3个引进油橄榄品种初榨油多酚类化合物含量及抗氧化活性研究

以3个引进油橄榄品种初榨油为材料,测定总多酚含量和各单体酚含量并评价其抗氧化活性,同时采用SPSS应用软件分析总多酚含量、各单体酚含量与体外抗氧化活性的相关性。结果表明:3个品种总多酚含量分别为21.26、23.31、26.04μg/g,品种间无显著差异,而单体酚含量均较少;3个品种中佛奥对DPPH自由基的清除能力最强,而对羟基自由基的清除能力和Fe2+螯合能力则是豆果最强;羟基酪醇含量与DPPH自由基清除能力、羟基自由基清除能力和Fe2+螯合能力极显著负相关或显著正相关,相关系数分别为-0.956、0.713、0.721;对羟基苯甲酸含量与Fe2+螯合能力显著正相关;槲皮素含量与DPPH自由基清除能力显著负相关,与Fe2+螯合能力显著正相关;而总多酚含量、咖啡酸和表儿茶素含量与体外抗氧化能力的的相关程度较低,因此羟基酪醇、对羟基苯甲酸和槲皮素是主要的抗氧化成分。     

初榨橄榄油风味化合物研究进展

阐述了初榨橄榄油风味的主要来源途径即脂氧合酶途径,对影响初榨橄榄油风味特征的若干因素如品种和地理环境,油橄榄果实成熟度,加工工艺,储藏条件等因素进行了讨论和分析.介绍了初榨橄榄油中挥发性化合物的分析检测方法,并且展望了橄榄油风味化合物研究的应用和发展前景.     

初榨橄榄油中的微生物群及其对橄榄油品质的影响

初榨橄榄油生产环境相对开放,榨取橄榄油的原料、环境及设备中的微生物群都可能进入初榨橄榄油,对油脂品质产生影响。为全面认识初榨橄榄油中微生物群以及从微生物层面控制初榨橄榄油品质,从食品微生物学研究的视角,综述了初榨橄榄油中酵母菌、细菌和霉菌等主要微生物群,分析了油橄榄枝叶、果实和初榨橄榄油中的微生物群对油脂品质的影响,介绍了采后储存的油橄榄果实及储存期的初榨橄榄油品质与微生物群之间的关系,探讨了对有害微生物群影响初榨橄榄油品质的防控措施。研究认为酵母菌对初榨橄榄油储存期间的品质起主要的影响作用。通过避免采摘和储存过程中油橄榄果实的损伤,保证加工过程中清洗用水和设备的洁净,控制储存环境温度、光照和氧含量等措施,可以有效防控有害微生物对橄榄油品质的负面影响。     

Antioxidant activity of virgin olive oil phenolic compounds in a micellar system†

The antioxidant activity of two virgin olive oils, obtained from the same olive (Olea europaea sativa) batch but processed with different hammer crushing conditions, was evaluated by measuring their protective action towards linoleic acid peroxidation in a micellar system. The antioxidant efficiency (AE) of the oil phenolic fraction was higher when the olives were processed with a higher hammer crusher rotation rate. HPLC analysis demonstrated that one of the main derivatives of oleuropein, indicated as 3,4-DHPEA-EDA (the dialdehydic form of elenolic acid linked with 3,4-dihydroxyphenylethanol), is present only in the oil with higher AE. 3,4-DHPEA-EDA showed the greatest antioxidant ability among virgin olive oil phenols. Its greater efficiency in the micellar system in comparison with 3,4-dihydroxyphenylethanol (3,4-DHPEA) is related to its greater lipophilicity. It is suggested that the behaviour in the water–micellar environment is representative of that in a real system such as tomato-based sauce with added virgin olive oil. © 1999 Society of Chemical Industry     

Contribution of polyphenols to the oxidative stability of virgin olive oil

Stability, polyphenol, orthodiphenol, tocopherol, oleic/linoleic ratio, chlorophyll, carotenoid, peroxide and acidity values, K₂₃₂, K₂₇₀ and overall sensory score of virgin olive oils from Hojiblanca and Picual cultivars were determined during two consecutive seasons. Changes due to cultivar and season were evaluated, correlations between the changes were studied and their contribution to stability was investigated by multiple regression techniques. Removal of polyphenols from the original samples without altering other antioxidant components has permitted estimating, for the first time, the contribution of these compounds to virgin olive oil. Approximately 50% of the stability is contributed by polyphenols. © 2001 Society of Chemical Industry     

Contribution of olive seed to the phenolic profile and related quality parameters of virgin olive oil

BACKGROUND: Conflicting results have been reported about the effect of fruit de‐stoning on the virgin olive oil (VOO) phenolic profile. The aim of the present study was to determine whether olive seed plays any role in the synthesis of this oil phenolic fraction. RESULTS: Increases of around 25% of total phenolic compounds were observed in oils obtained from de‐stoned olive fruits in three main Spanish cultivars. To investigate the involvement of olive seed in determining the phenolic profile of VOO, whole intact olive fruits were added with up to 400% olive stones. Excellent regression coefficients were found in general for the decrease of total phenolic compounds and, particularly, of o‐diphenolics in the resulting oils. On the other hand, it was found that olive seed contains a high level of peroxidase (POX) activity (72.4 U g^?1 FW), accounting for more than 98% of total POX activity in the whole fruit. This activity is able to modify VOO phenolics in vitro, similar to the effect of adding stones during VOO extraction. CONCLUSION: Olive seed plays an important role in determining VOO phenolic profile during the process to obtain an oil that seems to be associated with a high level of POX activity. Copyright © 2007 Society of Chemical Industry     

