猪五花肉红烧过程中脂肪和脂肪酸的变化规律

目的：探讨以猪五花肉为原料的红烧肉加工过程中脂肪和脂肪酸的变化,以期对红烧肉的风味、营养、质地等研究提供参考。方法：对红烧肉加工过程中原料、油炸、炖煮过程样品（0～2 h,每30 min取样）以及成品的粗脂肪含量、过氧化值（peroxide value,POV）、硫代巴比妥酸（thiobarbituric acid reactive substances,TBARS）值以及脂肪酸含量进行测定。结果：五花肉红烧过程中脂肪含量显著下降（P＜0.05）,成品红烧肉脂肪含量比原料肉下降12.14%;POV先增大后减小,在炖煮30 min达到最大值;TBARS值逐渐增大,在炖煮过程中变化显著（P＜0.05）;油酸、棕榈酸、亚油酸和硬脂酸是五花肉脂肪中的主要脂肪酸,在红烧过程中饱和脂肪酸（saturatedfatty acid,SFA）含量变化不大（P＞0.05）,单不饱和脂肪酸（monounsaturated fatty acid,MUFA）含量显著上升（P＜0.05）,多不饱和脂肪酸（polyunsaturated fatty acid,PUFA）含量显著下降。结论：五花肉红烧过程中脂肪含量下降、脂肪发生适度氧化、脂肪酸组分构成发生了改变。     

猪五花肉在三种红烧工艺加工过程中的脂肪氧化规律

目的:研究红烧肉在制作过程中工艺对脂肪氧化和脂肪酸含量变化的影响。方法:以上海本帮、湖南毛氏、东北传统三种工艺红烧肉为研究对象,以其烹制过程中的不同时间(原料肉、炖煮0、30、60、90 min)为取样点,分析三种红烧肉脂肪层脂肪含量、过氧化值、硫代巴比妥酸值和脂肪酸组成的变化。结果:三种工艺红烧肉制作过程中,肥肉层脂肪含量均显著下降(p<0.05),炖煮温度越高,脂肪含量下降越显著;POV值先增大后减小,在炖煮30 min达到最大值;TBA值在炖煮过程中显著增大(p<0.05);亚油酸(C18:2)、油酸(C18:1)、棕榈酸(C16:0)以及硬脂酸(C18:0)是五花肉脂肪中的主要脂肪酸,占总脂肪酸的90%以上,亚油酸(C18:2)含量显著下降,单不饱和脂肪酸含量上升。结论:三种工艺红烧肉制作过程中,脂肪含量下降、脂肪适度氧化、脂肪酸组成改变,红烧工艺对脂肪氧化和脂肪酸含量影响较大。     

速冻菜肴红烧肉的工艺研究

为解决速冻菜肴红烧肉的工业化生产,采用正交试验,研究了速冻红烧肉的原料配方与加工工艺参数对速冻红烧肉品质的影响。试验结果表明,速冻红烧肉最优配方为料酒10％、糖色8％、米醋2％、老抽5％（以肉重计）;最佳工艺参数为肉块焯水时间2min、上色时间2min、焖焙时间2h,焖焙时间对速冻红烧肉感官评价影响显著。     

红烧肉制作过程中脂肪氧化和脂肪酸组成的变化

脂肪氧化和脂肪酸组成变化对肉制品的营养和风味产生重要影响。研究红烧肉烹制全过程中原料、水焯后、炖煮1h、炖煮2h 4个关键工艺点中猪肉的基本物理化学指标、脂肪氧化和脂肪酸组成变化情况。结果表明：成品红烧肉水分含量和粗脂肪含量分别比原料肉下降18.17%和43.46%,烹饪损失率为25.04%;过氧化值(POV)在炖煮1h后达到峰值,随后又下降;硫代巴比妥酸值(TBA)在烹制过程中逐渐上升(P＜0.05);烹制过程使饱和脂肪酸(SFA)比例显著下降(P＜0.05),单不饱和脂肪酸(MUFA)比例显著上升(P＜0.05),不饱和脂肪酸与饱和脂肪酸比值(UFA/SFA)从1.38上升到2.34,提高了猪肉中油脂的营养价值。     

