基于荧光光谱的初榨椰子油掺假检测技术研究

分析初榨椰子油、葵花籽油、玉米油和大豆油的荧光特性,建立SIMCA和PLS-DA判别分析模型,进行初榨椰子油的掺假检测分析研究。结果发现,初榨椰子油与葵花籽油等高不饱和型植物油的荧光特性具有显著性差异,且掺假初榨椰子油的荧光强度与掺假质量分数具有较强的相关性。采集350~400 nm的荧光光谱建立判别分析模型,结果显示,PLS-DA模型具有较好的判别分析能力,其对初榨椰子油中葵花籽油、玉米油和大豆油的掺假识别率分别为96%,90%和93%,该方法可以进行初榨椰子油掺假检测,具有无需前处理、快速、简便、易操作等特点。     

初榨椰子油加工技术的研究进展

初榨椰子油是从成熟椰肉中提取的可食用油脂,在护肤护发、减肥、调节脂质代谢、维护心血管健康等方面具有显著功效,是近年来健康食品中的明星产品,市场消费规模也越来越大。加工技术与工艺是影响椰子油品质的关键因素,国内外学者除了在对传统干法和湿法加工技术进行优化升级外,在初榨椰子油的新型加工技术和工艺方面加大研究力度如超临界二氧化碳技术,也在油脂的营养功能价值挖掘等方面进行了深入探索。本文旨在归纳总结近年来初榨椰子油的加工工艺、油脂品质和功能特性等方面的国内外研究进展情况,以期为广大从业者和相关科研工作者提供参考和借鉴。     

冷压初榨椰子油对四氯化碳致小鼠 急性肝损伤的保护作用

研究了冷压初榨椰子油对四氯化碳（CCl4）诱导昆明小鼠急性肝损伤的保护作用。将72只昆明小鼠随机分成6组,包括正常组、四氯化碳肝损伤模型组、联苯双酯组（150 mg/kg）、椰子油低剂量组（5 mL/kg）、椰子油中剂量组（10 mL/kg）、椰子油高剂量组（20 mL/kg）,通过测定小鼠血清中丙氨酸转氨酶（ALT）、天冬氨酸转氨酶（AST）、乳酸脱氢酶（LDH）、甘油三酯（TG）和总胆固醇（TC）指标,肝组织中超氧化物歧化酶（SOD）活力、谷胱甘肽过氧化物酶（GSH-Px）活力及丙二醛（MDA）含量,采用HE染色切片对小鼠肝脏组织进行病理学检查,考察冷压初榨椰子油对四氯化碳致小鼠急性肝损伤的保护作用。结果表明：与模型组相比,不同剂量组的冷压初榨椰子油（5、10 mL/kg和20 mL/kg）可以不同程度地降低小鼠血清中ALT、AST、LDH、TG、TC水平以及肝组织中MDA含量,提高肝组织中SOD活力与GSH-Px活力;同时,肝脏组织病理学观察与生化指标检测结果一致。其中,高剂量的冷压初榨椰子油(20 mL/kg)作用效果优于阳性对照联苯双酯。研究表明冷压初榨椰子油对肝脏具有较好的保护作用,作用机制可能与其含有较多的抗氧化物质以及功能性物质有关。     

HS-SPME-GC-MS结合多元统计分析初榨椰子油常温储藏过程中挥发性风味成分

为了研究初榨椰子油常温储藏过程的挥发性风味成分变化规律,采用顶空固相微萃取-气相色谱-质谱(Headspace solid phase microextraction and gas chromatography-mass spectrometry,HS-SPME-GC-MS)技术对不同氧化时期的初榨椰子油进行了分析。结果表明:共鉴定出40种挥发性成分（8个共有组分）,主要包括酯类、醛类、酮类和酸类。相对气味活度值（Relative odor activity value,ROAV）分析表明己醛、2-庚酮、丁位己内酯、壬醛、辛酸乙酯、丁位辛内酯、2-十一酮、癸酸乙酯、丁位癸内酯等是初榨椰子油常温储藏过程中关键风味物质。结合主成分分析（principal component analysis,PCA）及偏最小二乘判别分析（partial least squares discrimination analysis,PLS-DA）建立了初榨椰子油不同储藏时期的判别模型,表明除不同类别化合物（酮类化合物、酯类化合物和酸类化合物）的含量可以作为简单区分初榨椰子油储藏期的指标以外,至少六种关键挥发性成分（2-庚酮、2-己酮、丁位己内酯、己醛、己酸、丁位辛内酯）也可用于评估初榨椰子油的氧化情况。相关研究为初榨椰子油风味品质评价及氧化程度提供了理论参考,研究结果也有助于开发一种鉴别不同新鲜程度椰子油品的新方法。     