Heat-oxidation stability of palm oil blended with extra virgin olive oil

Rancimat induction time of palm oil (PO), several extra virgin olive oils (EV) and their binary blends have been determined at three different temperatures (120, 130 and 140°C). Analytical composition and oxidation stability of PO/EV blends were found to be a linear combination of the oil partners. Induction time of pure PO was always higher than those of EV oils and blends, in which induction time increased proportionally with the percentage of PO. However, induction time of 80% PO blend was similar to that of pure PO. Fatty acid composition appeared to be the most important factor affecting heat-oxidation stability and a saturated/unsaturated ratio near 1 was the optimally stable composition. Conversely, total phenols had a zero or negative role on the oxidative stability of the blends. Finally, in heat-oxidised oils significant losses of polyunsaturated fatty acids and formation of short-chain fatty acids were recorded.     

The antioxidant capacity and oxidative stability of virgin olive oil enriched with phospholipids

Virgin olive oil (VOO) enriched with phospholipids (soy lecithin) up to the levels present in seed oils (from 2.5 to 10.0 g/kg) was studied as a potential functional food. Lecithin addition slightly increased the concentration of tocopherols and considerably increased K270 values. In the fatty acid composition, an increase of linoleic and a slight decrease of oleic acid were observed, as the decrease of monounsaturated/polyunsaturated fatty acid ratio. The radical-scavenging activity was evaluated by two methods: electron spin resonance spectroscopy using galvinoxyl free radical and VIS spectroscopy measurement of the disappearance of 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical. Results indicate that lecithin addition retards the scavenging activity of VOO that is ascribed to the bipolar character of lecithin and its ability to entrap hydrophilic antioxidants. The effect of lecithin addition on the oxidative stability of VOO was evaluated by the Rancimat method, and a positive linear correlation (r = 0.9849) with induction time was found.     

Lipolytic yeasts distribution in commercial extra virgin olive oil

The olive oil lipase-producing yeasts can lower the quality of the product through the hydrolysis of the triacylglycerols. In this research the olive oil total yeasts were divided into five chromogenic groups, for each group the amount of the lipase-producing yeasts was evaluated and the more active isolates were classed. The trials showed the prevalence of more than three chromogenic yeast groups in the commercial poly-varieties of extra virgin olive oil mixture, whereas in the mono-varieties one, no more than one chromogenic yeast group prevailed according to the olive variety. The ratio of the lipase-producing yeast varied from 33% in the smooth brown chromogenic group to 83% in the wrinkly bluish one. The physiological and genetic analyses of the more active lipase-producing yeast belonging to each chromogenic group allowed us to classify the wrinkly red 1892 strain and the wrinkly bluish 1890 strain as Candida parapsilosis, whereas the smooth white 1885 strain was classed as Candida wickerhamii. The ribosomal (26S) D1/D2 region sequencing results of the wrinkly white 1886 strain and the smooth brown 1887 strain are not identical to that of any known yeast species. They showed 8 substitution and 11 substitution plus 2 indels, respectively, different from Pichia mexicana and Pichia minuta. This is the first report where the human pathogen C. parapsilosis species was found in commercial extra virgin olive oil. The chromogenic group evaluation permitted the rapid preliminary identification of technological and human health important olive oil yeasts.     

Distribution of dimorphic yeast species in commercial extra virgin olive oil

Recent microbiological research has demonstrated the presence of a rich microflora mainly composed of yeasts in the suspended fraction of freshly produced olive oil. Some of the yeasts are considered useful as they improve the organoleptic characteristics of the oil during preservation, whereas others are considered harmful as they can damage the quality of the oil through the hydrolysis of the triglycerides. However, some dimorphic species can also be found among the unwanted yeasts present in the oil, considered to be opportunistic pathogens to man as they have often been isolated from immunocompromised hospital patients. Present research demonstrates the presence of dimorphic yeast forms in 26% of the commercial extra virgin olive oil originating from different geographical areas, where the dimorphic yeasts are represented by 3–99.5% of the total yeasts. The classified isolates belonged to the opportunistic pathogen species Candida parapsilosis and Candida guilliermondii, while among the dimorphic yeasts considered not pathogenic to man, the Candida diddensiae species was highlighted for the first time in olive oil. The majority of the studied yeast strains resulted lipase positive, and can consequently negatively influence the oil quality through the hydrolysis of the triglycerides. Furthermore, all the strains showed a high level of affinity with some organic solvents and a differing production of biofilm in “vitro” corresponded to a greater or lesser hydrophobia of their cells. Laboratory trials indicated that the dimorphic yeasts studied are sensitive towards some components of the oil among which oleic acid, linoleic acid and triolein, whereas a less inhibiting effect was observed with tricaprilin or when the total polyphenols extracted from the oil were used. The observations carried out on a scanning electron microscope (SEM), demonstrated the production of long un-branched pseudohyphae in all the tested dimorphic yeasts when cultivated on nutrient-deficient substrates.     

