Effects of egg yolk powder addition to the flour dough on the lipid oxidation development during frying

Effects of egg yolk powder added to the dough on the oxidation of frying oil and lipid of fried products were studied. Flour dough containing egg yolk at 0, 3.53, 6.73, and 9.66/100 g was fried in 180 °C sunflower oil for 1.5 min, and 55 fryings were performed. Lipid damage was determined by free fatty acids (FFA), conjugated dienoic acids (CDA), and polar compounds contents, and p-anisidine values (PAV). Phospholipid (PL) classes were determined by high performance liquid chromatography. PL was not detected in frying oil and fried products without egg yolk, while the first batch of fried products added with egg yolk at 3.53, 6.73, and 9.66 in 100 g of the dough contained total PL at 3.73, 7.93, and 8.98 mg/g, respectively. Contents of PL classes tended to increase in the products fried in the oil performing more fryings. As the number of fryings of oil increased, FFA, CDA, and polar compounds contents and PAV of frying oil increased. Addition of egg yolk to the dough significantly decreased CDA and polar compounds contents and PAV of frying oil, but it increased FFA values. Lipid of fried products showed the same tendency in CDA contents and PAV. The results clearly indicate that egg yolk powder improved the oxidative stability of frying oil during frying, possibly due to PL.     

Oxidative Stability of Soybean and Sesame Oil Mixture during Frying of Flour Dough

ABSTRACT: Effects of roasted sesame seed oil on the oxidative stability of soybean oil during frying of flour dough at 160 °C were studied by determining fatty acid composition and conjugated dienoic acid (CDA), p -anisidine (PA), and free fatty acid (FFA) values. Concentration of sesame oil in frying oil was 0%, 10%, 20%, or 30% (v/v). Tocopherols and lignan compounds in the frying oil were also determined by high-performance liquid chromatography. As the number of fryings performed by the oil increased, linolenic acid content in frying oil decreased, and the decreasing rate was lower in frying oil containing sesame oil than in the oil containing no sesame oil. CDA and FFA values of frying oil increased during frying and their relative values to the initial value were lower in frying oil containing sesame oil than in the oil containing no sesame oil. This indicates that the addition of sesame oil improved thermooxidative stability of frying oil, possibly due to the presence of lignan compounds in sesame oil. Tocopherols and lignan compounds in frying oil decreased during frying. As the amount of sesame oil in frying oil increased, degradation of tocopherols increased and lignan compounds degradation decreased. Tocopherols were suggested to protect lignan compounds in sesame oil from decomposition during frying.     

Effects of Sesame Oil Addition to Soybean Oil During Frying on the Lipid Oxidative Stability and Antioxidants Contents of the Fried Products During Storage in the Dark

ABSTRACT: Effects of sesame oil addition to soybean oil during frying on the lipid oxidative stability and antioxidants contents of fried products during storage in the dark were studied. Flour dough pieces (2 cm × 2 cm × 0.1 cm) were fried at 160 °C for 1 min in sesame oil-added soybean oil. Concentrations of sesame oil in the frying oil were 0%, 10%, and 20% by volume. Fried products were put into a glass bottle, and the bottles were tightly sealed and stored at 60 °C in the dark for 18 d. Lipid oxidation of fried products was determined by fatty acid composition changes and conjugated dienoic acid (CDA) and p -anisidine (PA) values. Tocopherols and lignan compounds in the fried products were determined by high-performance liquid chromatography. Relative content of linolenic acid decreased, and CDA and PA values increased during storage of the fried products in the dark. Fatty acid composition change and CDA and PA values during storage were lower in the products fried in sesame oil-added soybean oil than in the products fried in soybean oil without sesame oil. The results clearly showed that addition of roasted sesame oil to soybean oil at 10% and 20% during frying decreased the lipid oxidation of fried products during storage in the dark for 18 d by extension of induction period and decrease in decomposition of oxidized lipids. Fried products contained 134 to 267 ppm tocopherols and 0 to 148 ppm lignans before storage; however, their contents decreased during storage in the dark. Lignan compounds were more stable than tocopherols, and the rate of tocopherols degradation was lower in the products fried in sesame oil-added soybean oil than in the products fried in soybean oil without sesame oil, which could be because of protection of tocopherols from degradation by lignan compounds.     

