【作者】 龙奇志；

【导师】 李忠海；

【作者基本信息】 中南林业科技大学 ， 林产化学加工工程， 2012， 博士

【摘要】 茶油是世界四大木本油脂之一。特别是在中国和日本有长期食用的历史。茶油含单不饱和脂肪酸,与橄榄油较为接近。但是,由于其分布具有明显的地域性,对其品质,特别是感官品质等的研究较少。本研究主要是对焙烤、脱色及煎炸等茶油加工精炼和使用过程中的品质变化进行研究,特别是对挥发性成分及酚类物质的分析方法及变化进行研究。固相微萃取目前被广泛地用来测定液态、气态,甚至固态物质的挥发组分,不同待测物的性质决定了萃取头的种类选择。本文采用4种常用的SPME涂层萃取头(100μmPDMS、85μmPA、65μmPDMS/DVB、50/30μmDVB/CAR/PDMS)对茶油挥发物的提取性能进行了比较研究,结果表明：65μmPDMS/DVB萃取头对较高沸点物质,如苯甲醛、正辛醛、正辛醇、正壬醛、正壬醇的吸附比50/30μmDVB/CAR/PDMS萃取头要灵敏,但50/30μmDVB/CAR/PDMS萃取头对较低沸点物质的吸咐要灵敏很多。DVB/CAR/PDMS涂层萃取头所得的总峰面积的平均值最大,其余依次是PDMS/DVB、PA、PDMS; DVB/CAR/PDMS、PDMS/DVB、PA、PDMS对挥发物吸咐总峰面积与挥发物总量之间存在线性关系,其相关系数(R2)分别是0.9939、0.9888、0.9176、0.9917。因此,65μm PDMS/DVB和50/30μm DVB/CAR/PDMS的萃取头较适用于茶油挥发物的提取。在建立茶油主要挥发性成分定量分析方法的基础上,采用顶空固相微萃取(HS-SPME)、气相色谱-质谱(GC-MS)联用,测定了液压机榨茶油的挥发性成分。结果显示：13种茶油主要挥发物的浓度与峰面积间呈现出良好的线性关系,相关系数(R2)在0.9840～0.9999之间,检测限为0.04μg/g～0.43μg/g,加标回收率为90.88%～105.03%,并有较好的重现性,7次连续检测的相对标准偏差范围在3.66%～7.42%。液压机榨茶油毛油中的挥发性成分主要为醛类、醇类、烯类、酮类、酯类、酸类等。挥发性物质含量在前10位的是壬醛、α-蒎烯、乙酸乙酯、戊醇、苯甲醛、辛醇、α-木罗烯、壬醇、癸醇、辛醛,其含量总和为21.26μg/g,占总量的68.40%。此法对茶油挥发性成分的分析能达到快速、方便及准确的要求。综合茶油感官、GC、GC/MS的分析结果,在大量查阅参考文献的基础上,计算了主要呈味物质的气味活性值(OAV)。选定10种主要呈味物质作为主体成分,按不同浓度和增加部分可能的呈味物质,构建了20余个配方,结合感官鉴定筛选出的机榨毛油作为对照,进行了三点检验和GC分析,从中筛选了2个配方,与机榨毛油无显著差别(p>0.05)。油茶籽种仁的焙烤和水代法制油工艺条件的优化结果表明：以茶油出油率及清油率为指标来评价工艺,油茶籽仁的焙烤适宜温度与时间分别为175℃和15min；水代法分离的合适条件为水料比为4.5：1,分离时间为150min。茶油中的水分与挥发物含量、过氧化值随焙烤温度与时间的增加而下降,而碘值和皂化值变化则有相反的规律；酸值则没有明显的规律性变化。用该法提取的茶油挥发性成分分属于醛类、醇类、酯类等物质,含量最高的是乙酸乙酯。大多数挥发性成分在170℃时积累到较高水平,并随温度的进一步升高而下降,但随焙烤时间的增加,多数成分都有增加的趋势。为了了解茶油在脱色过程中的质量变化及氧化状态,测定了过氧化值、酸值、紫外吸收和挥发物的组成。结果表明：在白土用量0%-4%,脱色时间0-40min,脱色温度为110℃的条件下,FFA、K270、K232随白土用量和时间的增加而增加,而过氧化值则下降。当脱色温度和时间分别在110℃和30min时,白土用量从0%上升到4%,不同挥发物上升到：醛类(23.7μg/g)、醇类(13.2μg/g)、酯类(8.0gg/g)、烷类(2.0μg/g)和酮类(1.9μg/g)。同时,脱色温度为110℃,白土用量为3%时,脱色时间从0上升到40min,不同挥发物增加到：醛类(27.7gg/g)、醇类(18.2gg/g)、酯类(7.3μg/g)、烷类(0.6μg/g)和酮类(3.2μg/g)。这说明脱色可以分解氢过氧化物,并由白土用量和时间所控制。以棕榈油作为对照,采用精炼茶油进行深层煎炸,分析测定了煎炸用油脂及薯条中油脂在煎炸过程中的主要化学指标,即酸值、过氧化值、羰基价、碘价、皂化值、K值及极性化合物含量等的变化；分析了煎炸用茶油的挥发性成分的变化；评价了薯条的感官品质。结果表明：在连续煎炸30h(120批次),茶油及棕榈油的酸值、过氧化值、羰基价、极性化合物含量和K值均逐渐升高,碘价和皂化值则呈逐渐降低的趋势；总挥发物含量逐渐增加,但一些小分子量挥发物呈先升后降的趋势；用新鲜油煎炸的薯条的总体得分较高；除过氧化值以外,薯条中茶油的其他测定指标的变化滞后于煎炸用油的变化。对照GB7102,除茶油的羰基价在24h时已超标外,其他指标至30h时尚处于规定的限值范围。因此,茶油的深层煎炸寿命为24h(96批次),用茶油煎炸的薯条更易被消费者所接受。实验室制备的浸出毛油(SECO)和市购的冷榨油(CPO)用于分析总酚含量(TP)和其他质量指标。同时考察了不同溶剂提取对多酚组成的影响。根据GB11765,冷榨油的酸值、过氧化值和透明度、气味滋味等能满足要求,但SECO则略显混浊。两种油在总酚含量上没有明显的差别,但浸出油的多酚组成明显要比冷榨油复杂得多。提取溶剂的效果表明：低级醇比丙酮能提取更多的多酚种类,丙酮仅能提取没食子酸。这说明浸出毛油必须进行精炼,不同溶剂提取效果的针对性可能对今后的多酚研究有一定的借鉴作用。更多还原

【Abstract】 Camellia is one of the four main oil-bearing trees (palm, coconut, olive and tea) in the world. The oil from camellia seeds has long been important in China and Japan, to a lesser extent. Camellia oil with its low saturated fatty acid and high monunsatuarted oleic acid content is a natural competitor for olive and grape seed oils. Since it has regional property, the attributes and their changes during processing and cooking of camellia oil, particularly, sensory and nutritional properties have not been surely understood. In this study, the quality changes during roasting, bleaching and frying were investigated. Actually, the quantitative analyses and changes of polyphenols and volatiles as minor compounds in camellia oil were the highlights in the study.Solid Phase Microextraction (SPME) has been widely used for extraction of volatile in gas, liquid and solid matrices. Four fibers, i.e.100μmPDMS,85μmPA,65μmPDMS/DVB