Lard uptake and its detection in selected food products deep-fried in lard

Analytical methods for the detection of both pork and lard in food products are in great demand for regulatory purposes. Means of identifying food products fried in lard has been investigated in this study. Four fat containing products namely, peanuts, tempeh (fermented soybean cake), chicken and beef were subjected to deep-fat frying using lard as the frying medium. Oils extracted from the control and fried samples were analyzed by gas liquid chromatography (GLC), high performance liquid chromatography (HPLC) and differential scanning calorimetry (DSC). In this way, changes in composition and thermal profiles during frying were examined. Results showed that palmitic acid enrichment factor (PAEF) calculated from GLC analysis of fatty acid methyl esters seems to be a useful parameter in determining lard contamination in all four fried products. With the triglycerol (TG) profiling by HPLC it was possible to detect lard in fried chicken and tempeh products while DSC cooling and heating traces were found to be useful for lard detection in fried tempeh, chicken and beef products.     

抗氧化剂对油炸肉制品品质及杂环胺形成的影响

系统全面分析GB 2760—2014《食品添加剂使用标准》允许添加至油炸肉制品使用的8 种抗氧化剂对3 种炸肉饼食用品质及杂环胺（heterocyclic amines,HAs）形成的影响。结果发现,不同抗氧化剂对不同种类肉制品的品质影响不同。竹叶提取物（extract of bamboo leaves,BL）、植酸钠（phytic acid,PA）、鼠尾草酸（carnosic acid,CA）、迷迭香酸（rosmarinci acid,RA）及茶多酚（tea polyphenols,TP）具有良好的保持3 种肉饼油炸过程中水分含量的能力,其能够降低油炸损失率,改善嫩度和质构特性等。不同抗氧化剂对炸肉饼中不同种类HAs形成的抑制活性有一定差异。炸鸡肉饼中,山梨酸钾（potassium sorbate,PS）对2-氨基-1-甲基-6-苯基咪唑并[4,5-b]吡啶（2-amino-1-methyl-6-phenylimidazo[4,5-b]-pyridine,PhIP）的抑制率相对最高（48%）,CA表现出对2-氨基-3,8-二甲基咪唑并[4,5-f]喹喔啉（2-amino-3,8-dimethyl-imidazo[4,5-f]-quinoxaline,8-MeIQx）相对最高的抑制率（56%）,PA、CA和PS显著降低炸鸡肉饼中总HAs含量（P＜0.05）;对于炸牛肉饼,CA对PhIP的抑制效果相对最佳,并且其与BL对8-MeIQx的抑制效果显著优于其他6?种抗氧化剂（P＜0.05）,CA、BL和PS显著抑制炸牛肉饼中总HAs的形成（P＜0.05）;炸猪肉饼中,BL对PhIP表现出相对最强的抑制活性（抑制率为64%）,8?种抗氧化剂均能显著抑制8-MeIQx和2-氨基-3,4,8-三甲基咪唑并[4,5-f]喹喔啉的形成（P＜0.05）,并且BL对总HAs表现出相对最佳的抑制效果,抑制率为49%。总体而言,BL、CA、PA、TP、RA及PS对油炸肉制品中HAs的形成表现出相对更优的抑制活性。     

Pore development in chicken meat during deep-fat frying

In this study, the effect frying oil temperature (FOT) and frying time on pore development was investigated during deep-fat frying (DFF) of chicken breast meat. The samples were sized to the following dimension: length×width×thickness=20×15×10 mm, and were fried at different FOTs (170°C, 180°C, and 190°C) in an industrial fryer for periods varying from 5 to 900 s. Oil uptake analysis was conducted by soxhlet extraction method with petroleum ether as the base extraction solvent. Pore development computation was based on the densities (bulk and apparent) measured after the end of each frying time with a fluid displacement pycnometry. The process variables significantly (P<0.01) influenced pore development in chicken meat during DFF. The final oil uptake was found to have influenced pore development. A goodness-of-fit test suggest linear model fitted well to the pore development and moisture loss experimental data while exponential model gave the best fit for pore development and oil uptake in chicken meat. A porosity of 0.28, 0.24 and 0.22 were found at FOT (170°C, 180°C, and 190°C), respectively.     