添加新鲜橄榄叶和复合果胶酶压榨对油橄榄果出油率和初榨橄榄油品质的影响

为提高油橄榄果出油率、改善初榨橄榄油(VOO)品质,以甘肃陇南主栽的成熟度为7的莱星品种油橄榄鲜果为原料,考察压榨过程中新鲜橄榄叶(0、3%、5%)和复合果胶酶(0、0.01%、0.02%)添加量(以油橄榄果质量计)对油橄榄果出油率和VOO色泽、叶绿素含量、基本理化性质、总酚含量、脂肪酸组成及含量的影响。结果表明：添加适量的新鲜橄榄叶可提高出油率及总酚含量,降低酸值,但色泽加深,叶绿素含量和过氧化值升高;添加适量的复合果胶酶在提高出油率的同时,VOO的总酚含量上升,叶绿素含量和过氧化值降低,但酸值升高,色泽加深;压榨过程中添加新鲜橄榄叶和复合果胶酶对VOO脂肪酸组成没有影响,但对油酸、亚油酸、棕榈酸和棕榈烯酸等主要脂肪酸含量有一定影响。在压榨制取VOO时添加适量的新鲜橄榄叶与复合果胶酶可提高出油率,获得富含多酚的VOO。     

不同品种与加工工艺对初榨橄榄油挥发性风味成分的影响

采用热脱附-气相色谱-质谱联用技术对9个单品种初榨橄榄油挥发性风味成分进行分析。9个单品种初榨橄榄油共鉴定出22种挥发性风味成分,相对含量较高的有(E)-2-己烯醛、正己醛、2-己烯醛、叶醇、1-戊烯-3-酮,其中(Z)-2-庚烯醛仅在鄂植8号和阿斯品种中检出,乙酸己酯只在莱星和城固32号品种中检出,正戊醇仅在鄂植8号品种中检出,皮瓜尔和阿斯品种中未鉴定出(E)-2-己烯-1-醇和2-乙基己醇。莱星、城固32号单品种初榨橄榄油随着油橄榄成熟度的增大,(E)-2-己烯-1-醇、正己醇相对含量明显升高,而1-戊烯-3-醇相对含量显著降低。莱星单品种油橄榄加酶提取的橄榄油特有成分为(E,E)-2,4-庚二烯醛,鄂植8号单品种特有成分有柠檬烯、正戊醇、(Z)-2-庚烯醛、(E)-2-己烯-1-醇、(E,E)-2,4-庚二烯醛、2-乙基己醇。结果说明,9个单品种初榨橄榄油挥发性风味成分在相对含量和成分组成上均存在差别;同一品种不同成熟度的油橄榄获取的初榨橄榄油,香气成分不同,不同品种初榨橄榄油挥发性成分随成熟度的变化规律基本一致,加酶提取工艺较佳,可丰富初榨橄榄油香气。     

Influence of the malaxation time and olive ripening stage on oil quality and phenolic compounds of virgin olive oils

The main objective of this study was to evaluate the influence of the malaxation time (Mt) and ripening stage on oil quality and phenolic compounds of Hojiblanca and Picual virgin olive oils. In both varieties of oil, phenolic content and oxidative stability decreased as ripening progressed. The total level of tocopherols diminished by up to 40% as fruit ripened. The compositions of palmitic, stearic, lignoceric, oleic, linoleic and linolenic acids were significantly influenced by the ripening process. The present work shows that an increased Mt promoted the increase of free acidity (up to 13.3%) and tocopherols (up to 11.6%) and negatively affected the oxidative stability and the concentration of phenols. Further research is required to determine ripening stages and malaxation conditions for all olive oil varieties to achieve a satisfactory balance between the improvement of both oil yield and oil quality and composition.     

Differential scanning calorimeter application to the detectionof refined hazelnut oil in extra virgin olive oil

The potential application of differential scanning calorimetry (DSC) to verify adulteration of extra virgin olive oil with refined hazelnut oil was evaluated. Extra virgin olive oil and hazelnut oil were characterised by significantly different cooling and heating DSC thermal profiles. Addition of hazelnut oil significantly enhanced crystallisation enthalpy (at hazelnut oil ?20%) and shifted the transition towards lower temperatures (at hazelnut oil ?5%). Lineshape of heating thermograms of extra virgin olive oil was significantly altered by hazelnut oil addition: a characteristic exothermic event originated at −27 °C in extra virgin olive oil and progressively disappeared with increasing hazelnut oil content, while the major endothermic peak at −3.5 °C broadened (at hazelnut oil ?40%) and the minor endothermic peak at 8 °C shifted toward lower temperatures (at hazelnut oil ?5%). The preliminary results presented in this study suggest that DSC analysis may be a useful tool for detecting adulteration of extra virgin olive oil with refined hazelnut oil.