Effects of frying on polar material and free fatty acids in soybean oils

The purpose of this study was to investigate the quality deterioration of pressed soybean oil (PSBO), first grade solvent extracted soybean oil (FG‐SESBO) and third grade solvent extracted soybean oil (TG‐SESBO) with respect to time at 180 °C. It was found that there was a significant increase in total polar material (PM; P < 0.01) and free fatty acids (FFA; P < 0.05) in PSBO, FG‐SESBO and TG‐SESBO with increased time of frying. After forty‐five frying cycles, the final concentration of total PM was significantly higher in TG‐PSBO (30.39%) than in PSBO (21.10%) and FG‐SESBO (25.93%; P < 0.05). During frying cycles, the final acid value (AV) was significantly higher in PSBO (0.84 ± 0.02 mg KOH/g fat) than in TG‐SESBO (0.59 ± 0.01 mg KOH/g fat) and FG‐SESBO (0.56 ± 0.03 (mgKOH/g oil; P < 0.05). The content of saturated fatty acids in the three types of frying oils was significantly increased after forty‐five cycles of frying. However, even larger changes were observed in the content of unsaturated fatty acids, with decreases in C18:2, 9 c 12 c and C18:3, 9c 12c 15c and increase in C18:1, 9 c. The highest increasing slopes of PM and AV were observed in the TG‐SESBO.     

不同烹饪方式的牛里脊质构品质比较

分析不同烹饪方式对黄牛牛里脊质构参数、脂肪酸含量的影响。购买新鲜黄牛牛里脊,分为5等份,分别做生牛里脊、炖制、烤制、油煎、真空低温烹饪。对比烹饪方式对黄牛牛里脊持水力、pH、粗蛋白、粗脂肪、感官品质、色泽、质构参数、脂肪酸含量的影响。真空低温牛里脊的持水力、pH值、粗蛋白、粗脂肪分别为89.98%、6.12、23.69 mg/g、23.69%。牛里脊色泽、嫩度、多汁性、风味评分分别为8.86、8.49、8.84、8.62分,色泽参数L^*值、a^*值、b^*值、c^*值、h0值分别为45.15、4.12、14.82、15.39、15.39;质构参数硬度、粘性、弹性、咀嚼性、内聚力、剪切力分别为8.36 N、0.62 N·s、6.98 mm、42.68 N·s、0.42 N/cm2、25.39 N;饱和脂肪酸含量、不饱和脂肪酸含量均较高。真空低温牛里脊与炖制牛里脊、烤制牛里脊、油煎牛里脊持水力、pH、粗蛋白、粗脂肪、感官品质、色泽、质构参数、脂肪酸含量相比,具有统计学差异(p<0.05)。由上述结果可知,不同烹饪的牛里脊与生牛里脊相比,存在一定的微观结构、质构变化和营养物质改变,真空低温烹饪方式下黄牛牛里脊微观结构较为完整,对质构的影响较小,更好的保留脂肪酸等营养成分,符合对黄牛牛里脊的烹饪要求。     

The influence of frying medium degradation on fat uptake and texture of French fries

The purpose of the present investigation was to study the influence of the degree of degradation of different kinds of oils used as a frying medium on fat uptake and texture of frozen pre‐fried French fries. As has been found, the degradation degree of the frying medium depends on the kind of oil and processing time. Liquid hydrogenated rapeseed oil exhibited the best thermo‐oxidative stability among the oils under investigation. The kind of oil influenced fat uptake and the texture of French fries. The lowest fat uptake was observed with French fries fried in solid oil. Some correlations between fat uptake and changes in fatty acid content were found in the frying medium during frying. Fat absorption increased with increasing unsaturated fatty acids and decreasing saturated fatty acid content. The texture of French fries fried in hydrogenated oils was harder than that exhibited by French fries fried in liquid rapeseed oil. The hardness of French fries fried in liquid oils decreased during frying while the hardness of French fries fried in solid oil increased. Some correlations between the texture of French fries and iodine value and fatty acids content of frying media were found. The hardness of French fries increased with increasing content of saturated fatty acids and decreasing unsaturated fatty acids and trans isomer fatty acid content. Copyright © 2005 Society of Chemical Industry     