Frying oils with lower levels of saturated fatty acids induce less heterocyclic amine formation in meat floss (boiled,shredded and fried pork)

Heterocyclic amines (HAs) as potent mutagens are formed in meat floss which is a boiled, shredded and fried traditional meat product. In this study, effects of frying oils (lard, soybean oil and palm oil) on the formation of HAs in meat floss during frying have been investigated. The results showed that the contents of Norharman, Harman, AαC and MeAαC in meat floss that treated with lard and palm oil were higher than soybean oil which contained less saturated fatty acids (P < 0.05). The contents of total HAs in meat floss that treated with palm oil at 150 °C and 180 °C were significantly higher than that treated with soybean oil and lard (P < 0.05). In conclusion, meat floss treated with soybean oil at 120 °C, 150 °C and 180 °C contained lowest levels of HAs and soybean oil could be used as lard substitution to produce healthy meat floss.     

高压静电油炸对花生油及鸡胸肉食用品质的影响

为了研究高压静电油炸对花生油及鸡胸肉食用品质的影响,将鸡胸肉进行高压静电油炸(处理组:4 kV电压条件下,加入1 L花生油,油炸鸡胸肉120 s)和普通油炸(对照组:普通油炸锅,加入1 L花生油,油炸鸡胸肉120 s),测定花生油的过氧化值、酸价、丙二醛含量、色差以及鸡胸肉油炸失重率、质构和感官评定分值等指标。结果表明,高压静电油炸与普通油炸鸡胸肉后,花生油的酸价没有明显差异,但是高压静电油炸后的花生油过氧化值、丙二醛含量均比普通油炸的显著降低(p<0.05),油炸8批次鸡胸肉后,高压静电油炸鸡胸后的花生油亮度值为29.91,显著低于普通油炸鸡胸后花生油的亮度值(p<0.05);高压静电油炸的鸡胸肉失重率明显低于普通油炸后鸡胸肉的失重率(p<0.05),高压静电油炸鸡胸肉的感官评定分值较好。高压静电处理能提高油炸鸡胸肉的食用品质和产率,延缓花生油劣化。     

抗性淀粉对油炸调理鸡排品质特性的影响

针对油炸过程对调理肉制品质量与安全的影响问题,研究面糊中添加0%～40%的抗性淀粉对油炸调理鸡排品质特性（色泽、脆性、水分和油分含量、丙烯酰胺含量、微观结构及感官评价）的影响,以改善产品质量并实现低脂化。结果表明：添加20%～40%抗性淀粉的鸡排可获得良好的感官可接受性;添加20%抗性淀粉能显著降低油炸调理鸡排的含油量（P＜0.05）,提高油炸后外壳的黄度值,鸡排外壳表现出更好的金黄色,形成密实、连续的面糊微结构,改善外壳脆性,降低油炸过程中丙烯酰胺的生成量,提高产品安全性。因此,添加20%抗性淀粉能更好地降低油炸调理鸡排的含油量,提升产品质量。     

THE EFFECT OF EDIBLE FILM ON OIL UPTAKE AND MOISTURE RETENTION OF A DEEP-FAT FRIED POULTRY PRODUCT

The recent trend in reducing the fat content in fried foods is leading to the development of low-fat products using batter and breading formulations from protein and other hydrocolloids. The functionality of many of these edible ingredients on moisture retention and fat barrier properties during deep-fat frying is not clearly understood. The objective of this study is to evaluate the effectiveness of hydroxypropyl methylcellulose edible film coating on chicken balls for moisture retention and fat reduction during deep-fat frying. Two sizes (35 and 47 mm) of uncoated and coated chicken balls were fried in peanut oil at 175C for five different frying periods ranging from 30 to 180s for small and 30 to 300s for large balls. The moisture and fat content from the surface layer and core were determined. In comparison to the control, moisture retention up to 16.4% and fat reduction up to 33.7% were observed.     