初榨椰子油品质特征及健康功效的研究进展

初榨椰子油（VCO）是近年来备受关注的功能性油脂。随着VCO市场的增长,对VCO功效的报道也越来越多,然而近年来对椰子油的功效有一定的争议。为了正确认识椰子油,促进VCO在大健康领域的推广应用,介绍了VCO的加工工艺、感官特征、质量指标、脂肪酸组成及微量活性成分,并对VCO的抗氧化、抗菌、抗病毒、抗炎等健康功效及其在心血管疾病、糖尿病、阿尔茨海默病、肥胖、肿瘤等疾病防治方面的研究进展进行了综述。VCO是一种具有一定健康功效的功能性油脂。     

羟丙基甲基纤维素和黄原胶浓度对初榨椰子油乳液及其模板油凝胶构建的影响

本实验采用乳液模板法制备了不同羟丙基甲基纤维素（HPMC）和黄原胶（XG）浓度的初榨椰子油凝胶，对所得乳状液和油凝胶进行了粒径分析、微观结构观察、流变测定、油损失和X-射线衍射（XRD）分析，探讨HPMC和XG浓度对初榨椰子油凝胶形成和物理性能的影响。微观结构和粒径分析结果表明:高浓度HPMC具有较好的乳化性能，获得油滴粒径较小的稳定乳液；XG浓度变化对油滴粒径的影响不显著。流变学结果表明:随着HPMC或XG浓度的增加，乳状液和油凝胶的机械强度也得到提高，所有油凝胶都表现出对时间的依赖性和结构的回复性。油损失结果表明:HPMC浓度的增加对油凝胶损失的影响尤为明显，变化幅度从19.6%降低为3.6%；XG浓度的增加也使油损失从9.62%降低为4.4%。但HPMC和XG浓度的变化对油凝胶的XRD图谱影响不明显。本实验为初榨椰子油凝胶的构建提供了理论基础，也为其实际应用提供了参考。     

椰子油复合凝胶软糖的配方优化及贮藏时间对质构的影响

为拓宽椰子油的应用，本实验以初榨椰子油、明胶、果胶等为材料制作混合型凝胶软糖，以感官评分为指标，在单因素实验的基础上，通过正交试验，对椰子油复合凝胶软糖的配方进行优化，并研究了贮藏时间对其质构的影响。实验结果显示，椰子油复合凝胶软糖的最佳配方为：椰子油9.44 g，糖总量34.00 g，凝胶胶液总量35.89 g，其中麦芽糖、木糖醇、黑糖质量比为24:5:5、总糖与总胶质量比为36:38、椰子油与糖胶质量比为10:74。在此配方下制备的椰子油复合凝胶软糖椰香浓郁、弹牙顺滑不粘腻，甜味恰当，感官评分为(84.22±1.17)分。质构仪分析结果显示，随着贮藏时间的延长，椰子油复合凝胶软糖的硬度、胶黏性和咀嚼性极显著提升(P<0.01)，但弹性无显著变化(P>0.05)。本研究可以为椰子油的综合开发利用提供参考依据。     

