Comparative trials and an empirical model to assess throughput indices in olive oil extraction by decanter centrifuge

Interesting performance indices for a decanter centrifuge used in oil extraction from olive paste were found through an empirical black box approach to oil extraction using a decanter centrifuge validated with experimental data. The performance indices identified were: oil recovery efficiency, the separation coefficient and husk water content.     

Salt improves physical extraction of olive oil

The use of two concentrations of common salt (0.6 and 1.2%) as coadjuvant for the physical extraction of olive oil has been tested at a laboratory scale and compared with those tests which did not use a coadjuvant or used talc, the only coadjuvant that is allowed according to EC regulations, using the fruits of six different olive varieties (Olea europaea L. cvs. Arbequina, Hojiblanca, Lechín, Manzanilla, Picual, and Verdial). Common salt systematically allowed a higher oil yield than the controlled extraction without coadjuvants, with similar recovery rates to those values obtained when using the more expensive alternative of talc. Physico-chemical quality parameters of the virgin olive oils were not significantly affected by the use of this coadjuvant. However, the levels of oil stability, pigment content or intensity of bitterness were slightly increased. Salt addition seems to be a feasible alternative for the improvement of oil extraction. No appreciable advantages were observed when using the higher concentration of salt tested.     

《2015年国际橄榄油和食用橄榄协定》解析

《2015年国际橄榄油和食用橄榄协定》（International Agreement on Olive Oil and Table Olives, 2015）是国际商品协定的一种,由联合国于2015年10月9日在日内瓦万国宫谈判后通过。基于此组建的国际橄榄理事会（International Olive Council）是全球橄榄贸易领域的权威组织。该协定最早版本于1959年首签,2015年第六版有效期至2026年12月31日。本文介绍协定内容并就以下方面进行解释：国际橄榄理事会的工作目标,橄榄油和食用橄榄的有关名词术语,成员理事会的组成方式和行政机构,各成员国在理事会的参与份额计算方式。截止2020年成员国方面的变动为伊拉克退出,增加巴勒斯坦、格鲁吉亚两个国家,文中所列成员参与份额为2020更新的数据。另外2021年毛里塔尼亚有望同意签署2015年版本协定,正式加入该组织。了解和熟悉国际橄榄油和食用橄榄协定是中国橄榄油行业融入世界贸易外循环的前提条件。作为国际大宗初级产品的主要进口和出口国,本文介绍的橄榄油和食用橄榄协定的一般原则与组织方式值得借鉴,我国应当在其它初级产品贸易规则的标准制定方面掌握主动,发出更多中国声音,为完善全球治理做出中国贡献。     

总迁移量测试橄榄油提取次数的探究

目的 探究试样吸收橄榄油是否完全提取对橄榄油总迁移量测试结果的影响。方法 采用乙醚对迁移试验后的试样提取一次和三次两种不同方法进行总迁移量的测试。结果 乙醚提取一次的橄榄油总迁移量明显低于乙醚提取三次的橄榄油总迁移量。结论 进行橄榄油总迁移量测试时须保证试样吸收橄榄油的完全提取,以获得准确的测试结果。     

Horizontal centrifuge with screw conveyor (decanter): Optimization of oil/water levels and differential speed during olive oil extraction

Olive oil extraction using a horizontal centrifuge with a screw conveyor is an essential operation to reduce production costs. However, proper control of the plant is required to maintain a high level of extraction yield and olive oil quality. Rheological characteristics of the olive paste, which change in relation to water content, fruit variety, maturity level and seasonal temperature variations, greatly affect the efficiency of centrifugal extraction. If olive paste is fed to a decanter without automatic control, then non-optimal extraction is performed.     

