Factors Impacting the Formation of 3-MCPD Esters and Glycidyl Esters During Deep Fat Frying of Chicken Breast Meat

The effect of the frying temperature, frying duration and the addition of NaCl on the formation of 3‐monochloropropane‐1,2‐diol (3‐MCPD) esters and glycidyl esters (GE) in palm olein after deep frying was examined in this study. The eight frying systems were deep‐fat frying (at 160 and 180 °C) of chicken breast meat (CBM) (with 0, 1, 3 and 5% sodium chloride, NaCl) for 100 min/day for five consecutive days. All oil samples collected after each day were analyzed for 3‐MCPD ester, GE, and free fatty acid (FFA) contents, specific extinctions at 232 and 268 nm (K₂₃₂ and K₂₆₈), p‐anisidine value (pA), and fatty acid composition. There was a significant (p < 0.05) decrease in the 3‐MCPD esters and a significant (p < 0.05) decrease in the GE with the increasing of the frying duration. There were significant (p < 0.05) increases in the 3‐MCPD esters formed when the concentration of NaCl increased from 0 to 5%. The addition of NaCl to the CBM during deep frying had no significant effect on the GE generation. The FFA contents, K₂₃₂ and K₂₆₈ and pA showed that all the frying oils were within the safety limit.     

Thermal Decomposition of Partially Hydrogenated Rapeseed Oil During Repeated Frying Traditional and Fast French Fries

The aim of this study was to compare thermal degradation of oil, especially the composition of the polymer in a polar and nonpolar fraction of oil, used for repeated frying of fast and traditional French fries. The French fries were fried using the partially hydrogenated rapeseed oil. Fast French fries were characterized by a half shorter frying time compared to traditional ones. The frying process was done at 170 °C ± 5 °C in 5‐l electric fryers and carried out in 15‐min cycles for 48 hours. The content of thermal decomposition of triacylglycerol (TAG) in both fractions of oil was analyzed by high‐performance size‐exclusion chromatography (HPSEC). In all analyzed samples, thermal decomposition products were found. However, the composition of a polar and nonpolar fraction of oil was not the same. In a nonpolar fraction, only the monomers and hydrolysis products of TAG were observed. In a polar fraction, dimers, trimers, and oligomers of TAG were also found. The shorter time of frying the fast French fries resulted in a lower total and individual polymers content in all steps of analysis compared to the oil used for frying the traditional French fries.     

Water Addition During Oil Extraction Affects on Virgin Olive Oil Ethanol Content,Quality and Composition

Ethanol is the alcoholic precursor of fatty acid ethyl esters (FAEEs) in virgin olive oil (VOO). Because of its miscibility, water addition during oil extraction may affect oil ethanol content and then, the FAEEs synthesis during oil storage. In this work, the effect of water addition on VOO ethanol content and composition is studied. Water addition at two extraction systems (two and three phases) is compared and for vertical centrifuge, water addition at different temperatures is assayed. Ethanol content, quality parameters, and healthy components are determined in the oils. Results indicate three phase system gives oils with a 25% lower ethanol content than two phases. Ethanol reduction because of water addition is more important for three phases system (≈14%). For vertical centrifugation, ethanol is lowered as water dose and temperature increase. In general, water addition for any of the extraction steps analyzed reduces the oil ethanol concentration but other aspects such as fruity intensity and phenol content are also lowered. Practical applications: Virgin olive oil final ethanol content, and then its FAEEs concentration, does not only depend on the health and conservation status of olives, but also on the extraction system used and the amount of water added to the extraction process. The knowledge of the impact on ethanol content of water addition during oil extraction can be useful for olive oil legislators in order to keep the approved limits of FAEEs or to modify them. For oil producers, results can help to reduce the oil ethanol content and then FAEEs synthesis during virgin olive oil storage.     

食品乳化剂柠檬酸甘油单,二酸酯的合成

采用以乙酸为溶剂,柠檬酸和单甘酯进行酯化反应合成了质量指标均符合ＦＡＯ／ＷＨＯ标准的柠檬酸甘油单,二酸酯,确定了合成的最佳工艺条件,并以此为原料配制了两种在常温下呈液态的复合型搞氧剂。试验结果表明,其抗氧化效果超过了国外同类产品,在油脂及含油食品中具有广泛应用价值。     

Effect of Addition of Purified Diglycerol Linoleic Acid Esters on the Crystallization Behavior of Diacylglycerol Oils