食用植物油煎炸过程中的品质变化北大核心CSCD

利用花生油、大豆油、调和油、棕榈油4种食用植物油作为煎炸油对豆腐、裹粉鸡柳、油条3种食材进行煎炸,研究煎炸时间对煎炸油极性组分含量及羰基值的影响,确定煎炸油时间预警点,同时研究了不同煎炸油品种、不同食材对煎炸油极性组分含量的影响。结果表明:极性组分含量、羰基值均与煎炸时间呈正相关(r_(极性组分)=0.809,r_(羰基值)=0.859,P=0.000);煎炸6~11 h煎炸油极性组分含量均值从初始的11.85%增至20.96%,最大值为34.10%,可作为煎炸油质量不达标的时间预警点;煎炸12 h,极性组分含量从低到高依次为花生油、棕榈油、调和油、大豆油,含量分别为21.1%、24.1%、26.8%、27.8%,豆腐、裹粉鸡柳、油条煎炸油中极性组分含量分别为17.7%、25.0%、32.2%;煎炸18 h,极性组分含量增大程度由低到高为棕榈油/调和油、大豆油、花生油,煎炸食材用油为豆腐煎炸油、裹粉鸡柳煎炸油、油条煎炸油。     

Effects of the Number of Fryings on Pigment Stability in Frying Oil and Fried Dough Containing Spinach Powder

ABSTRACT Chlorophylls and carotenoids in dough containing added spinach powder and fried, were determined by high performance liquid chromatography and spectrophotometry, respectively. Sixty-one batches of flour dough were fried for 1 min every 20 min in 160 °C soybean oil. Chlorophyll was not detected in the oil during frying. Carotene contents, however, increased with the number of fryings. Chlorophyll contents in the dough fried in soybean oil decreased with more fryings, while there was little difference in carotenoid contents. The results showed that only carotenoids diffused out of the dough in the previous frying could contribute to the pigment contents in the fried dough of the next batch.     

High-Temperature Natural Antioxidant Improves Soy Oil for Frying

ABSTRACT:  The objectives of this study were to determine the frying stability of soybean oil (SBO) treated with a natural citric acid-based antioxidant, EPT-OILShield™ able to withstand high temperatures and to establish the oxidative stability of food fried in the treated oil. Soybean oil with 0.05% and 0.5% EPT-OILShield and an untreated control SBO were used for intermittent batch frying of tortilla chips at 180 °C for up to 65 h. Oil frying stability was measured by free fatty acids (FFA) and total polar compounds (TPC). Chips were aged for up to 4 mo at 25 °C and evaluated for rancid flavor by a 15-member, trained, experienced analytical sensory panel and for hexanal content as an indicator of oxidation. Oil with 0.05% EPT-OILShield had significantly less FFA and TPC than the control. The effect of EPT-OILShield was apparently retained in aged chips because hexanal levels were significantly lower in chips fried in oil with 0.05% EPT-OILShield than in chips fried in the control. Tortilla chips fried in the control were rancid after 2 mo at 25 °C at sampling times evaluated from 25 to 65 h; however, chips fried in oil with 0.05% EPT-OILShield and used for 65 h were described as only slightly rancid after 4 mo. Gamma tocopherol levels were significantly higher in the chips fried in the oil with 0.05% EPT-OILShield than in the control, helping to inhibit oxidation in the tortilla chips during storage.     

Effects of Carrot Powder in Dough on the Lipid Oxidation and Carotene Content of Fried Dough during Storage in the Dark

ABSTRACT: Lipid oxidation and carotene content changes in fried dough containing carrot powder during storage at 60°C in the dark were studied. Flour dough containing carrot powder at 0%, 10%, 20%, or 30% was fried in 160°C soybean oil and stored in a 60°C incubator in the dark for 12 d. As storage time of the fried dough increased, conjugated dienoic acids and β-anisidine values of the fried dough increased. Addition of carrot to the dough lowered CDA and PAV of fried dough during storage and improved the lipid oxidative stability of the fried dough in the dark. Carotenes in the fried dough containing carrot powder were decomposed during storage, and faster decomposition rate was found in the dough containing less carrot powder.     

