Lipochromes,vitamins, aromas and other components of virgin olive oil are affected by processing technology

A stone mill-integral decanter (SD) olive processing line was compared with a traditional stone mill-press (SP) line, a discontinuous method, that, if properly used, yields high-quality virgin olive oils. With “difficult olives” (not easy to process), the SD line yielded oils characterised by: (1) higher contents of pleasant volatiles, tocopherols, β-carotene, xanthophylls, chlorophylls, pheophytins and waxes; (2) higher values of the 1,2-diglycerides/1,3-diglycerides ratio, integral colour index and chroma; (3) lower contents of phenols, secoiridoids, unpleasant volatiles, aliphatic alcohols, triterpene alcohols and sterols; and (4) lower values of turbidity, brightness and oxidative stability. With “non-difficult olives” (easy to process), whose paste needed to be fluidised with lukewarm water, the SD line yielded oils showing higher contents of pleasant volatiles and tocopherols, lower contents of unpleasant volatiles and comparable contents of phenols and lipochromes. The content of organophosphorus pesticide residues did not depend on the processing method.     

Comparative evaluation of the olive oil given by a new processing system

To evaluate the level of quality of the olive oil given by a new processing system we compared it with the percolation oil, which is known to be of high quality. The new product was characterized by the following: (i) higher contents of tocopherols, tyrosol- and hydroxytyrosol-aglycones, volatile aromatic substances, sterols, triterpene alcohols and lipochromes, and higher values of 1,2-diglycerides/1,3-diglycerides and campesterol/stigmasterol ratios, colour indices and turbidity; (ii) lower contents of waxes and triterpene dialcohols, and lower values for spectrophotometric indices, carbonyl index, Wolff's ratio (K₂₃₂/K₂₇₀), acidity, and peroxide number; (iii) similar contents of phenols, o- diphenols, free tyrosol, free hydroxytyrosol, triglycerides, stigmastadienes, and aliphatic alcohols, similar sensory score, and similar value of resistance to autoxidation, alcohol index, overall quality indices, and fatty acid composition.     

Evaluating two kinds of centrifuged virgin oils arising from continuous olive processing

Oils extracted from olive pastes by the direct centrifugation mode were compared with the homologous oils produced by the indirect centrifugation (after percolation) mode. The former were characterised by: (i) higher contents of total phenols, o‐diphenols, hydroxytyrosol, hydroxytyrosol‐aglycons, total volatiles, trans‐2‐hexanal and other pleasant volatiles, total tocopherols, total sterols and waxes; (ii) lower contents of triterpene dialcohols, aliphatic and triterpene alcohols, chlorophylls and pheophytins; (iii) lower values of integral colour index; (iv) higher values of turbidity, campesterol/stigmasterol ratio, 1,2‐diglycerides/1,3‐diglycerides ratio, oxidative stability and overall quality indices; and (v) higher sensory score. Stigmastadienes and trans‐isomer C₁₈ fatty acids were always not detected. The average oil outputs of the two centrifugation extraction procedures were comparable, as confirmed by similar overall oil amounts found in the by‐products. © 2000 Society of Chemical Industry     

GC-O结合OAV鉴定陇南初榨橄榄油关键香气成分

选取甘肃陇南代表性品种莱星和鄂植8号初榨橄榄油及消费口碑良好的特级混合初榨橄榄油为研究对象,通过气相色谱-质谱（gas chromatography-mass spectrometry,GC-MS）检测比较3 种初榨橄榄油的挥发性物质组成,同时采用气相色谱-嗅闻（gas chromatography-olfactometry,GC-O）技术筛选其香气活性物质,最后结合香气活性值（odor activity value,OAV）分析各呈香组成对橄榄油香气轮廓呈现的贡献性,从而鉴定出3 种橄榄油各自的关键香气成分。结果表明：采用GC-MS在莱星、特级混合及鄂植8号初榨橄榄油中各检测出35、30 种及25 种挥发性成分,其中己醇、3-己烯-1-醇、(E)-2-己烯-1-醇和(E)-2-己烯醛的含量丰富。采用GC-O在3 种初榨橄榄油中各筛选出13、15 种和12 种香气活性成分,包含具有青草特征的C6化合物、呈现油脂香气的庚醛和(E,E)-2,4-癸二烯醛以及表现其他气味信息的香气物质。OAV分析发现3 个样品各有12、13 种及11 种关键香气成分（OAV≥1）,以1-辛烯-3-醇、芳樟醇、(E)-2-己烯醛和(E,E)-2,4-癸二烯醛为代表的OAV较高,对初榨橄榄油呈香品质具有重要作用。本研究筛选出3 种初榨橄榄油的关键香气成分,结果可为提升初榨橄榄油风味品质提供理论基础。     