Effect of sampling fat location and cooking on fatty acid composition of beef steaks

To investigate the impact of sampling fat location and cooking on fatty acid composition of beef steaks, 21 raw steaks from crossbred steers were dissected to obtain outer (OSC) and inner subcutaneous fat (ISC), seam fat, marbling, and lean muscle. Twenty-one cooked steaks were dissected to obtain OSC, ISC, seam fat, surface and inner muscle. Trans-vaccenic acid and c9, t11-CLA percentages were lower (P < 0.05) in lean muscle than subcutaneous (s.c.) fat or marbling. Monounsaturated: saturated fatty acid ratios were lower (P < 0.05) in seam fat and marbling than s.c. fat or lean muscle. Linoleic and linolenic acid levels were highest in lean muscle and longer chain n−6 and n−3 fatty acids were only detected in lean muscle. Cooking did not change fatty acid composition dramatically except that n−6: n−3 ratio in s.c. and seam fat decreased after cooking (P < 0.05).     

Changes in the texture,microstructures, colour and volatile compounds of pork meat loins during superheated steam cooking

We evaluated changes in the texture, colour, microstructure and volatile compounds of pork loins after superheated steam (SHS) cooking at 120, 140, 160 or 180 °C for 5, 10, 15 and 20 min. Results showed that the texture changed significantly with heating temperature and time. Hardness increased significantly with increasing temperature above 140 °C. Scanning electron microscopy micrographs showed that cooked pork with SHS had more complete muscle fibre bundle structure than that of pork in HA. The L* value indicating colour was significantly increased during the early period and then decreased, whereas the a* and b* values showed a continuous increase. Ninety-five volatile compounds were identified in cooked pork from SHS by gas chromatography/mass spectrometry with solid-phase microextraction. The amount of volatile compounds increased during cooking and decreased as cooking time increased and was well retained at 140 °C. Considering those variations, samples cooked at 140 °C showed better quality attributes.     

Effects of deep‐fat frying temperature on antioxidant properties of whole wheat doughnuts

The total phenolic (TP) content, phenolic acid composition and in vitro antioxidant capacity of whole wheat doughnuts fried at 120–180 °C were determined to identify the effects of frying temperature. Significant differences (P < 0.05) in TP content were observed between doughnuts fried at different temperatures. The TP content of doughnuts decreased significantly when doughnuts were deep‐fat fried. The TP content of doughnuts increased with elevation with frying temperatures. These increases in TP content of doughnuts were also detected in the determination of individual phenolic compounds using HPLC. DPPH radical and iron‐chelating capacity of deep‐fat fried doughnuts exhibited increases with elevation of frying temperature from 120 to 180 °C. Deep‐fat frying at 120 °C lowered lipid peroxidation inhibition capacity of doughnuts prepared from both refined flour and whole‐grain meals and increased consistently with increased frying temperature from 120 to 180 °C. Moderate deep‐fat frying temperature would increase the content and activity of antioxidants of doughnuts.     

