Effect of different adsorbents on purification of used sunflower seed oil utilized for frying

The refining of used frying oils is of commercial and economic importance. The re-use of recovered oil could provide considerable savings to the food processors. In this study, 50 consecutive deep-fat fryings were done using 100-g potato samples in 1.5 l (initial) of sunflower seed oil at 170 °C. The refining of used sunflower seed oil was investigated by various adsorbent treatments. Six adsorbents, CaO, MgO, Mg ₂CO ₃, magnesium silicate, activated charcoal and bentonite, as well as an available natural earth (i.e. pekmez earth, CaCO ₃ containing special natural white soil) were studied. Pekmez earth, magnesium silicate (florisil) and bentonite exhibited the highest abilities in viscosity, free fatty acids (FFAs) reduction and colour recovery, respectively, among the adsorbents studied. Therefore, a mixture of 2% pekmez earth, 3% bentonite and 3% magnesium silicate was found to be the best combination. The quality parameters of used sunflower seed oil (FFA content, colour values and viscosity) were improved due to adsorbent mixture application.     

滤油粉对煎炸油处理效果的评价

针对市场上出现的滤油粉及其在煎炸油处理上的应用,对滤油粉处理过的3种煎炸油的酸值、过氧化值、碘值、吸光度和外观的变化进行测定。结果表明,经滤油粉处理后煎炸油的外观透亮,吸光度降低,酸值、碘值都有所降低,而过氧化值升高。研究表明滤油粉对煎炸油处理效果不佳,只能吸附炭化杂质。     

An oil dilution technique used in small-scale frying to reduce oil expenditure

An oil dilution technique was developed and it saved oil expenditure in doughnut frying by about 30% without any compromise in doughnut quality compared with standard small‐scale control frying. Doughnut quality as evaluated by a sensory panel and absorbed fat content measurements, also supported the main findings. In addition, either the oil density, acid value or alkaline contaminant materials can be effectively used to monitor oil quality changes during frying.     

食用油煎炸过程中影响极性成分生成因素的研究

食用油在煎炸过程中会发生劣变,产生的极性化合物对人体健康有不良影响。对食用油煎炸过程中影响极性成分生成的因素进行了研究,结果表明,极性成分的含量随着煎炸时间的延长、煎炸温度的升高而增加,同时还与煎炸油品种和煎炸过程中新油的添加方式相关。     

Impact of oil used by the frying industry on population fat intake

Chronic multifactorial diet related diseases are the major causes of death and illness worldwide. The amount and composition of fat in the diet is an important determinant of the pathobiology of many of these conditions. In the current review the associations between dietary fat and disease risk will be considered. Mean population fat intakes will be compared with dietary recommendations aimed at reducing the population burden of disease and the main sources of fat in the adult and childhood diet will be given. An assessment will be made of the principal vegetable oil sources used in the manufacture of processed foods, in particular fried foods, with particular reference to the rheological and nutritional justification for their use. The impact of the more widespread use of alternative oil sources with improved fatty acid profiles, on the fat composition of fried foods and the overall diet will be presented, demonstrating that such apparently focussed approaches could potentially result in a significant impact on population fat intake and potentially overall chronic disease burden.     

The recovery of used sunflower seed oil utilized in repeated deep-fat frying process

In this study, 50 consecutive deep-fat fryings were done by frying potato samples, each weighing 100 g, in sunflower seed oil at 170 °C. Significant chemical and physical changes in sunflower seed oil were observed during frying. A number of official methods were used to evaluate its adsorption abilities including free fatty acids (FFA), peroxide value (PV), conjugated dienes at 232 nm, secondary oxidation products at 270 nm and specific heat value determination. These parameters were determined in oil samples taken after each of the ten fryings before and after adsorbent treatment. A mixture of 2% pekmez earth, 3% bentonite, and 3% magnesium silicate was used as the adsorbent mixture. The FFA content of oil increased from 0.17 to 0.29% during frying. The use of adsorbents reduced FFA content of the used oil to 0.13%, i.e., a value below the FFA content of fresh oil (0.17%). Peroxide values decreased during frying because of decomposition of peroxides at high temperatures. A significant reduction was obtained in peroxide and conjugated diene values (K₂₃₂ value) due to the adsorbent treatment. However, the treatment increased the amount of secondary oxidation products (K₂₇₀ value). The specific heats of untreated used oil were higher than specific heats of adsorbent treated used oil over the entire frying process.     

水产裹涂食品中油脂与油炸过程中煎炸用油品质变化的相关性研究

通过模拟油炸水产裹涂食品的生产工艺,对在高温油炸条件下油炸用棕榈油及水产裹涂食品油脂品质变化的相关性进行了研究.结果表明:煎炸用油和食品残油的酸价、羰基价都随油炸时间延长而增大,食品油脂的酸价和羰基价较油炸用油的酸价和羰基价变化速率快,而油炸用油的相对粘度较食品油脂的相对粘度变化速率快,因此应以食品中油脂的劣变程度决定煎炸用油的使用时间.     