棕榈油和大豆油在油条煎炸过程中品质变化研究

以不同熔点棕榈油和棕榈油―大豆油混合油为原料,以大豆油作对照,通过比较油条外观、口感,筛选出适于煎炸油条的棕榈油,再进一步通过测定油条煎炸过程中油脂样品游离脂肪酸(FFA)、过氧化值(PV)、色泽、极性值(PC)、羰基价(COV)等指标,研究两种油在油条煎炸过程中品质变化情况。研究结果表明,熔点14℃棕榈液油和大豆油都适于煎炸油条,且棕榈液油在煎炸过程中具有比大豆油更好氧化稳定性,仅是其游离脂肪酸(FFA)和色泽上升速率快于大豆油。总的来说,两种油在满足煎炸油质量要求前提下,同等数量棕榈油可比大豆油煎炸更多油条。     

Oxidative stability of fried dough from rice flour containing rice bran powder during storage

The aim of this study was to evaluate the efficiency of rice bran powder on lipid peroxidation inhibition of fried dough from rice flour during storage. Rice flour dough containing rice bran powder at 5, 10 and 15 g rice bran powder/100 g mixed rice flour were fried in soybean oil at 160 °C for 1 min and stored in dark at 60 °C for 10 days. Lipid peroxidation of fried dough was determined by change of fatty acid compositions, oxygen absorption in vial headspace, lipid hydroperoxides, TBA values including decreasing tocopherol and gamma-oryzanol contents during storage. Polyunsaturated fatty acid decreased rapidly in fried dough without rice bran powder, while an increase of oxygen absorption in vial headspace, lipid hydroperoxide and TBA values were significantly lower (p?0.05) in fried dough containing rice bran powder. In addition, tocopherol degradation was significantly lower in fried dough containing rice bran powder during storage (p?0.05). However, there was no significant difference in gamma-oryzanol contents among fried dough during storage (p>0.05). These results demonstrated that rice bran powder shows the antioxidative effects on fried dough during storage.     

Lipid Oxidation and Carotenoids Content in Frying Oil and Fried Dough Containing Carrot Powder

ABSTRACT: Lipid oxidation and carotenoids in frying oil and carrot-added dough during frying were studied. Flour dough containing carrot powder was sheeted at 0.1 cm thickness and was then cut to squares to be fried. Each frying was performed in 160°C soybean oil for 1 min and repeated every 20 min for 20 h. Carrot in the dough decreased significantly the oxidative stability of frying oil and fried dough (p < 0.05). Carotenoid content in frying oil increased as frying was repeated due to dissolution of carotenoids from the dough containing carrot; however, there was no significant difference in carotenoid content among the dough fried in the oil with different number of fryings.     

Acrylamide formation in different batter formulations during microwave frying

Acrylamide, a probable human carcinogen, is found to be formed in a wide range of fried foods. In this study, the effects of microwave frying on acrylamide formation in the coating part of chicken were investigated. It was also aimed to determine the effects of various flour types (soy, chickpea and rice flour) in batter formulations on the acrylamide formation and on the color of fried chicken. Usage of all flour types except soy flour resulted in approximately the same moisture content and color development after 1.5 min of microwave frying. Acrylamide contents of batter parts of 1.5 min microwave fried samples having different flours were similar. Microwave frying provided lower acrylamide content and lighter color as compared to those fried conventionally for 5 min for all types of flours. This reduction in acrylamide level was the highest (34.5%) for rice flour containing batter.     

栀子果油煎炸过程中的品质变化及对油条和薯条的感官影响

为了探究栀子果油煎炸过程中的品质变化,本文选择薯条和油条两种代表性煎炸食材,将栀子果油在煎炸20h内每隔2h的酸价、羰基价、过氧化值和极性组分与大豆油、棕榈油在同等条件下煎炸的理化指标进行比较,结果表明：棕榈油煎炸后的品质较高,栀子果油和大豆油比较相似,栀子果油可以作为煎炸油。但栀子果油连续煎炸12 h时极性组分超过国家现有煎炸油的卫生标准,因此其连续煎炸时间不能超过12 h。同时对1、10、20h煎炸出来的油条和薯条进行感官评价,结果表明：煎炸食材相同时,三种食用油的感官评分无显著性差异（P>0.05）,说明栀子果油对油条和薯条的品质无不良影响,适合作为煎炸油。     

Effects of microwave frying and different flour types addition on the microstructure of batter coatings