Water dynamics of turbot flesh during frying,boiling, and stewing processes and its relationship with color and texture properties: Low‐field NMR and MRI studies

Water dynamics in turbot flesh during frying, boiling and stewing was assessed by nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) techniques. Protons associated with different types of water were distinguished by T₂ relaxation spectra, and significant differences of water mobility were detected. Principle component analysis revealed a clear discrimination between samples of different cooking methods. MRI provided further visualization of internal information for turbot flesh during cooking. The linear regression analysis demonstrated a strong correlation between the NMR parameter A₂₃ and b* value (R² = .972) during frying process, A₂₃ and L* (R² = .963), T₂₂ and b* (R² = .991) during boiling process, T₂₂ and b* (R² = .883) during stewing process. Moreover, a good correlation was found between A₂₁ and cohesiveness (R² = .924) during the frying process, A₂₃ and resilience (R² = .879) during boiling process, as well as between A₂₃ and chewiness (R² = .946) during stewing process.

Practical applications

Water mobility and distribution can significantly affect turbot flesh physical and biochemical status leading to change the texture, color, tenderness and taste during cooking process. Therefore, it is very important to develop a fast, nondestructive method to monitor the water dynamics, reduce the cooking time, save energy and visualize the structure change of turbot flesh during cooking. In this study, a rapid and nondestructive NMR and MRI method were developed to analyze the water dynamics of turbot flesh during frying, boiling and stewing for the first time. The water states, distribution and mobility were analyzed by the NMR and MRI. Different cooking methods displayed different water dynamics in turbot flesh, which could be identified when NMR combined with chemometrics principal component analysis. The facile method by using both NMR and MRI for analysis of turbot flesh may have great potential for rapid and nondestructive analysis of other food processing.     

3种猪肉汤体系中蛋白质降解产物的比较研究

对3种不同烹制方法(水煮、炖煮和高压蒸煮)制得的猪肉和汤汁进行感官评定、总蛋白SDS-PAGE凝胶电泳以及总氮(TN)、水溶性氮(WSN)、非蛋白氮(NPN)和游离氨基酸(FAA)含量的比较研究。感官评定结果表明3种工艺分别为水煮30min,炖煮2h和高压蒸煮15min时,烹制所得肉和汤汁口感与风味最佳。总蛋白SDS-PAGE凝胶电泳图谱显示炖煮肉中大分子蛋白降解最为显著,炖煮肉汤中水溶性蛋白含量最高。水煮、炖煮和高压蒸煮使肉汤体系水溶性氮总量分别比鲜肉增加12%、24%和5%,非蛋白氮总量分别增加42%、59%和33%,游离氨基酸总量分别增加61%、78%和51%。炖煮猪肉的蛋白质降解程度比水煮和高压蒸煮高,且大部分蛋白质降解产物转移到汤汁中,赋予肉汤最优的营养和风味。     

Quality assessment of refined oil blends during repeated deep frying monitored by SPME–GC–EIMS,GC and chemometrics

The aim of this study was to investigate the effect of the refined palm oil addition (20%) on the fatty acid and sterol compositions of refined olive oil or refined soya bean oil and also to investigate the formation of total polar compounds and volatile compounds in these oil blends during fifty successive deep‐frying sessions of potato fries at 180 °C. The blend of refined olive oil and refined palm oil exhibited a higher chemical stability during the frying process than that of refined soya bean oil and refined palm oil. Indeed, the total polar compounds and volatile compounds formed, especially 2,4‐decadienal, were found to be relatively increased in the refined soya bean oil/refined palm oil blend reaching 36.50% and 46.70%, respectively, after fifty deep‐frying sessions. Moreover, the degradation of linoleic acid and β‐sitosterol was significantly (P < 0.05) observed for the refined soya bean oil/refined palm oil blend. The results have proven that the proper blending of monounsaturated refined olive oil with refined palm oil increases its stability and hence improves the quality of such olive oil during frying process.     