The effects of various Chinese processing methods on the nutritional and safety properties of four kinds of meats

Chinese processed meat products are popular in the world, while different processing methods produce meats of different quality and safety. The aim of this work was to compare and evaluate the effects of seven Chinese processing methods (steaming, boiling, braising, pan-frying, frying, roasting and drying) on the nutritional and safety properties of four kinds of meats (beef, pork, chicken, duck). Comparing with the unprocessed raw meat, four kinds of meats treated with thermal processing displayed increased L^⁎ values, generally enhanced texture properties, decreased moisture contents, and increased protein contents. Among all the processing meats, the wet thermal processed meats exhibited relatively high total amino acid contents. Fatty acid contents showed the lowest value in boiled meats but relatively high values in fried, pan-fried and dried meats. For safety properties, thermal processing methods of pan-frying, frying and roasting caused mass formation of trans fatty acids and polycyclic aromatic hydrocarbons (PAHs). The highest PAHs contents were detected as 49.70 μg/kg in pan-fried beef, 18.18 μg/kg in fried pork, 11.02 μg/kg in roasted chicken and 15.24 μg/kg in fried duck, which were 14.34 times, 4.74 times, 7.50 times and 8.35 times of their corresponding blank control groups. When nutritional and safety properties are pursued, steaming and boiling are recommended for all the four kinds of meats. Besides, braising is also suitable for pork, while drying could also be used for chicken and duck.     

低场核磁共振结合主成分分析法在食用油脂品质分析中的应用

应用主成分分析法(PCA)对多种不同品质油脂样品的LF-NMR弛豫特性数据(T21、T22、T23、S21、S22、S23)进行了分析。研究表明,应用PCA可明显区分正常大豆油和棉籽油,但棕榈油和猪油样品分布范围有一定的重合;无论是轻度煎炸还是深度煎炸,不同种类的煎炸油脂在PCA得分图中能够明显分区;随煎炸时间的延长,油样在PCA得分图上的分布逐渐向左上方移动,四种油脂能够明显分为两类:棕榈油和猪油,大豆油和棉籽油;食用猪油与掺伪猪油样品在PCA得分图上能够明显区分,掺伪比例愈高,二者的区分效果愈好,试验验证正确。说明基于油脂的LF-NMR弛豫特性,结合主成分分析可实现对食用油脂种类、煎炸油程度及掺伪猪油的品质区分。     

菌体蛋白替代鸡胸肉的炸鸡块品质变化

为探究菌体蛋白在肉制品领域的应用可行性,使用菌体蛋白替代不同比例的鸡胸肉制作炸鸡块,并对获得的炸鸡块进行营养组成、烹饪损失、色泽、质构特性以及感官评价测试。结果表明：菌体蛋白替代20%～60%鸡胸肉制作的炸鸡块产品,蛋白含量在21.12 g～18.78/100 g,脂肪含量在9.98～10.48 g/100 g,膳食纤维含量在2.22～5.23 g/100 g。随着菌体蛋白比例增加,炸鸡块的烹饪损失由19.19%减小到16.28%,硬度由4.48 N升高到5.97 N,弹性呈现先升高后降低的趋势。菌体蛋白替代20%鸡胸肉的炸鸡块与无菌体蛋白的产品相比,营养组成差异小,嫩度无差异(p>0.05),但亮度(L^*67.60)增加,咀嚼性与弹性分别提高43.95%与17.95%(p<0.05),感官评价接受度良好。综上所述说明菌体蛋白可用于制备新型炸鸡块产品,研究能够为菌体蛋白作为动物蛋白替代的应用开发提供技术支持。     

预熟制对油炸猪肉丸品质的影响

探讨煮制、蒸制和微波3 种预熟制处理的加入对油炸猪肉丸品质的影响。以直接160 ℃油炸6 min的猪肉丸为对照,测定经过煮制、蒸制和微波预熟制加热处理10 min后160 ℃油炸2 min的猪肉丸的品质指标。结果表明：与对照组相比,煮制和微波预熟制显著影响油炸猪肉丸的色泽（P＜0.05）,蒸制处理对肉丸色泽影响不显著（P＞0.05）;不同预熟制处理对油炸猪肉丸的弹性和内聚性没有显著影响（P＞0.05）;微波预熟制后油炸猪肉丸的含水率和脂肪含量均显著下降（P＜0.05）,而煮制后油炸的猪肉丸含水率和脂肪含量均显著上升 （P＜0.05）,蒸制后油炸的猪肉丸含水率和脂肪含量变化不显著（P＞0.05）;经感官评定,煮制后油炸猪肉丸感官评分显著降低（P＜0.05）,蒸制和微波预熟制对油炸肉丸感官评分无显著影响（P＞0.05）。微波预熟制可用于生产低脂肪含量油炸制品。     