In this study, the influences of microwave frying and various flour types on microstructure of batter coatings were investigated. Control batter formulation contained only wheat and corn flour. To determine the effects of different flour types, 30% of the corn and wheat flour mix was replaced with chickpea, rice or soy flours. Frying was performed in microwave oven at 365 W (70%) power level for 1.5 min after bringing the oil temperature to 180 ± 1 °C. Samples were also fried in a conventional fryer at 180 °C for 1.5 and 5.0 min for comparison. Microwave fried samples had higher specific bulk volume and porosity values and also smoother inner surface as compared to conventionally fried samples. Porosity values of different batter formulations were in the range of 0.425–0.484 in 1.5 min microwave fried chicken samples and 0.348–0.392 in 5.0 min conventionally fried ones. Microwave fried samples had comparable or lower hardness values than the conventionally fried ones depending on the flour type used in batter formulation. Microstructure of fried batter was different for different batter formulations. Microwave fried control and chickpea flour containing batter provided formation of larger gas cells on the outer surface. Soy flour containing batter resulted in smallest size gas cells for both frying methods.     

Effects of sesamol, sesamin, and sesamolin extracted from roasted sesame oil on the thermal oxidation of methyl linoleate

This study investigated the effects of lignan compounds extracted from roasted sesame oil, which were sesamol, sesamin, and sesamolin, on oxidation of methyl linoleate (ML) during heating. These compounds were added at 500 or 1000 mg/kg to ML, and α-tocopherol was used as a reference antioxidant. The ML added with lignans or α-tocopherol was heated at 180 °C for 60 min. Thermal oxidation of ML was evaluated by conjugated dienoic acid (CDA) contents, p-anisidine value (PAV), and ML retention. Contents changes of lignan compounds or α-tocopherol in ML during heating were monitored by high-performance liquid chromatography. CDA contents and PAV of samples increased and ML decreased with heating time at 180 °C. Samples added with lignan compounds showed lower CDA contents and PAV but higher ML retention than samples without lignan compounds. The antioxidant activity of sesame oil lignan compounds in ML oxidation during heating tended to be higher than that of α-tocopherol. The contents of lignan compounds in samples decreased with heating time due to their degradation, but the degradation rates were lower than that of α-tocopherol. This study suggested that sesame oil lignan compounds be used as antioxidants in oil at high temperatures for deep-fat frying due to their higher effectiveness and stability than α-tocopherol.     

Characteristics and oil absorption of deep‐fat fried dough prepared from ball‐milled wheat flour

BACKGROUND: High levels of oil in fried products has been recognized as causing health problems. The formation of microstructure during frying is one factor that influences oil absorption. Above the glass transition temperature (T_g), the physical properties of a polymer influences the formation of structure. The ball‐milling process changes the physicochemical properties of wheat flour constituents. The present study investigated the effects of physicochemical changes in wheat flour by the ball‐milling process on structure formation and oil absorption in wheat flour dough model. RESULTS: Dough samples were made from wheat flour that had been ball‐milled for 0 to 10 h and then fried in frying oil at 150 °C for 1–7 min. Thermal properties of wheat flour, structure alteration, and textural properties of fried samples were evaluated. As compared with samples made of non‐milled flour, samples made from milled flour had smaller pores and higher oil absorption. The fracture force of a fried sample prepared from non‐milled flour was lower than that of a sample prepared from milled flour. CONCLUSION: Ball‐milling affected the microstructure formation in fried wheat flour dough, and subsequently oil absorption. The crispness of a sample prepared from non‐milled wheat flour is higher than that of a sample prepared from ball‐milled wheat flour. This may be due not only to a plasticization effect, but may also be dependent on microstructure. Copyright © 2008 Society of Chemical Industry     

大豆油煎炸过程理化指标与煎炸时间相关性研究

针对食用植物油煎炸过程中理化指标是否可有效反映煎炸油品品质变化这一问题,以大豆油为煎炸油,薯条和鸡排为煎炸物质进行煎炸实验。随煎炸时间延长取不同程度煎炸油检测,研究酸值、羰基值、极性组分、p-茴香胺值、过氧化值和总氧化值等理化指标与煎炸时间相关性。结果表明:所研究理化指标中酸值、羰基值和极性组分3项指标与煎炸时间相关性较好,可有效反映油品变坏程度,p-茴香胺值、过氧化值和总氧化值相关性较差。     

Retention and distribution of natural antioxidants (α-tocopherol, polyphenols and terpenic acids) after shallow frying of vegetables in virgin olive oil