介电常数监测天然抗氧化剂抑制煎炸棕榈油劣变

采用介电常数法监测茶多酚(TP)、植酸(PA)、维生素E(VE)抑制煎炸棕榈油劣变效果。测定在3种天然抗氧化剂作用下,煎炸棕榈油过氧化值、酸价、羰基价、p-茴香胺值等化学参数与介电常数值的变化,分析了介电常数值与化学参数值之间的相关性,并进行天然抗氧化剂复合配方的优化。结果表明:介电常数与四种化学参数之间显著相关,可以取代4种化学品质参数衡量煎炸棕榈油品质的劣变,以介电常数为指标得到天然抗氧化剂复配最佳组合为:茶多酚0.04 g/100 g,植酸0.016 g/100 g,维生素E 0.8 g/100 g。     

Kinetics of selective adsorption of impurities from a crude vegetable oil in hexane to activated earths and carbons

In this study, the selective removal of several impurities (chlorophylls and pheophytins, carotenoids, free fatty acids and oxidation products) from a solution of crude olive residue oil in n-hexane (miscella) by batch adsorption to different materials was investigated. The following adsorbents were tested: activated diatomaceous earths, powdered and granulated activated carbons. For the majority of the adsorbents used, both Freundlich and Langmuir isotherm models showed a good fit to the adsorption of pigments, free fatty acids (FFA), conjugated hydroperoxides (HP), and final oxidation products (FOP). Sigmoid profiles were observed for the adsorption of chlorophylls, carotenoids, and FOP to the 20-60 mesh carbon, suggesting the presence of pores in the intermediate range (2-50 nm). The FFA isotherm adsorption to the 8-20 mesh carbon can be explained by a multilayer adsorption phenomenon. On the basis of the estimated values for affinity and separation factors, the selective adsorption occurred in the following order for every adsorbent tested: chlorophylls and pheophytins>carotenoids>hydroperoxides>final oxidation products>free fatty acids. The highest adsorption efficiency was observed for the powdered activated carbon.     

从天然维生素E生产渣油中提取植物甾醇皂化工艺的研究

以脱臭馏出物生产天然维生素E及甾醇后的副产物渣油为原料,采用皂化工艺将渣油中的甾醇酯转化为植物甾醇,再用结晶的方法提取其中的植物甾醇。以提取的植物甾醇成品中甾醇含量为指标,采用单因素实验和正交实验优化的皂化工艺参数为:碱的质量浓度0.08g/mL,反应介质与渣油质量比0.3∶1,皂化时间3h,皂化温度80℃。     

Change in colour and rheological behaviour of sunflower seed oil during frying and after adsorbent treatment of used oil

Improvement in colour and viscosity of used sunflower seed oil was studied because the reuse of recovered oil could provide considerable savings to food processors. In this study, 50 consecutive deep-fat fryings were done by using potato samples in sunflower seed oil at 170 °C. Significant changes in sunflower seed oil were observed during frying. Change in viscosity and Hunter colour parameters were investigated. These parameters were determined on oil samples taken periodically during frying, and after adsorbent treatment. A predetermined optimum adsorbent mixture (2% pekmez earth, 3% bentonite and 3% magnesium silicate by weight) was applied for colour and viscosity recovery of used oil. Both the adsorbent-treated and untreated used oils showed Newtonian behaviour. Significant increase in oil viscosity was observed during frying. Frying caused a decrease in Hunter L value and an increase in a, b and TCD values of used oil samples. Adsorbents improved the Hunter L, a and b values significantly as well as TCD values, but not the viscosity of the used oil. All the Hunter parameters and TCD followed zero order reaction kinetics. Good agreement was observed between calculated and measured data (r=0.986–0.996).     

Recovery of used frying oils with adsorbent combinations: refrying and frequent oil replenishment

Treatment of used frying oils with adsorbent combinations may improve the quality of fried foods and extend the frying life of oil. Two selected combinations of four commonly used filter aids: Britesorb (Br), Hubersorb 600 (HB), Frypowder (Fr), and Magnesol (Ma) were used to recover used frying oils by vacuum filtration. The effectiveness of the adsorbent treatments were evaluated by refrying chicken fritters and breasts in the recovered used oil. After 32 h continuous frying, the parameters of treated oil subjected to adsorbent combinations F (3% HB+3% Ma+2% Fr) and B (2% HB+2% Ma+3% Br), were reduced as follows: 61.9 and 59.7%, 38.0 and 11.3%, 25.2 and 19.5%, and 9.4 and 3.5% for free fatty acids (FFA), total polar component (TPC), Foodoil Sensor (FOS) reading, and color differences (ΔE), respectively, compared to the untreated used oil. After daily treatment for 4 days, the filter aid combination F reduced the final values of FFA, TPC, FOS and color differences by 64.2, 19.1, 32.6 and 4.4%, respectively, compared to the untreated control. These adsorbent combinations may be useful in extending the life of frying oils.     