初榨橄榄油在加热过程中品质变化研究

初榨橄榄油营养丰富且具保健价值，研究初榨橄榄油在烹调加热过程中品质的变化具有重要意义。采用仪器分析和化学分析法研究初榨橄榄油在加热过程中品质指标的变化。研究结果表明，初榨橄榄油在180℃加热过程中，脂肪酸值、过氧化值、羰基值、黏度逐渐增加，饱和脂肪酸和反式脂肪酸含量增加，不饱和脂肪酸含量下降。初榨橄榄油在180℃加热300 min时，过氧化值开始超标；加热480 min时，脂肪酸值、羰基值、反式脂肪酸含量仍未超标或超过推荐量。初榨橄榄油在180℃下加热烹调食品不宜超过240 min。如果要延长烹调加热时间，可以适当降低加热温度。该研究为初榨橄榄油在食品中的煎炸及含初榨橄榄油食品的高温处理提供科学参考。     

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。     

28份国产特级初榨橄榄油中多酚含量及其变化规律北大核心CSCD

为了对我国油橄榄产业提供基础数据支持,采用国际油橄榄理事会推荐的HPLC法检测特级初榨橄榄油中的多酚含量,分析了我国不同产地的28份市售食用特级初榨橄榄油样品的多酚含量,并对不同生产年度和不同产地单果级特级初榨橄榄油中多酚含量变化规律进行了分析。结果表明:市售国产特级初榨橄榄油中均含有较为丰富的多酚类化合物,多酚含量范围为(63.885±2.345)mg/kg~(307.325±6.865)mg/kg;特级初榨橄榄油中多酚含量受贮存时间的影响较大,同时不同产地中适合生产高多酚含量特级初榨橄榄油的品种具有差异。不同特级初榨橄榄油样品之间多酚含量波动较大,需要通过多种方法来防止油脂中多酚类化合物的降解,以保证油品的质量,并因地制宜对油橄榄品种进行优化筛选。     

原生态椰子油的功能性质及应用

原生态椰子油是国外市场非常流行的一种新型功能性植物油脂,在国内还没有产品出现。由于加工方式温和,原生态椰子油保留了更多有益的功能性成分,因此比椰子油具有更优越的功能性质。详细介绍了原生态椰子油的优点、功能性质、应用领域及市场前景。     

MONITORING THE ADULTERATION OF VIRGIN COCONUT OIL BY SELECTED VEGETABLE OILS USING DIFFERENTIAL SCANNING CALORIMETRY

The crystallization and melting enthalpy of virgin coconut oil adulterated with palm kernel oil (PKO) and soybean oil (SBO) were studied by using differential scanning calorimetry. Virgin coconut oil was spiked separately with PKO and SBO from 2% to 40% (w/w) of adulterant oils. Fatty acids of all oils were determined to complement the differential scanning calorimetry data. The heating curve of SBO-adulterated samples showed the adulteration peak appearing at the lower temperature region at 10% adulteration level. Regression analyses using stepwise multiple linear regression were used to predict the percentage adulterant with R ² of 0.9490. PKO-adulterated oils did not show any adulteration peak but demonstrated a gradual decrease in the peak height of the major exothermic peak.

PRACTICAL APPLICATIONS

An alternative method for detection of adulteration based on differential scanning calorimetry in virgin coconut oil is presented. Application of differential scanning calorimetry is rapid, does not require sample preparation and does not involve use of solvents or toxic chemicals.     

Acrylamide formation in a cookie system as influenced by the oil phenol profile and degree of oxidation

The purpose of this study was to investigate the effect of the olive oil phenolic compounds as well as of thermoxidised oil on the formation of acrylamide in a cookies system. Three virgin olive oils having different phenolic profile and a thermoxidised sunflower oil were selected. Cookies were baked at 190 °C for different times (8–16 min) following a basic recipe where type of oil was the variable. Additionally to acrylamide (AA), other parameters such as colour, moisture, antioxidant activity (AOA), and hydroxymethylfurfural (HMF) were measured. Results showed that concentration and composition of phenolic moiety of virgin olive oil significantly affect the acrylamide formation, particularly at prolonged baking time. Virgin olive oil with a higher dihydroxy/monohydroxy ratio was more efficient in the AA mitigation and AA was reduced up to 20%. Colour and AOA were not significantly different among the three types of oils. However, AA is dramatically increased when thermoxidised oil is used with a parallel increase of browning and HMF. It was concluded that lipid oxidation products should be considered as an important factor in acrylamide formation during baking of fat-rich products.     