Potatoes, green peppers, zucchinis and eggplants were shallow fried in virgin olive oil (VOO) according to the Mediterranean traditional culinary practice. Zucchinis and eggplants were also blanketed with wheat flour or batter prior to frying. Polyphenols and hydroxy pentacyclic triterpene acids (HPTAs) were determined by GC/MS, while α-tocopherol was determined by high-performance liquid chromatography. Among 12 polyphenols determined, tyrosol predominated in frying oils and zucchini samples, while chlorogenic acid was the major phenolic species in the other vegetable samples. The triterpene acids maslinic, oleanolic and ursolic were determined in frying oils and fried vegetables, while α-tocopherol was present in all samples. Besides water loss and oil absorption, shallow frying resulted in partial loss of all the antioxidants studied in frying oils and enrichment of fried vegetables with olive oil antioxidants, which was in some extent affected by the type of vegetable fried and the culinary practice followed. The overall retention of the antioxidants in oil and food ranged from 32% to 64% for α-tocopherol, 25% to 70% for polyphenols and 35% to 83% for HPTA. It appears that vegetables fried in VOO provide an additional intake of α-tocopherol, terpenic acids and polyphenols as tyrosol and chlorogenic acid.     

COMPARATIVE STUDIES ON PHYSICAL PROPERTIES OF VEGETABLE OILS AND THEIR BLENDS AFTER FRYING

Physical properties of six commonly used oils and three blends consisting of three oils in each blend were studied after three successive frying of 'poories'(fried snack from flattened dough of refined wheat flour). The changes in viscosity, CIE trans-reflectance color and related parameters, UV-Visible spectra and UV-spectra of oil samples in solvent system (chloroform:methanol; 2:1, v/v) were studied. The results showed that viscosity and color of the oils changed to a much higher extent after first frying than subsequent fryings. The hue angle followed a similar trend. Changes in the UV-spectra in the solvent system indicated an increase in the formation of conjugated compounds after successive fryings. Peroxide values (PV) also increased after frying. Principal Component Analysis (PCA) plots of the data indicated that among oils examined groundnut oil and soy oil in combination with other oils were preferred for frying. Use of small amounts of unrefined oils (filtered) such as mustard oil or sesame oil which have a high content of natural antioxidants was beneficial as formation of conjugated compounds and increase in peroxide value was minimized after successive frying using blended oils.     

Physicochemical properties and oxidative stability of frying oils during repeated frying of potato chips

Physicochemical properties and oxidative stability of refined coconut oil (RCO), refined soybean oil (SBO), pure olive oil (POO), and vegetable shortening (VST) during repeated frying of potato chips were determined. Polyunsaturated fatty acids of all the oils significantly decreased after frying. Tocopherols in SBO, POO and VST, and DPPH radical scavenging activities of POO and VST significantly decreased after frying. L* values of the oils significantly decreased, and a* and b* values significantly increased after 80 times repeated frying. Conjugated dienes and p-anisidine value of SBO after 80 times repeated frying were 21.8 mmol/L and 47.7, respectively, the highest among the oils. Levels of total polar compounds of all the oils after 80 times repeated frying were between 8.1 and 9.5%, not exceeding rejection limit after frying. Compositions and contents of alkanals, 2-alkenals, and 2,4-alkadienals in the oils during frying were largely affected by their fatty acid compositions.     

花生油煎炸不同食材过程中3-氯丙醇酯与缩水甘油酯含量变化的研究

对花生油进行油条、薯条、鸡翅、豆腐以及空白煎炸试验,对不同煎炸时间所取油样中3-氯丙醇酯与缩水甘油酯含量进行检测分析,研究花生油煎炸不同食材过程中3-氯丙醇酯与缩水甘油酯含量的变化。结果表明:在间歇煎炸开始后的3 h,油条、薯条、鸡翅、豆腐煎炸油及空白煎炸油中3-氯丙醇酯含量明显升高,由最初的0.84 mg/kg分别增加至9.96、2.17、6.86、4.60、5.41mg/kg;至间歇煎炸15 h,上述对应煎炸油中3-氯丙醇酯含量分别为3.51、1.58、9.88、12.88、3.72mg/kg,缩水甘油酯含量由最初的2.43 mg/kg分别增加至46.47、9.06、40.36、9.00、47.15 mg/kg。随煎炸时间的延长,3-氯丙醇酯增幅最大的是豆腐煎炸油和鸡翅煎炸油,缩水甘油酯增幅最大的是鸡翅煎炸油、油条煎炸油和空白煎炸油。至煎炸15 h,5种煎炸油样的极性组分和酸值均未超出国标限量,但3-氯丙醇酯与缩水甘油酯含量的升高对煎炸食品安全的影响应引起高度关注。