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。     

Estimation of olive oil acidity using FT-IR and partial least squares regression

Olive oil characteristics are directly related to olive quality. Information about olive quality is of paramount importance to olive and olive oil producers, in order to establish its price. Real-time characterization of the olives avoids mixtures of high quality with low quality fruits, and allows improvement of olive oil quality. This work describes an indirect determination of olive acidity and that allows a rapid evaluation of olive oil quality. The applied method combines chemical analysis (30 min Soxhlet olive pomace extraction) in tandem with a spectroscopic technique (FT-IR) and multivariate regression (PLS1). The most suitable calibration model found used SNV pre-processing and was built with 4 Latent Variables giving a RMSECV of 8.7% and a Q² of 0.97. This accurate calibration model allows the estimation of olive acidity using a FT-IR spectrum of the corresponding Soxhlet oil dry extract and therefore is a suitable method for indirect determination of FFA in olives.     

Acephate and buprofezin residues in olives and olive oil

Field trials were carried out to study the persistence of acephate and buprofezin on olives. Two cultivars, pizz'e carroga and pendolino, with very large and small fruits respectively were used. After treatment, no difference was found between the two pesticide deposits on the olives. The disappearance rates, calculated as pseudo first order kinetics, were similar for both pesticides (on average 12 days). Methamidophos, the acephate metabolite, was always present on all olives, and in some pendolino samples it showed higher residues than the maximum residue limit (MRL). During washing, the first step of olive processing, the residue level of both pesticides on the olives did not decrease. After processing of the olives into oil, no residues of acephate or methamidophos were found in the olive oil, while the residues of buprofezin were on average four times higher than on olives.     

High throughput flow injection bioluminometric method for olive oil antioxidant capacity

This paper describes a rapid flow injection automated method for the determination of olive oil total antioxidant capacity. The chemistry involved is the horseradish peroxidase (HRP) catalysed oxidation of luminol by hydrogen peroxide. Oxidation results in light emission (bioluminescence) that is enhanced using p-iodophenol sensitizer. Olive oil (0.7 mL) is extracted with two 0.7 mL aliquots of 80–20% (v/v) methanol–water solvent. A 17 μL aliquot of the extract containing hydrophilic antioxidants is injected in a phosphate buffer channel that subsequently merges with a luminol–HRP–p-iodophenol reagent stream. Bioluminescence resulting after merging the mixture with a hydrogen peroxide stream is suppressed upon increasing antioxidants’ concentration resulting in negative peaks due to hydrogen peroxide consumption by antioxidants. The method has been optimized on (a) number of manifold channels, (b) flow rates, (c) coil length and (d) HRP, hydrogen peroxide and p-iodophenol concentrations. Detection limit is calculated at 1.5 × 10⁻⁷ M gallic acid, linear range is between 1.0 × 10⁻⁶ and 1 × 10⁻⁴ M and precision is better than 2.8% RSD (n = 4). The fully automated method is achieving a rate of sampling equal 180 probes per hour. The proposed method is applied for the assessment of 50 extra-virgin olive oil samples of different Greek cultivars and regions.     

Composition of total sterols (4-desmethyl-sterols) in extravirgin olive oils obtained with different extraction technologies and their influence on the oil oxidative stability

The composition and antioxidant activity of total sterols in extravirgin olive oils obtained with different extraction technologies from olives harvested at two ripening stages, were studied. The antioxidant activity was evaluated with an oxidative stability instrument (OSI), by using a model system (made of a mixture of treated/untreated commercial refined peanut oil) enriched with the total sterol fractions of the extravirgin olive oils. No correlation was found between the OSI time and the extraction technologies, the ripening stages or the actual amount of sterols added. No significant differences were observed in the percent composition of sterols of extravirgin olive oils produced with different technologies during the same harvesting period. The latter, however, had a significant effect on the percent of β-sitosterol and 5-avenasterol in extravirgin olive oils produced with the same technology.     