Liquid oils containing high‐melting diacylglycerols (DAGs) are more likely to cause precipitation than triacylglycerol‐based oils during long‐term storage, which is not desired for consumer products. Therefore, we attempted to retard the crystallization of high‐melting DAGs by adding emulsifiers, diglycerol esters of fatty acids (DGEs), which were synthesized by esterification of diglycerol and linoleic acid using Novozym 435. The reaction product was isolated by silica gel column chromatography to obtain pure mono‐, di‐, and triesters of diglycerol, and the composition was analyzed by HPLC and ESI‐MS. Further structural analysis of the purified products was performed by ¹H‐ and ¹³C‐NMR. The retardation effect of DGEs with a different esterification degree on the crystallization of DAGs was investigated using solid fat content, differential scanning calorimetry, polarized light microscopy, and X‐ray diffraction. The results reveal that addition of 0.5 % (w/w) DGEs could effectively retard the crystallization of high‐melting DAGs by inhibiting the nucleation process and delaying the crystal growth, but their addition did not alter the crystal forms of DAGs. Moreover, the retardation effect was enhanced as the esterification degree of DGE decreased.     

Effect of Specific Oil Surface Area on the Thermal Stressing of Rapeseed Oil During Heating in an Electric Frying Pan

The effect of specific oil surface (SOS) during pan frying of rapeseed oil on its thermal stability and antioxidant capacity (AC) was evaluated. Rapeseed oils with different oil layer heights (OLH = 0.5, 1.0, 1.5, 2.0, and 2.5 cm) were heated on an electric frying pan coated with Teflon at 180 ± 10 °C until a selected end point of 25 % total polar compounds (TPC) was reached. The changes of chemical parameters of oil samples such as peroxide value, p‐anisidine value, Totox value, free fatty acids, TPC and AC using the 2,2‐diphenyl‐1‐picrylhydrazyl assay were determined. Irrespective of the applied methods, the highest changes in oil with OLH = 0.5 cm were observed. Heating in low OLH also led to the fastest time of TPC formation in rapeseed oil; the 0.5‐cm layer reached 25 % TPC in a relatively short time (71.5 min) compared to the highest OLH = 2.5 cm (t = 315.1 min). The SOS and the rate of change in the heated oils decreased with increasing OLH. Crucial effects of SOS on physicochemical oil changes were observed. The present study demonstrated the protective effect of increasing the OLH on the quality of the heated rapeseed oils.     

油脂化学工业中酶与微生物开发利用的新进展

评述了油脂化学工业中酶、微生物开发应用的新进展。介绍了脂肪酶的分解，脂肪酸、脂肪醇的微生物转化和利用微生物生产不饱和脂肪酸及油脂等过程。指出生物工艺学的发展前景。     

Comments on a Method for Estimating Cloud Point and Cold Filter Plugging Point of Microalgal Oil Fatty Acid Methyl Esters

Cloud points (CPs) of five vegetable oil fatty acid methyl esters (FAME) and three biodiesel mixtures estimated by a thermodynamic equation were compared to measured CPs. The results indicate that estimated CP of peanut oil FAME are similar to measured CP and for three biodiesel mixtures a minimum total saturated FAME (SFAME) concentration is required for measured CPs to be closer to estimated CPs. These comparisons provide the basis for comments on using this method for estimating CPs of 22 test data of microalgae FAME. Cold filter plugging points (CFPPs) calculated by equation CFPP = 1.0191 × CP ? 2.9 with CPs verified from the thermodynamic equation was found to be identical to CFPPs reported in literature for 22 test data of microalgae FAME. Therefore these CPs were inserted in equation CFPP = CP ?4.5 for another set of CFPPs. Plots of CFPPs versus percent SFAME of the 22 test data of microalgae FAME (>12 %) for these two equations indicates that CFPP is controlled by 85 % of SFAME. Calculated CFPPs of vegetable oil FAME and biodiesel mixtures using both equations for estimated and measured CPs is discussed. Low concentrations of long chain saturated FAME impacting the estimation of CPs of vegetable oil FAME is used as a rationale to discuss the role of unidentified other species (OS) in estimation of CPs of microalgae FAME.     