油炸机液压油与油炸油过滤系统的优化设计

阐述了油炸机液压油与油炸油的过滤现状与不足,提出了油炸机液压油与油炸油过滤系统改进设计方案,着重介绍了提高滤油精度的离心分离式滤油器的工作原理、结构特点。经实际应用,离心分离式滤油技术具有滤油精度高,构造简单,成本较低的特点。     

大豆油高温煎炸质变过程的研究

大豆油经高温间断煎炸,取样进行感官分析和理化指标测定,研究各理化指标在煎炸过程中的变化规律和彼此之间的相关关系。结果表明,油脂在间断煎炸13 h后就不能再继续使用了;羰基值是食用油煎炸过程中的卫生标准中最易超出的指标;油样运动黏度、过氧化值、羰基值以及极性组分含量与煎炸时间之间存在极显著的方程关系;运动黏度、酸值、过氧化值、羰基值和极性组分含量之间存在极显著的相关关系。     

Antioxidative effectiveness of some natural antioxidants in sunflower oil

Sunflower oil has been oxidized at 25 and 100°C in the presence and in the absence of 0.01,0.02 and 0.05% 3,4-dihydroxybenzoic acid, caffeic acid, esculetin and fraxetin. 3,4-Dihydroxybenzoic acid shows no antioxidative activity at either temperature. Esculezin possesses a relatively low effectiveness at 100°C (stabilization factorF=1.3 for 0.05% esculetin), and at 25°C it does not improve the oxidative stability. Sunflower oil is more easy to stabilize at 100°C:F=3.0 for 0.05% fraxetin, andF=1.9 for 0.05% caffeic acid. Native sunflower oil is much more difficult to stabilize than are its kinetically pure triacylglycerols.     

天然抗氧化剂在大豆油脂中抗氧化活性的研究

研究了3种常见的天然抗氧化剂茶多酚、迷迭香、番茄红素对大豆油的抗氧化效果,并通过复配和添加柠檬酸作为增效剂组合出5组复合抗氧化剂,通过考察过氧化值的变化趋势得到抗氧化效果最佳的复合天然抗氧化剂为茶多酚+迷迭香+柠檬酸.     

Authentication of edible vegetable oils adulterated with used frying oil by Fourier Transform Infrared Spectroscopy

The application of Fourier Transform Infrared (FTIR) Spectroscopy to authenticate edible vegetable oils (corn, peanut, rapeseed and soybean oil) adulterated with used frying oil was introduced in this paper. The FTIR spectrum of oil was divided into 22 regions which corresponded to the constituents and molecular structures of vegetable oils. Samples of calibration set were classified into four categories for corn and peanut oils and five categories for rapeseed and soybean oils by cluster analysis. Qualitative analysis of validation set was obtained by discriminant analysis. Area ratio between absorption band 19 and 20 and wavenumber shift of band 19 were treated by linear regression for quantitative analysis. For four adulteration types, LODs of area ratio were 6.6%, 7.2%, 5.5%, 3.6% and wavenumber shift were 8.1%, 9.0%, 6.9%, 5.6%, respectively. The proposed methodology is a useful tool to authenticate the edible vegetable oils adulterated with used frying oil.     

A study on the effects of salt and pepper on palm oil used as a frying medium

Chips of yam (Dioscorea rotunda) were fried in palm oil heated to 150°C prior to frying as follows: (a) palm oil without ingredients as control, (b) palm oil with 1% pepper (Capsicum annum), and (c) palm oil with 1% salt. The qualities of the oil in the frying medium and the oil absorbed by the fried yam were investigated for 10 fryings. The amount of carotenes in the oil/ingredient mixtures, both in the frying medium and the yam extract, was less than in the control. The peroxide values of samples in the frying media did not indicate either a pro-oxidant or antioxidant role for the ingredients. In samples of oil absorbed by the yam, the salt gave exceedingly high peroxide values but in the pepper samples, peroxides were not detected in six out of 10 fryings. However, high p-anisidine values of samples in the medium and yam extract have put into question the reported role of pepper as an antioxidant. Thus, pepper encouraged the accumulation of secondary rather than primary oxidation products in the oil.     

两种豆制品厂煎炸油净化方法效果的比较研究

本文对两种不同的豆制品厂煎炸油净化方法对煎炸油品质的影响进行了研究,选择了两家分别采用自然沉降净化法和加水净化法的企业,再选择两种相同的产品,在工厂条件下对煎炸油的酸价、羰基价和极性物质指标进行研究。研究结果显示两种煎炸油净化方法对煎炸油品质具有显著影响。