食用不方便等难题,并对产品的理化性质和蒸煮、食用品质进行了分析研究。结果显示:重组糙米的B族维生素等各项营养指标与天然糙米接近。在30、40℃下重组糙米的吸水率高于原料糙米和精白米,50℃时吸水率介于原糙米和精白米之间;重组糙米糊化温度低于原糙米和精白米,糊化时间减少。衰减值降低,表明糙米重组后不易发生回生。质构和感官测试表明重组糙米色泽淡黄,外观光滑,透明度高,蒸煮8min即达到完全熟化,其硬度低于精白米和原糙米。产品货架期超过6个月。      

The effect of germination on the phytase activity,phytate and total phosphorus contents of some Nigerian‐grown grain legumes

BACKGROUND: Grain legumes are under‐exploited as possible sources of phytase for the poultry industry. The current study was conducted to assess the effect of germination on phytase activities, phytate and total phosphorus content in samples of Nigerian‐grown grain legumes. The legumes screened were African yambean (AYB, Sphenostylis stenocarpa), lima bean (Phaseolus lunatus), pigeon pea (Cajanus cajan), cowpea (Vigna unguiculata) and groundnut (Arachis hypogea). RESULTS: Phytase activity was low in AYB, lima bean and pigeon pea but high in cowpea and groundnut. Phytate content ranged between 3.01 g kg^?1 and 8.95 g kg^?1 while total phosphorus content ranged between 2.63 g kg^?1 and 5.93 g kg^?1. The grain legumes with higher phytase activity recorded the lowest phytate and phosphorus content. During germination there was an initial 4‐fold to 35‐fold increase in phytase activity after 6–7 days of germination followed by a decrease until 10 days (P < 0.05). The increase in phytase activity during germination was accompanied by a significant reduction in phytate (P < 0.05) and a small but significant increase in total phosphorus. CONCLUSION: The increase in phytase activity and the accompanying decrease in phytate content could have a positive implication for the nutrition of poultry and ruminants and for the environment. Copyright © 2010 Society of Chemical Industry