大豆营养仿肉制品的开发研究

大豆营养仿肉制品是以大豆蛋白为原料,辅以大豆植物油,添加调味料和香辛料,经过类似肉制品加工方法进行加工。但这类产品不采用畜禽肉为原料,不属于肉制品,只是模仿肉制品的组织结构并赋予肉制品的风味,按照肉制品来命名,如"大豆维也纳香肠"或"素维也纳香肠"、"大豆牛肉火腿"或"素牛肉火腿",产品具有高蛋白、不含动物脂肪、低胆固醇特点,以满足人们健康需求以及越来越多素食者的需要。     

EFFECTS OF DRY AND MOIST HEAT ON SELECTED HISTOLOGICAL CHARACTERISTICS OF BEEF SEMIMEMBRANOSUS MUSCLE

ABSTRACT— Samples of raw and heat-treated beef semimembranosus muscle were examined histologically to determine how deep-fat frying, oven roasting, oven braising and pressure braising to 70°C affected histological characteristics of the muscle. A panel of three persons used an ocular micrometer to measure muscle fiber width, observed color and type of connective tissue and distribution of fat and estimated quantity of connective tissue of 475 histological sections. Differences among heat treatments in muscle fiber width and relative proportion of straight and wavy connective tissue were not significant. However, there was a significantly (P<0.05) larger quantity of granular tissue in deep-fat fried, pressure braised, and oven braised samples than in oven roasted samples. Intact fat cell walls were observed in both raw and heated samples.     

烹制方法对猪肉脂质氧化和挥发性风味物质的作用研究

研究对比了4种烹制方法(煮制、烤制、微波及油炸制(大豆油、花生油和葵花油))对猪肉脂质氧化及挥发性风味成分的影响。结果表明:烹制能够促进猪肉的脂质氧化,经不同方式烹制后,熟制猪肉的过氧化值(POV)和硫代巴比妥酸值(TBA)显著增加(P0.05)。不同熟制猪肉之间脂质氧化程度存在显著性差异(P0.05),其中烤制猪肉的脂质氧化程度最高,其次为微波和水煮,而炸制猪肉的氧化程度最低。气相色谱-质谱(GC-MS)联用技术从熟制猪肉中共分离鉴定出68种挥发性风味成分,主要包括醛类、脂肪烃类、醇类、酮类、酯类等,总挥发性风味化合物含量在221.09(大豆油炸制猪肉)-1084.61 AU×106/g(煮制猪肉)之间。醛类是主要的化合物,占总挥发性风味成分的73.78(葵花油炸制猪肉)-78.79%(烤制猪肉),而己醛是最主要的醛类物质。TBA值与醛类、醇类及总挥发性风味物质呈显著正相关(p0.05),而POV值与挥发性风味物质的相关性不显著(p0.05)。主成分分析法(PCA)能够很好地区分经不同烹制方法得到的熟猪肉。     

Nutritional Effects of Fresh, Laboratory Heated, and Pressure Deep-Fry Fats

Cooking fats from a pressure deep-fat frying operation producing fried chicken, were compared with laboratory heated and fresh fats in the diets of animals. Included were corn oil (CO), peanut oil (PO), and partially hydrogenated soybean oil (HSBO). Weanling rats were fed diets containing 15% fat for 28 days. Laboratory heating reduced absorption of CO and PO, but not that of HSBO. Pressure deep-frying increased absorption of HSBO. Animals derived less metabolizable energy from diets containing heated or hydrogenated fats relative to fresh oil. Polar lipid fractions of liver changed due to heating. Pressure deep-frying with fats resulted in less deterioration than with laboratory heating, as shown by chemical analyses, coefficient of digestibility, and metabolizable energy studies.     