成熟度指数对不同品种橄榄油脂肪酸、 酚类化合物及风味属性的影响

以甘肃省陇南市油橄榄研究所种质资源基因库的‘城固32号’和‘莱星’油橄榄果为原料提取橄榄油,运用GC-MS、HPLC和E-Nose对不同品种与不同成熟度指数的橄榄油脂肪酸、酚类化合物及风味属性进行检测分析,以探究成熟度指数与不同品种橄榄油品质的关系。结果表明：随着成熟度指数的增大,‘城固32号’橄榄油中的硬脂酸、油酸、亚麻酸、饱和脂肪酸（SFA）含量及单不饱和脂肪酸/多不饱和脂肪酸（MUFA/PUFA）和油酸/亚油酸值呈下降趋势,亚油酸和不饱和脂肪酸（UFA）含量呈上升趋势,‘莱星’橄榄油中油酸和UFA含量及MUFA/PUFA和油酸/亚油酸值呈上升趋势,而亚油酸、亚麻酸和SFA含量呈下降趋势;油酸/亚油酸和MUFA/PUFA值在2个品种间存在差异,可作为鉴别‘城固32号’和‘莱星’橄榄油的依据;2个品种橄榄油中酪醇和总酚含量总体呈下降趋势,香草酸和木犀草素含量总体呈上升趋势,而羟基酪醇含量在‘城固32号’中总体逐渐减少,在‘莱星’中总体逐渐增加,木犀草苷含量在2个品种中保持稳定;风味物质的E-Nose信号响应值在2个品种中均显著减小。利用橄榄油中脂肪酸和酚类化合物的组成与含量以及风味属性的信号响应值差异结合主成分（PCA）分析可有效鉴别和区分不同成熟度指数的‘城固32号’和‘莱星’橄榄油。     

Composition and Quality of Pressed Virgin Olive Oils Extracted with a New Enzyme Processing Aid

ABSTRACT Virgin olive oils extracted with an enzyme complex were characterized with respect to the control oils by: (1) higher contents of major individual phenols (free + aglycons), o‐diphenols, total phenols, tocopherols, pleasant volatiles (including those from lipoxygenase pathway), green (chlorophylls and pheophytins) and yellow (carotenoids) lipochromes, higher aliphatic and triterpene alcohols, phytol, citrostadienol, triterpene dialcohols, and steroids; (2) lower contents of unpleasant volatiles and waxes; (3) highervalues of chroma, integral color index, and 1,2‐diglycerides/1,3‐diglycerides ratio; (4) higher sensory, bitter, spicy, and green fruit scorings; and (5) lower values of lightness and turbidity. The organophosphorus pesticide residues were usually not detected in the oils produced with or without enzyme.     

PRODUCTION OF LOW-FAT FRANKFURTERS WITH VEGETABLE OILS FOLLOWING THE DIETARY GUIDELINES FOR FATTY ACIDS

Low-fat frankfurters (10% fat) were produced with vegetable oils following the dietary guidelines for fatty acids as suggested in the currently recommended diet (CRD) by the American Heart Association, the Grundy diet (GD) and the Mediterranean diet (MD). MD-frankfurters, produced with olive oil (31.82%) and soybean oil (17.51%), had the highest (P<0.05) ratio of monousaturated fatty acids (MUFA)/saturated fatty acids (SFA) minus stearic. CRD-frankfurters, produced mainly with cottonseed oil (40.70%) and soybean oil (6.90%), had the highest (P<0.05) content of polyunsaturated fatty acids (PUFA). GD-frankfurters, produced with cottonseed oil (34.04%) and olive oil (15.19%), had the highest (P<0.05) ratio of (C18:2 n-6)/(C18:3 n-3). Compared to high-fat frankfurters (27% all animal fat), low-fat frankfurters had lower (P<0.05) stearic acid and trans ω-9 oleic acid, higher (P<0.05) content of total PUFA, higher (P<0.05) ratio of (C18:2+C 18:3)/SFA minus stearic acid, and lower cholesterol content (52.60%-59.11%), were darker, redder and more yellow, firmer and less juicy, but had similar overall acceptabily.     