微波辅助提取辣木籽油的工艺研究

以辣木籽为原料,在单因素实验的基础上通过正交实验优化微波辅助提取辣木籽油的工艺条件,并将最佳条件下的辣木籽油得率及其品质与超声波辅助法、溶剂浸出法的进行对比分析。结果表明:微波辅助提取辣木籽油的最佳工艺条件为微波功率密度5 W/g、微波辐射时间6 min、提取温度50℃、提取时间30 min,在此条件下辣木籽油得率为36.45%;与超声波辅助法和溶剂浸出法相比,微波辅助法得率最高,所得辣木籽油的碘值最大,植物甾醇、多酚、黄酮含量最多,过氧化值最低,是一种应用前景广阔的辣木籽油提取方法。     

溶剂浸取法提取麻疯果仁油的工艺研究

采用溶剂浸取法提取麻疯果仁油,考察了浸取温度、浸取次数、液料比、浸取时间等因素对提油效果的影响。实验得到的最佳逆流浸取工艺条件为:浸取温度60℃,浸取级数5级,液料比8∶1,单级浸取时间1 h。在该工艺条件下,麻疯果仁油的提取率可达99.1%,脱溶后所得毛油酸值(KOH)在2.8~4.2 mg/g之间,可直接用作制备生物柴油的原料油。     

超声波和超高压辅助提取初榨橄榄油的工艺优化及效果比较

超声波和超高压是两种辅助提取植物油脂的技术,但这两种技术是否影响初榨橄榄油的出油率和品质尚未见报道。本研究采用超声波和超高压处理“Koroneiki”油橄榄鲜果果浆,在单因素筛选的基础上,采用正交实验优化了提取工艺,分析了处理对初榨橄榄油出油率、残油率以及理化指标的影响。结果表明,超声波处理最佳工艺条件为超声温度30℃,超声功率480W,超声时间1.5min,在此条件下初榨橄榄油的出油率可达到15.63%;超高压最佳工艺条件为处理温度40℃,处理压力300Mpa,保压时间3 min,在此条件下初榨橄榄油出油率可达15.98%;超声波和超高压处理显著提高了初榨橄榄油的出油率,降低了残油率。超声波和超高压处理对初榨橄榄油的酸价、过氧化值、皂化值及K232均未有显著影响,但提高了K270和ΔK值。综上,超声波和超高压处理可显著提高初榨橄榄油的出油率,对初榨橄榄油的酸价、过氧化值、皂化值及K232均无显著影响,但提高了K270和ΔK值,两处理的出油率和品质间无显著差异。     

酶的选择对水酶法提取核桃油的影响

研究了中性蛋白酶(PR)、中温淀粉酶(α-AM)、果胶酶(PE)和纤维素酶(CE)单独使用和两种复配使用、3种复配使用对总油和清油提取率的影响。结果显示,蛋白酶对清油提取率效果最好,纤维素酶作用次之;两种酶复配使用时,蛋白酶和纤维素酶复配清油提取率可达40%以上,淀粉酶与纤维素酶复配效果也较好;3种酶复配使用时,蛋白酶、纤维素酶与果胶酶的复配效果最好,淀粉酶、蛋白酶与纤维素酶的复配效果次之,但对清油提取率提高作用不大。     

Comparative study of different extraction techniques for the analysis of virgin olive oil aroma

Headspace solid-phase microextraction (HS-SPME), simultaneous distillation/extraction (SDE) and closed-loop stripping analysis (CLSA) coupled to gas chromatography/mass spectrometry (GC/MS) were used to study virgin olive oil, with the goal of detecting large numbers of characteristic volatile and semi-volatile compounds. More than one hundred compounds were detected in the olive oil extracts, and their percent amounts obtained by each technique were calculated. Qualitative and quantitative differences of virgin olive oil volatile profiles were observed applying the three extraction techniques. SPME showed a higher affinity for alcohols and ketones, while CLSA achieved the highest percentages of esters and hydrocarbons. Finally, the highest extraction of total terpenoid compounds occurred with SDE and CLSA, where CLSA allowed extracting the highest percentages of the most of them. SDE extraction caused the thermal degradation of the oil sample, which resulted in a high percentage of aldehydic compounds.     

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.     

南瓜籽油提取工艺优化及油脂氧化稳定性研究

以南瓜籽为原料,研究溶剂浸提法提取南瓜籽油最佳工艺。研究了温度、时间和料液比3个因素对提取率影响,并且通过正交试验对溶剂浸提法提取南瓜籽油工艺流程进行了优化。最佳提取条件:提取温度55℃,时间3 h,料液比1∶10时,提取率可达93.4%。