香榧种子含油量及脂肪酸组成对比研究

为探究不同品种香榧种子含油量及组成的差异,对同一产地不同品种的11种香榧（旋纹榧、茄榧、大圆榧、米榧、象牙榧、芝麻榧、普通榧、木榧、小圆榧、炭盆榧和寸金榧）种子的含油量以及种子油脂肪酸组成进行了对比研究,结果表明：不同品种的香榧种子含油量及种子油脂肪酸类型都表现出明显差异。11种不同香榧种子含油量约2%~14%,普通榧最高（13.4%）,炭盆榧最低（2.2%）;脂肪酸种类最少8个,最多13个（寸金榧和木榧）。香榧种子油以不饱和脂肪酸为主,其总量超过66%。普通榧不饱和脂肪酸总量达到85.87%,其中主要成分油酸、亚油酸总量超过72%。所有品种的香榧种子油都含有超过6.90%的特殊脂肪酸金松酸,而且以普通榧中含量最高,达到10.41%。     

The Characteristic Relationship Between Oil Uptake and Moisture Content during the High Temperature Immersion Frying of Thin Potato Crisps

Thin potato crisps (2mm) were fried at 170℃, 180℃ and 190℃ for various times from 10s to 180s inclusive. It was found that definite oil uptake, moisture loss trends exist during the frying process. No significant difference in the oil uptake or moisture loss rates between flat-cut and ridge-cut crisps exists. Also found in this study was that an increased oil temperature promoted higher moisture loss rates. In turn, the higher moisture loss rates contributed to a higher oil uptake rate. It was found, based on the volumetric plots of oil content vs. water content, that the oil uptake rate was proportional to the moisture loss rate. As a result, it has been shown that there is a possibility of having a characteristic curve of oil uptake against moisture content.     

高温油炸薄薯片过程中油的吸收和水分流失间的特性关系

Thin potato crisps (2mm) were fried at 170℃, 180℃ and 190℃ for various times from 10s to 180s inclusive. It was found that definite oil uptake, moisture loss trends exist during the frying process. No significant difference in the oil uptake or moisture loss rates between flat-cut and ridge-cut crisps exists. Also found in this study was that an increased oil temperature promoted higher moisture loss rates. In turn, the higher moisture loss rates contributed to a higher oil uptake rate. It was found, based on the volumetric plots of oil content vs. water content, that the oil uptake rate was proportional to the moisture loss rate. As a result, it has been shown that there is a possibility of having a characteristic curve of oil uptake against moisture content.     

Efficiency of Gold Nano Particles on the Autoxidized Soybean Oil Polymer: Fractionation and Structural Analysis

Polyunsaturated plant oils have gained great interest as monomers to produce biodegradable polymers obtained from renewable resources due to the limited existing sources of petroleum oil and environmental issues. Soybean oil was autoxidized by exposure to atomospheric oxygen at room temperature with or without the presence of gold nanoparticles (Au NPs) 5–41 days. When the autoxidation process was catalyzed with Au NPs, the molecular weight of the oxidized oil was increased in 5 days. In contrast to this, without Au NPs, the oxidized oil was still a fluidized liquid. Autoxidized soybean oil polymer in toluene solution with gold NP showed a surface plasmon resonance at λ_max = 540 nm in a UV–VIS spectrometer and a fluorescence emission spectrum at λ_max = 450 nm, when it was irradiated at λ_max = 390 nm. The higher molecular weight of the polymeric oils was successively fractionated by the extraction from the solvent‐non‐solvent mixture CHCl₃/petroleum ether with the volume ratio of 5:15. Three polymeric oils fractions with different molecular weight (ca 1000, 4000, and 40,000 g/mol) were obtained. GC–MS analysis, ¹H‐NMR and GPC techniques were used in the structural analysis of the fractionated polymeric oils.     

High Content of Dicranin in <Emphasis Type="Italic">Anisothecium spirale</Emphasis> (Mitt.) Broth., a Moss from Eastern Himalayas and Its Chemotaxonomic Significance

Chemical investigation of Anisothecium spirale (Mitt.) Broth. (Family Dicranaceae), an epiphytic moss from the Darjeeling district hill region of the Eastern Himalayas was performed for the first time. Analysis of neutral lipid and phospholipid classes as well as their respective fatty acids revealed the presence of a significantly high content of octadeca-6-yn-9,12,15-trienoic acid, an acetylenic fatty acid commonly known as dicranin. Dicranin and a less abundant acetylenic fatty acid were detected in neutral lipids. The unique nature of the fatty acid signature supports the view of considering dicranin as chemotaxonomic marker for Dicranaceae members.     