Microwave Energy Effects on Quality of Some Seed Oils

Effects of microwave heating were investigated on chemical properties of seed oils in relation to tocopherol contents. For assessing quality of oils (linseed, soybean, corn, olive, and palm) during microwave treatments, peroxide, thiobarbituric acid, carbonyl and anisidine values were determined. As the amount of polyunsaturated fatty acids in oils increased the index for the chemical properties increased. After 8-10 min heating the amount of tocopherols decreased substantially in linseed, olive and palm oils, whereas that in corn and soybean oils was still ca. 90%. Thus, the reduction in tocopherols in oils is not necessarily in agreement with chemical properties of the oils.     

FTIR技术结合区间偏最小二乘法快速测定油脂中反式脂肪酸

研究了傅里叶红外光谱技术结合区间偏最小二乘法(iPLS)快速分析食用油中低含量(0.1%~5%)反式脂肪酸的分析方法。通过系统地比较衰减全反射红外光谱法(ATR-FTIF)及衰减透射红外光谱法(TR-FTIR)光谱的模型效果,优化建模区间。研究结果表明,ATR-FTIR、TR-FTIR-PLS回归模型均能有效测定油脂中低浓度反式脂肪酸的含量,但TR-FTIR法灵敏度优于ATR-FTIR法。iPLS区间选择结果显示,以1 000~940 cm~(-1)波段透射光谱建模,相关系数R~2为0.998 8,标准集的RMSEC 0.016 6,验证集RMSEP为0.008 75,预测相对标准偏差2.92%,预测值与实际值高度相关,Y_(预测)=1.00X_(实际)-0.003 44,R~2=0.998 7。12组外部验证试验相对标准偏差为4.80%,说明预测精确度较高、模型稳定性好,有潜力替代传统气相色谱法用于油脂中低含量反式脂肪酸快速定量测定。     

DISCRIMINATION OF SOME TUNISIAN OLIVE OIL VARIETIES ACCORDING TO THEIR OXIDATIVE STABILITY, VOLATILES COMPOUNDS AND CHEMOMETRIC ANALYSIS

Oxidation stability is a key property of olive oil quality and is affected by different antioxidant compounds whose levels may be influenced by several factors such as cultivar and place of production. Polyphenols, carotenoids, chlorophylls, fatty acids levels and some volatiles were correlated to oxidative stability in olive oils in five samples studied. Total polyphenols and saturated to polyunsaturated fatty acids (and/or oleic to linoleic acid ratio) ratio were shown to be the major parameters in oil antioxidant stability, according to analysis of variance and principal component analysis. The hexanal/E-2-hexenal ratio is a very important indicator of the freshness of the oils and can estimate their oxidation degree.

PRACTICAL APPLICATIONS

The present study gives information about the importance and the variability of some Tunisian olive oil varieties in both their quality (high oxidative stability) and good organoleptic properties which could be appreciated by consumers.     

Effect of Fat Level and Partial Replacement of Pork Backfat with Olive Oil on the Lipid Oxidation and Volatile Compounds of Greek Dry Fermented Sausages

ABSTRACT: High- and reduced-fat Greek fermented sausages were produced with 30% and 20% total fat in the initial formulation. The same products were manufactured with a partial replacement of pork backfat with 20% olive oil. The influence of the modification of the lipid fraction on the oxidation process was evaluated after 2 mo of storage. The reduction of fat increased thiobarbituric acid (TBA) values, total aldehydes, and typical lipid oxidation compounds (hexanal, 2-hexenal, 2-octenal). A significant decrease in oxidation was detected in batches containing olive oil, particularly in the sausages with the highest olive oil content. This addition decreased, in both fat level products, TBA values and hexanal, 2-hexenal, 2,4-hexadienal, benceneacetaldehyde, tt,2,4-nonadienal, and pentadecanal. The addition of olive oil significantly increased monounsaturated fatty acids content.     