Reduction in hydroxymethylfurfural content in ‘churros’, a Spanish fried dough,by vacuum frying

This work explores the advantages of vacuum frying of ‘churros’, a Spanish dough pastry, compared to standard deep‐fat frying. Oil uptake, texture change, colour development, nonenzymatic browning and hydroxymethylfurfural (HMF) concentration were analysed at different frying conditions. The results obtained during vacuum frying at 100, 120 and 140 °C and 21 kPa were compared with those obtained at atmospheric pressure at 140 and 180 °C. For the same final water content, the vacuum fried ‘churros’ showed no significant differences in the fat uptake compared to those fried at atmospheric pressure (P > 0.05). However, the vacuum fried dough had a much crunchier texture. The evolution of the CIELab a* coordinate and the browning measurement at 280 nm show that vacuum frying is able to slow down the development of browning tones. Furthermore, products can be obtained with an HMF content <1 mg kg^?1 of dry dough.     

The effects of industrial pre-frying and domestic cooking methods on the nutritional compositions and fatty acid profiles of two different frozen breaded foods

This study was carried out to determine the effects of manufacturer pre-frying in olive and sunflower oil, as well as domestic cooking methods (deep-frying in olive and sunflower oil and baking) on the proximate compositions and fatty acid profiles of tuna pasties and ham nuggets. The pre-frying processes reduced moisture and carbohydrates and increased ash, fat and protein content in both pre-fried products. During cooking, the frying processes caused a reduction in moisture content and an increase in fat content in relation to pre-fried samples, while baking did not modify the proximate composition. The fatty acid profiles of products during both the pre-frying and frying processes became similar to those of the culinary fat used. Thus, the frying processes reduced the proportion of saturated fatty acids (SFA) and increased the proportion of monounsaturated fatty acids (MUFA) in the foods when olive oil was used, whereas increased the proportion of polyunsaturated fatty acids (PUFA) in products fried in sunflower oil. The fatty acid profiles of fried samples tended to be more similar to the frying fat than to the pre-frying fat, whereas the fatty acid profiles identified during the pre-frying process for baked products were not significantly modified. Thus, samples pre-fried in olive oil and subsequently baked showed the best proportion of fat content and PUFA/SFA, MUFA + PUFA/SFA and n-6/n-3 ratios of the tested products.     

油炸温度和时间对猪肉块品质的影响

本文研究了不同油炸温度和时间对猪肉块品质的影响,分析了150、165和180℃条件下油炸不同时间后猪肉块的色泽、硬度、水分含量、脂肪含量、蛋白质羰基含量、硫代巴比妥酸值(TBARS值)和挥发性醛类物质的变化情况。实验结果表明,油炸后猪肉块的亮度降低,红度和黄度升高;硬度在油炸过程中变化显著(p<0.05),150℃油炸470 s时达到最大值37.59 kg;150、165和180℃分别油炸470、330和230 s后猪肉块的水分含量减少了56.25%、52.82%和48.92%(p<0.05),高温短时油炸条件下水分损失较少;脂肪含量在150、165℃时随时间变化不显著,180℃油炸时随时间的延长显著增加(p<0.05);蛋白质羰基含量随油炸时间的延长而增大,180℃油炸150 s时猪肉块的蛋白质羰基含量为2.17 nmol/mg;TBARS值和己醛含量在油炸后迅速增大,之后呈现先减小后均大的趋势,180℃油炸150 s的TBARS值为0.71 mg MDA/kg;挥发性醛类物质中己醛与TBARS值相关性显著,150、180℃条件下的相关系数分别为0.962和0.997。180℃油炸150 s时的猪肉块具有金黄的色泽,硬度适中,脂肪和蛋白质氧化程度较小,具有较好的品质。     

Effects of fat replacement with a mixture of collagen and dietary fibre on small calibre fermented sausages

Effects of fat replacement on physicochemical, microbial and sensory properties of fermented sausages were determined after drying process and 4 weeks of storage. Fermented sausages were formulated with 20% pork back fat (control), and three reduced‐fat treatments were prepared by replacing 25%, 50%, and 75% of fat with a mixture of collagen, dietary fibre and ice (1:1:8). TBARS values of reduced‐fat treatments were significantly lower compared with control after drying (P ≤ 0.05). As fat replacing ratio increased, fat content decreased significantly (P ≤ 0.05), whereas moisture, protein and ash content increased significantly (P ≤ 0.05). There was no marked difference between the treatments in terms of microbial analysis, sensory colour, flavour, off‐flavour or overall acceptability (P > 0.05) during refrigerated storage. Therefore, replacing pork back fat with a mixture of collagen and dietary fibre in fermented sausages may contribute to reduce lipid oxidation and maintain sensory properties during storage.     