精制油氮含量对加氢裂化及其产品影响的考察

考察了高压一段串联加氢裂化工艺不同类型加氢裂化催化剂的耐氮性能、高氮条件下的催化剂活性稳定性、经历高氮运转后催化剂反应性能的恢复情况和相同裂化深度时精制油氮含量对产品分布和产品性质的影响,以及中压条件下精制油氮含量对加氢裂化转化率的影响。     

释香过程中茉莉净油组成与含量变化规律研究

有机溶剂浸提制备茉莉净油,经GC、GC/MS分析,内标法定量,鉴定了27个主要组分.组分中由苯甲醇、苯甲酸、顺-3-己烯醇为基本结构单元酯类化合物种类较多且含量高;与头香相比,净油中还含有脂肪酸及其甲酯、苯甲酸苯甲酯等5个高沸点组分;释香过程中,净油、酯类、Ⅱ区组分总量和主要香气组分含量呈低-高-低变化趋势,而醇类、Ⅰ、Ⅲ区组分含量变化与之相反;6种组分与净油香气浓度变化呈显著正相关;用香气品质指数AI(∑Ⅱ/∑Ⅰ Ⅲ)评价了净油品质,具正常茉莉花香特征的香精油AI值以大于2.5为宜.提出了茉莉花酯类香气组分形成的可能途径.     

Dynamic Accumulation of Volatile Compounds Between Olive Pulps and Stones and Its Relation with the Fatty Acids Content During the Oil Extraction Process of Ouslati and Chemlali Olive Fruits

The characterization of both volatiles and fatty acids of Tunisian olive varieties (Ouslati and Chemlali) is achieved in order to understand their correlation with the aroma accumulation via the lipoxygenase (LOX) pathway. The main identified volatiles in both crushed pulps and crushed stones are hexanal, E‐(2)‐hexenal, (Z)‐3‐hexen‐1‐ol, 1‐hexanol, and hexyl acetate. With regard to their fatty acid composition, results show that both de‐stoned (DOO) and conventional (COO) olive oils contain mainly unsaturated fatty acids. The results also show that oleic acid (C18:1) is the main fatty acid in both DOO and COO. Meanwhile, linoleic acid (C18:2) is present in a relatively higher percentage (5.2% and 19.8%, respectively, for Ouslati and Chemlali DOI) than linolenic fatty acid (C18:3) (<2%). The analysis of volatiles shows that more than 80% of total LOX‐compounds from both crushed pulps and crushed stones have linolenic acid as synthesis precursor despite its lower level (2%). Moreover, the contribution of olive parts in generating aroma is much higher in crushed pulps (more than 80%) than in crushed stones, which explains the fact that DOO, extracted from crushed pulps, contains the dominant amount of volatiles. Therefore, the obtained results promote both the consumption and the marketing of DOO. Practical Applications: The aroma and the organoleptic properties of olive oil are strictly correlated with both the olives quality and the extraction techniques used. Many technologies are developed to extract olive oil with highest quality. De‐stoned olive oil extraction process is one of these technical procedures. In the present work, the characterization of volatiles in pulp and stone separately provides important information about the contribution of olive constitutive parts on the accumulation of olive oil aroma during the oil extraction process.     

表面活性剂体系改善高含蜡稠油破乳脱水效果

筛选出效果较好的几种破乳剂,与自主研制的破乳剂DH进行复配,得到DH-fp破乳剂体系,无论是室内还是现场应用,均取得良好的破乳脱水效果,达到外输油含水率低于O．5％和脱出污水含油率低于50mg·L-1。的标准。采用稳定性分析法与传统瓶试法对破乳效果进行评价,新方法与旧方法的结果一致,但可以较大地提高工作效率。     

Effect of the Presence and Absence of Potatoes under Repeated Frying Conditions on the Composition of Palm Oil

The effect of repeated deep frying of potatoes versus repeated heating/quenching on the chemical profile of palm oil was investigated. The novelty of the work is that the frying and heating/quenching experiments were conducted under similar time-temperature profiles. The effects of the frying load (potato-to-oil ratio: 1/7 and 1/35 kg_potatoes/l_oil) and of the time-temperature profile were examined. Whole palm oil and its polar fraction were analyzed using high pressure size exclusion chromatography. Both repeated frying and repeated heating/quenching generated polar and polymerization products in palm oil. Interestingly, no hydrolysis or other decomposition products were generated under any of the examined conditions. The presence of potatoes during frying in palm oil increased the concentration of polymerization products and polar compounds compared to oils without potatoes significantly. The effects of frying load on oil quality depended on frying time. No significant effect of frying load was observed up to frying times of 13 h (or 10 frying batches). However, frying oil quality was affected by frying load once frying times exceeded 24 h (or 20 batches).