Proximal composition and fat type of three popular take-away meals

Random samples of three popular types of take-away meal (fish and chips, chicken chow mein and meat curry) were bought from various outlets in a town in the North of England. They were analysed for protein, sodium and amount and type of fat.
The fat content of the fish and chips was very high, and less high in the chow meins and curries. In all three types of meal, the fat was mainly saturated and mono-unsaturated, although in the fish and chip samples the saturated fraction was particularly high; traditionally they are fried in beef dripping.
Although the amount of polyunsaturated fatty acid (PUFA) is lower in products fried in oil, preliminary results from this study suggest that up to half of this may be in the trans -form; this is alleged to be no better than saturated fatty acid in effects on blood cholesterol (Gurr, 1986).
The study clearly indicates wide variation in both amount and type of fat within one meal type, and throws serious doubt on the feasibility of implementing meaningful nutritional labelling/information in take-away outlets.
The amount of sodium in the Chinese meals was particularly high.     

Effect of microwave pretreatment on mass transfer during deep-fat frying of chicken nugget

The effect of a microwave pretreatment at different time duration on the mass transfer of chicken nuggets during deep-fat frying was studied. Coated chicken nugget samples pretreated in a microwave oven for 1-2 min were fried at 160 °C for times ranging from 0 to 300 s to evaluate the mass transfer as compared to the samples without a microwave pretreatment. Microwave pretreatment had a significant effect on moisture loss and oil uptake of chicken nuggets during deep-fat frying.     

INSTITUTIONAL COOKERY OF RESTRUCTURED BEEF STEAKS

Restructured beef steaks were cooked under four institutional cooking methodologies: oven roasting, grill frying, deep fat frying and broiling. The samples were evaluated for fat and moisture contents, cooking loss and texture. Sensory panels evaluated the steaks for texture desirability, flavor desirability, appearance and overall palat-ability. Evaluations were repeated using breaded, restructured beef steaks cooked by the four institutional methods, with grilled unbreaded steaks included for comparison. Deep fat fried, breaded and unbreaded steaks were significantly lower in moisture and higher in fat than those cooked by any other methodology. No significant differences in juiciness, flavor desirability or overall palatability were found between the unbreaded broiled, oven roasted or grilled samples. Broiled and grilled steaks were preferred for texture in the unbreaded and breaded samples. The unbreaded, deep fat fried samples received the lowest scores for all sensory attributes. Breading significantly improved the juiciness, texture and overall palatability of the deep fat fried steaks. For both breaded and unbreaded samples, grill frying was the preferred method of preparation.     

Quality changes in chicken nuggets fried in oils with different degrees of hydrogenatation

Quality changes in chicken nuggets fried in different mixtures of hydrogenated and non-hydrogenated canola oils were studied. Colour, texture, oil and moisture contents of the chicken nugget samples fried at 190 °C for 30, 60, 90, 120, 180, 240 and 300 s were investigated. The proportions of hydrogenated to non-hydrogenated frying oils used in the study were 0%, 20%, 40%, 60%, 80% and 100%.Results indicate that increase in frying time resulted in decreased product lightness (L*) whereas redness (a*) and yellowness (b*) increased. The maximum load to puncture increased with increasing frying time. In addition, oil content increased slowly with frying time, and moisture content decreased as expected. Both frying times and oil types have significant effects on the quality parameters investigated. First-order kinetic equation was used to describe colour changes as well as oil and moisture contents of the samples. Oil and moisture contents had negative correlation relationship. With increasing degree of oil hydrogenation, the surface colour of the fried chicken nuggets samples were lighter, texture increased, oil and moisture contents decreased.     

Effect of local processing methods (boiling,frying and roasting) on the amino acid composition of four marine fishes commonly consumed in Nigeria

The effects of different processing methods on the amino acid contents of four marine fishes commonly consumed in Nigeria: Clupea harengus, Scomber scombrus, Trachurus trachurus and Urophycis tenuis were investigated. The samples were boiled, roasted over hot charcoal, or fried in any of four different oil types (palm oil, soybean oil, vegetable oil and groundnut oil). The total amino acids for all the fish samples ranged from 76.72 to 98.01 g/100 g protein and the total essential amino acids from 28.95 to 44.73 g/100 g protein. Frying reduced the total amino acid contents, with the lowest values obtained in samples fried in palm oil. Boiling and roasting increased the total amino acid contents, with the values higher in roasted than boiled samples. The percentage of essential amino acids reduced with processing in almost all samples, but the reduction was more pronounced in the fried samples. The raw, boiled and roasted samples had amino acid scores greater than 100%, while for the fried samples, the limiting amino acids were either leucine or threonine. The results showed that roasting and boiling had more desirable effects on the amino acid content of the fish samples.