Changes of volatiles in soy sauce‐stewed pork during cold storage and reheating

Pork, soy sauce, and pork in soy sauce were cooked separately for 4 h; their volatiles were isolated, analysed and compared. Many of the volatiles reported to be present in pork or soy sauce were lost, and some volatiles identified in this research were generated from precursors in pork and soy sauce during cooking. Water‐boiled pork and soy sauce‐stewed pork were prepared and stored at 4 °C; they were reheated daily and stored again at 4 °C for 10 days. During storage the amount of compounds containing sulphur, such as dimethyl trisulphide and thialdine, was higher in the water‐boiled pork than in the soy sauce‐stewed pork. 3,5‐Dimethyl‐trans‐1,2,4‐trithiolane was found only in the soy sauce‐stewed pork. Significantly more aldehydes produced from lipid oxidation, such as hexanal, 2,4‐decadienal and 2‐undecenal, were present in the water‐boiled pork than in the soy sauce‐stewed pork during storage. These aldehydes reached a maximum quantity at day 6 of storage. In contrast, the soy sauce‐stewed pork contained more hexadecanal, octadecanal and 9‐octadecenal than the water‐boiled pork. © 2001 Society of Chemical Industry     

烹饪方式对鸡肉挥发性香气及质构特征的影响

分别以炒、炖、焖3种方法对鸡肉进行烹饪,比较烹饪方式对鸡肉挥发性香气、形态的影响。结果表明:烹饪后鸡肉的感官品质特性发生了显著变化,鲜肉挥发性成分中醛类物质显著高于醇类和烷烃类,烹饪后鸡肉中挥发性成分主要是醛类和烷烃类物质,醛类和醇类物质含量显著降低,降低程度大小顺序均为:炒焖炖;而烷烃类物质含量显著增加,增加程度大小顺序均为:炒焖炖,并且检测出几个新的高分子物质;烹饪后鸡肉的硬度、弹性、内聚性和咀嚼性均大幅度升高,3种烹饪方式中,炒能显著降低鸡肉硬度和咀嚼性,且弹性和内聚性较高;而焖具有增加鸡肉的硬度和咀嚼性,且降低弹性和内聚性的趋势。     

葱姜蒜混合物对炖煮猪肉感官品质、脂肪氧化及脂肪酸组成的影响

研究了不同添加量葱姜蒜混合物(onion-ginger-garlic,OGG)(5%、10%、15%)对炖煮猪肉感官品质(色泽、质地、滋味、香气)、基本理化指标(脂肪和水分)、脂肪氧化程度(过氧化值(POV)和硫代巴比妥酸值(TBA))及脂肪酸组成的影响。结果表明:OGG的添加能够提高炖煮猪肉的感官品质、改善肉的持水力,且随着OGG添加量的增大,炖煮猪肉的持水力显著提高(P0.05)。OGG能够抑制炖煮猪肉过氧化物及TBARS的产生,且添加量为15%的效果最显著(P0.05)。炖煮猪肉中添加OGG能显著抑制猪肉脂肪酸氧化,尤其是不饱和脂肪酸的氧化,且随着添加量的增加其抑制效果也明显提高。此外,OGG的添加还影响炖煮猪肉脂肪酸含量,添加OGG制得的炖煮猪肉,其单不饱和脂肪酸和多不饱和脂肪酸含量显著升高(P0.05),提高了不饱和脂肪酸(UFA)和饱和脂肪酸(SFA)的比例(P0.05),从而改善了猪肉的营养价值。