and50/30μmDVB/CAR/PDMS, were selected for extraction in camellia oil volatile analysis. The results showed that:1) benzaldehyde, octanal, octonol, nonanal, and nonanol which have relatively higher boiling points were sensitive in65μm PDMS/DVB fiber, while the relative lower boiling point compounds were sensitive in50/30μm DVB/CAR/PDMS fiber;2) the total peak areas in gas chromatography ranked as following sequence:DVB/CAR/PDMS>PDMS/DVB>PA>PDMS;3) linear regressive relationship between total peak area and volatile amount (0-120μg/g) in DVB/CAR/PDMS, PDMS/DVB, PA, PDMS was existed with R2of0.9939,0.9888,0.9176and0.9917, respectively; These factors indicate that65μm PDMS/DVB and50/30μmDVB/CAR/PDMS are suitable for extraction of volatile of camellia oil.A method for volatile analysis of hydraulic pressed camellia oil(Camellia oleifera Abel) by headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) using50/30μm DVB/CAR/PDMS fiber is presented. Calibration curves were constructed for13compounds commonly reported in camellia oil headspace with coefficients of determination (R2) ranging from0.9840to0.9999and limits of detection (LOD) from0.04μg/g to0.43μg/g. The recoveries and coefficient of standard deviation in repetitive determination ranged from90.88%to105.03%and from3.66%to7.42%, respectively.37volatile compounds in hydraulic pressed camellia oil were identified by mass spectrum and standard retention time that included aldehydes, alcohols, ketons, esters and acids etc. The total concentration of the top ten compounds, namely, hexanal, a-pinene, ethyl acetate, pentanol, benzaldehyde, octanol, a-Muurolene, nonanol, decanol, and octanal, reached21.26μg/g and accounted for68.40%of total. These factors indicate that this method is rapid, sensitive and convenient for volatile analysis of camellia oil.Combined with the results of sensory evaluation and GC/MS analysis for camellia oil, odour active values (OAV) for interested compounds were calculated through the thresholds in references. About10compounds were selected as main aromatic volatiles according to OAVs to form about20formula by diffenrent concentrations and adding potential compounds for contributing aroma.2formula were confirmed through triangle test compared to hydraulic pressed oil(p>0.05).Results of optimization of roasting and aqueous extraction conditions showed that:1) the optimum extracted rate and oil yield could be got when camellia seed kernel was roasted at175℃for15min followed by separation using water (water/meal,4.5/1) for150min.2) the moisture and volatile content, PV decreased but IV and SV increased with the enhancement of time and temperature of roasting.3) the volatiles in camellia oil extracted by the above method were classified into aldehyde, alcohol and ester. Among them, ethyl acetate ranked first. Majority of these compound accumulated up to the highest level at170℃and decreased when temperature further increased. But the concentrations of most of compounds increased with the increase of roasting time.In order to understand the quality change and oxidative state of camellia oil(Camellia oleifera Abel) in the bleaching step, measurements of various quality parameters, i.e. peroxide value (POV), free fatty acid (FFA) and UV absorbance, and volatile profile of crude and bleached oils were carried out. The results showed