Comparison of the phenolic-dependent antioxidant properties of coconut oil extracted under cold and hot conditions

The antioxidant activities of coconut oil extracted under hot and cold conditions were compared. The coconut oil extracted under hot conditions (HECO) contained more phenolic substances than the coconut oil extracted under cold conditions (CECO). The antioxidant potential of HECO was higher than that of CECO as demonstrated by DPPH assay, deoxyribose assay and in vivo assay of serum antioxidant capacity. It is the common belief that virgin coconut oil extracted under cold conditions preserves several thermally unstable antioxidants and, as a result, better beneficial qualities can be expected for virgin coconut oil. However, high temperatures used in the hot extraction of coconut oil favour the incorporation of more thermally stable phenolic antioxidants into coconut oil. Therefore, the consumption of HECO may result in the better improvement of antioxidant related health benefits compared with the consumption of CECO.     

Coconut Milk and Coconut Oil: Their Manufacture Associated with Protein Functionality

Coconut palm (Cocos nucifera L.) is an economic plant cultivated in tropical countries, mainly in the Asian region. Coconut fruit generally consists of 51.7% kernel, 9.8% water, and 38.5% shell. Coconut milk is commonly manufactured from grated coconut meat (kernel). Basically, coconut milk is an oil‐in‐water emulsion, stabilized by some proteins existing in the aqueous phase. Maximization of protein functionality as an emulsifier can enhance the coconut milk stability. In addition, some stabilizers have been added to ensure the coconut milk stability. However, destabilization of emulsion in coconut milk brings about the collapse of the emulsion, from which virgin coconut oil (VCO) can be obtained. Yield, characteristics, and properties of VCO are governed by the processes used for destabilizing coconut milk. VCO is considered to be a functional oil and is rich in medium chain fatty acids with health advantages.     

Aroma and physical characteristics of cakes prepared by replacing margarine with extra virgin olive oil

The effect of margarine substitution by extra virgin olive oil on the quality of Madeira cakes was studied. Three cakes containing either extra virgin olive oil or extra virgin olive oil/margarine mixture or margarine were prepared. The use of extra virgin olive oil increased batter density and cake volume while decreased the weight loss (%) during baking. Texture profile analysis also showed that the replacement of margarine by extra virgin olive oil affected significantly hardness and cohesiveness of the cakes. Headspace solid phase microextraction was applied in order to analyze the aroma of the three cakes. The addition of extra virgin olive oil produced a wide range of volatile compounds, which were analyzed by gas chromatography/mass spectrometry and were originated either from extra virgin olive oil or were produced during the baking process. Hedonic sensory tests were also conducted revealing that the cake prepared with extra virgin olive oil/margarine mixture was highly appreciated by the consumers as it got scores similar to control.     

Chemical and functional properties of fibre concentrates obtained from by-products of coconut kernel

The coconut kernel residues obtained after extraction of coconut milk (MR) and virgin coconut oil (VOR) were analysed for their potential as dietary fibres. VOR was defatted and treated chemically using three solvent systems to isolate coconut cell wall polysaccharides (CCWP).     

Characteristic volatiles fingerprints and profiles determination in different grades of coconut oil by HS-GC-IMS and HS-SPME-GC-MS

Coconut oil has been extensively used in the food industry, but determination of the quality of coconut oil remains challenging. In this study, volatile components of the coconut oils (refined, desiccated or virgin) subjected to different processing methods were identified and compared. Twenty-six volatile components exhibiting characteristic differences among the three types of coconut oil were screened using headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS). Furthermore, ethanol, 1-propanol and dimethyl ketone could only be determined by using headspace-gas chromatography–ion mobility spectrometry (HS-GC-IMS). The principal component analysis diagrams attained by the volatile component data demonstrated that the coconut oil samples could be clearly classified into three categories. The multivariate analysis results revealed 2-heptanone and hexanal to be the most promising markers in terms of grade discrimination in coconut oil. The findings are conducive to the development of a new method for the identification of oils with different refining degrees.