Influence of fatty acids compositions and manufacturing type on the formation of 4-hydroxy-2-alkenals in food lipids

Correlations between 4-hydroxy-2-hexenal (HHE) or 4-hydroxy-2-nonenal (HNE) and fatty acids were statistically investigated in 73 kinds of commercially available food sources of n-3 or n-6 polyunsaturated fatty acids (PUFA). The analysis revealed that the level of HNE was obviously correlated with the contents of PUFA (r=0.462), n-6 PUFA (r=0.512), and saturated fatty acids (r=0.535). Significant correlation was also observed between HHE and HNE (r=0.486) although whose source fatty acids were different. Regarding the sesame oils and perilla oils currently available on the Korean markets, no appreciable difference in the levels of HHE or HNE was found depending on their manufacturing types.     

Lipolytic activity of Williopsis californica and Saccharomyces cerevisiae in extra virgin olive oil

Inoculation trials performed with three strains of yeasts, isolated from extra virgin olive oil, Williopsis californica 1,639, Saccharomyces cerevisiae 1,525 and Candida boidinii 1,638, demonstrated that some yeast can lower the quality of the oil during storage. Laboratory tests highlighted a substantial increase in the total diglycerides and free fatty acids in the samples of oil inoculated with the lipase-producing strains of yeasts, W. californica 1,639 and S. cerevisiae 1,525, while in the samples of oil inoculated with the lipase-negative strain C. boidinii 1,638 no differences were found in respect to the uninoculated control. The acidity of the extra virgin olive oil, inoculated with the lipase-producing strains W. californica 1,639 and S. cerevisiae 1,525, during 2 weeks of incubation at 30 degrees C increased respectively from 0.62% to 1.50 and 1.62%, exceeding the limit of 0.8% established by current regulations for this commercial category of olive oil, while in the oil inoculated with the lipase-negative strain and in the uninoculated control, the acidity remained constant throughout. Furthermore, the two strains of lipase-producing yeasts also increased the concentration of the 1.3-diglyceride isomer in the oil lowering the values of the total 1.2-diglycerides/total 1.3-diglycerides ratio considered to be an important index of quality for an extra virgin olive oil. The lipolytic activity of lipase-producing strains W. californica 1,639 and S. cerevisiae 1,525 showed an optimum pH of 6 and 7.5 and an optimum temperature of 20 degrees C and 30 degrees C respectively. Nevertheless, the lipolytic activity was negatively influenced by glucose and polyphenols when the concentration was higher than 0.25% and 0.4% (wt/vol) respectively.     

初榨橄榄油挥发性风味成分的鉴定

采用顶空固相微萃取-气质联用(HS-SPME-GC/MS)分离鉴定了陇南市武都初榨橄榄油和西班牙特级初榨橄榄油中的挥发性风味成分。结果表明,在7个不同品种油橄榄的国产初榨橄榄油中共鉴定出86种化合物,主要是C6的醛和醇,以及它们相应的酯,还有一些烯烃和萜烯类化合物。其中(E)-2-己烯醛相对质量分数为7.14%~46.22%;在6个西班牙特级初榨橄榄油中共鉴定出101种化合物,其中(E)-2-己烯醛质量分数(1.76%~5.25%)低于国产初榨橄榄油,而(Z)-乙酸-3己烯酯(7.53%~13.76%)和(E)-2-十二碳烯(5.47%~34.75%)相对质量分数较高。试验结果还表明,初榨橄榄油挥发性风味成分很大程度上取决于油橄榄品种和产地。     

The glyceridic and nonglyceridic constituents of virgin olive oil after use of a novel method of enzyme extraction

Summary The composition of three virgin olive oil varieties (Caroleo, Coratina and Leccino) was investigated after extraction with a new enzyme processing aid called Bioliva. Comparisons with reference oils extracted without using the biological preparation were made. The oils extracted by enzymes showed the following features: (i) higher contents of total phenols, o‐diphenols, major free and hydrolysable phenols, tocopherols, chlorophylls, pheophytins (Mg‐free chlorophyll derivatives), β‐carotene, major xanthophylls (lutein, violaxanthin and neoxanthin), agreeable volatiles, long‐chain aliphatic alcohols and superior triterpene alcohols; (ii) lower contents of disagreeable volatiles; (iii) higher sensory scoring and resistance to autoxidation; (iv) higher values of Naudet's integral colour index, carotenoid colour index, chroma and 1,2‐diglycerides/1,3‐diglycerides ratio and (v) lower values of lightness. These findings suggested that the oil's analytical pattern was meaningfully improved following this novel enzyme treatment.     