that FFA, K270and K232increased, whereas POV decreased, with increase of the activated earth dosage of0-4%and of bleaching time from0to40min at110℃. As the amount of activated earth was increased from0%to4%with bleaching at110℃for30min, various classes of volatile compounds increased in concentration:aldehydes (23.7μg/g), alcohols (13.2μg/g), esters (8.0μg/g), alkenes (2.0μg/g) and ketones (1.9μg/g). Likewise when bleaching was carried out at110℃with3%activated earth, and the bleaching time varied between0and40min, concentrations of volatile compounds also increased:aldehydes (27.7μg/g), alcohols (18.2μg/g), esters (7.3μg/g), ketones (3.2μg/g) and alkenes (0.6μg/g). These findings indicate that hydroperoxides in oil were decomposed into lower molecular weight products in the process of bleaching and that the extent of this decomposition can be controlled by time and amount of activated earth.Refined camellia (GB11765, pressed oil, Grand1) was used for deep frying for French fryer with comparison of palm oil. During30h (120batches) frying procedure, acid, peroxide, carbonyl, iodine, saponification, and K values and polar compounds of frying oil and oil extracted from French fryer were analysed. Volatile of frying oil and sensory attributes of French fryer were also evaluated. The results were showed that acid, peroxide, carbonyl, and K values and polar compounds of camellia and palm oils increased gradually, while iodine and saponification values decreased; Total volatile accumulated with a trend of "up-down" of lower molecular weight volatiles; Total score of French fryers fried with fresh oil and with camellia oil were higher than those from the latter bathches and fried with palm oil; Except of peroxide value, other values assessed in the oil extracted from French fryer were lower than those in the relative batch frying oil. According the regulation of GB7102, except that carbonyl value at24h exceeded the limit, other indices were still within the required limit. The factors as given above indicate that the frying life of camellia oil should be24hours and the French fryer fried with camellia oil could be more acceptable by consumers.A claim of a camellia oil healthcare benefit as a result of the high amount of’tea polyphenol’arises a widely discussion in China currently, A laboratory solvent extracted crude oil (SECO) and a commercial cold pressed oil (CPO) were used for evaluation of oil attributes, particularly, total phenol content (TP). Effects of different solvents on phenol extraction for phenol profile were also investigated. According to GB11765(a Chinese standard for camellia oil quality), acid value (AV), peroxide value (POV), sensory attributes, i.e. transparency, odour and flavour of CPO met the requirements, while SECO showed turbid. TP in SECO had no significant difference compared with that in CPO, thus, the phenol profile of SECO seemed to be more complicated in comparison to that of CPO. Different solvents showed different effects on phenol profiles: low molecular alcohol aqueous solution could extract more phenolic compounds, while gallic acid as a solely coumpound was extracted by acetone. These factors indicate that SECO should be refined and solvent effect on phenolic compound extraction would be helpful on further research for the interested phenol fraction in camellia oil.更多还原