Some chemical and microbiological properties of ghee produced in Eastern Anatolia

Some properties of 30 ghee samples produced in Eastern Anatolia in Turkey were evaluated. Lipolytic bacteria and yeast–mould counts ranged from undetectable to 9.9  ×  10⁵ and 6.9  ×  10⁵ cfu/g, respectively. Most of the samples showed higher free fatty acids (FFA) and peroxide values (PV) than the limits mentioned in International Dairy Federation standards. Storage at 5°C for 30 days was not sufficient to stop the lipolytic and yeast–mould growth and lipid oxidation of the samples. Ghee samples with considerably higher trans -C18 : 1 and trans -C18 : 2 fatty acids contents were considered to be adulterated with hydrogenated oils. It is recommended that specific attention should be given to technology transfer and the education of traditional dairy product manufacturers.     

气相色谱法测定植物油中反式脂肪酸不确定度的评定

参照国家标准GB/T 22110—2008《食品中反式脂肪酸的测定气相色谱法》测定植物油中反式脂肪酸,对测定结果的不确定度进行了评定。结果表明本实验室能准确测定植物油中反式脂肪酸,扩展相对不确定度结果为4.2%(K=2),在整个不确定度中,气相色谱测量结果重复性占总不确定度的比例最大,为今后开展该类项目检测,对其结果准确性的控制提供了技术参考。     

Profiles of volatile compounds from some monovarietal Tunisian virgin olive oils. Comparison with French PDO

The volatile profiles of seven Tunisian and four French virgin olive oils were established by solid phase micro-extraction (SPME) and gas chromatography (GC), using flame ionisation and mass spectrometer detectors. Eighty-six compounds were identified and characterized, representing 97.4–99.9% of the total GC area. (E)-2-hexenal, the main compound extracted by SPME, characterized the olive oil headspace for approximately 90% of the oils examined. Significant differences in the proportions of volatile constituents from oils of different varieties were detected. The results demonstrated that the accumulation of the different metabolites in the oils obtained from the various cultivars was strictly connected with the varietal parameters on the basis of the enzyme differences genetically determined. This feature made possible the differentiation of the examined cultivars on the basis of the percent of each metabolite.     

Effect of cooking on the chemical composition of low-salt, low-fat Wakame/olive oil added beef patties with special reference to fatty acid content

Changes in chemical composition, with special reference to fatty acids, as affected by cooking, were studied in low-salt (0.5%)/low-fat patties (10%) with added Wakame (3%) and partial or total replacement of pork backfat with olive oil-in-water emulsion. The addition of Wakame and olive oil-in-water emulsion improved (P < 0.05) the binding properties and the cooking retention values of moisture, fat, fatty acids and ash, which were close to 100%. Partial and total replacement of animal fat with olive oil-in-water emulsion reduced (P < 0.05) saturated fatty acids (SFAs), while total replacement also reduced (P < 0.05) polyunsaturated fatty acid (PUFAs) contents. The fatty acid concentration in cooked patties was affected by product formulation. Unlike the case of all animal fat patties, when olive oil was added the cooking process increased (P < 0.05) SFAs, monounsaturated fatty acids (MUFAs) and PUFA n-3 (linolenic acid) and n-6 (linoleic acid) contents. Cooked formulated patties with seaweed and partial or total replacement of pork backfat by oil-in-water emulsion and with seaweed added were less calorie-dense and had lower SFAs levels, while samples with olive oil had higher MUFAs levels.     

Performance of virgin olive oil and vegetable shortening during domestic deep-frying and pan-frying of potatoes

The performance of virgin olive oil and a commercial vegetable shortening was investigated during 10 successive pan-fryings of potatoes at 180 °C for a total period of 60 min and during 10 successive deep-fryings at 170 °C for a total period of 120 min. These are typical conditions of Greek domestic cooking. For both the oils tested the effect of pan-frying on K232, K268, K316, α-tocopherol, total polar artefacts, Rancimat induction times, octanoic acid formation and linoleic acid decomposition was worse than the effect of deep-frying on the same variables. The same was true for visible spectrum and total phenols in virgin olive oil. No systematic variations of oleic acid, refractive index and trans -isomers of fatty acids were detected. None of the oils reached the limit of 25–27% total polar artefacts. Both oils performed similarly during pan-frying, while virgin olive oil performed better during deep-frying. A very strong correlation between octanoic acid formation and total polar artefacts in the whole data set was observed.