A novel process for extraction of tea oil from Camellia oleifera seed kernels by combination of microwave puffing and aqueous enzymatic oil extraction

The objective of this study was to extract the oil from Camellia oleifera seed kernels by aqueous enzymatic oil extraction (AEOE). We describe a novel process for extraction of tea oil preceded by tea saponin extraction from C. oleifera seed kernels. The extraction efficiency obtained with microwave‐assisted extraction (MAE) is very high, which the recovery yield is up to 83% in 30 s and the saponins in camellia seed kernels can be completely removed by the second MAE. Moreover, an important step in the process development has been the pretreatment by microwave puffing of camellia seed kernel residues followed by AEOE increased oil extraction yield from 53% to 95%, which will is comparable to hexane oil extraction yields from plant materials.     

A Tea Saponin-Carbohydrate-Protein Complex Could Be One Key Emulsifiable Compound in the Emulsion Formed during Aqueous Extraction of Camellia Oil

The oil/water (O/W) emulsions are spontaneously formed during the process of aqueous extraction of camellia oil which indicates that there are natural emulsifiers with excellent emulsifying capacity exist in Camellia oleifera Abel. seeds. To explore the formation mechanism of these emulsions, a strongly emulsifiable component, a tea saponin-carbohydrate-protein complex (TCPC), is separated and purified by means of chromatography. Its physicochemical properties are characterized by the fourier transform infrared, thermogravimetric analysis, and scanning electron microscopy. The emulsifying properties of O/W emulsions prepared with TCPC (pH 7.0) are investigated systematically. The results show that the emulsions are remarkably stable over a wide range of pH values (5–11), ionic strength (0–200 mm NaCl), thermal treatment (60–90 °C; 30 min), and even after 14 days storage at room temperature (10–25 °C). Moreover, the rheological properties reveal that all determined emulsions show typical pseudoplastic fluid characteristics and shear-thinning flow behavior. However, the emulsions are unstable during freeze-thaw cycle. These results imply that TCPC may be one key emulsifiable compound during aqueous extraction of camellia oil. Practical Applications: Aqueous extraction is a promising technique for edible oil extraction from Camellia oleifera Abel. seeds because of its nutrition, safety and economy. However, the oil/water emulsions formed during the process of aqueous extraction of camellia oil, which makes oil hard to be separated. TCPC with excellent emulsifying activity and emulsion stability was separated and characterized, which could be regarded as a potential target to obtain free oil by frozen/thawed method. Thus, it could be contributing to the industrial application of aqueous extraction of camellia oil.     

超临界二氧化碳流体萃取油茶籽油及其GC／MS分析

采用环境友好的超临界二氧化碳流体萃取技术制备油茶籽油,考察了压力、时间、温度和二氧化碳流量等因素对茶籽油萃取率的影响,得到优化的工艺参数：当萃取压力30MPa、萃取温度35℃、CO2流量30L／h、萃取时间为3h时茶籽油萃取率可高达44．4％。根据中华人民共和国国家标准进行检测的结果表明：超临界二氧化碳流体萃取出的茶籽油,无需进一步精制即可达到国家食用植物油卫生标准GB／T2716—2005,而除含皂量、水分及挥发物外的指标均达到国家一级茶油标准GB11765—2003;GC／MS分析结果表明油茶籽油富含73．6％不饱和脂肪酸。实验结果表明：超临界二氧化碳流体技术萃取茶籽油具有操作简便、萃取率高、无溶剂残留、绿色环保等优点,萃取出的茶籽油具有较高的品质和良好的应用前景。     

Optimization of enzymatic pretreatment for n-hexane extraction of oil from Silybum marianum seeds using response surface methodology

An investigation on enzymatic pretreatment for n-hexane extraction of oil from the Silybum marianum seeds was conducted. The optimum combination of extraction parameters was obtained with the response surface methodology (RSM) at a four-variable and five-level central composite design (CCD). The optimum parameters of enzymatic pretreatment were as follows: enzyme concentration of 2.0% (w/w), temperature of 42.8 °C, reaction time of 5.6 h, and pH of 4.8. After enzymatic pretreatment, the oil was extracted by n-hexane for 1.5 h, and the oil yield on a dry basis was 45.70%, which well matched with the predicted value (45.86%). The results of the effects of the enzymatic pretreatment for n-hexane extraction of oil from the aspects of oil yield, microstructure and the fatty acid compositions showed that the enzymatic pretreatment had not affected on the fatty acid compositions, but could cause structure breakage of the S. marianum seeds and accelerate releasing extra oil, which increased the oil yield by 10.46% compared with n-hexane extraction for 1.5 h without enzymatic pretreatment, and confirmed the efficacy of enzymatic pretreatment for n-hexane extraction of oil from the S. marianum seeds.     

Optimization of the Aqueous Enzymatic Extraction of Oil from Iranian Wild Almond

The seeds of wild almond, Amygdalus scoparia, contain a relatively high quantity of oil. In the current study, aqueous enzymatic extraction of the oil from Iranian wild almond was investigated using a protease and a cellulase to assist the extraction process. The effects of temperature, incubation time and pH on the oil recovery were evaluated using Box?Behnken design from response surface methodology (RSM). A 77.3 % recovery was predicted for oil using aqueous enzymatic extraction procedure at the optimized conditions of RSM (pH 5.76; 50 °C/5 h) when both enzymes were used at 1.0 % level (v/w). In practice, when both enzymes were used, a maximum of 77.8 % oil recovery was achieved at pH 5; 50 °C/4 h. Fatty acid profile, refractive index and saponification value of the aqueous enzymatic extracted oil in the current study were similar to those of the oil extracted with hexane. However, acid value, unsaponifiable matter and p‐anisidine value were higher when compared to those with hexane extracted oil. Peroxide value of the aqueous enzymatic oil was lower than that of oil extracted by hexane. Aqueous enzymatic extraction can be suggested as an environmentally‐friendly method to obtain oil from wild almond.     

Enzymatic Production of Monoacylglycerols with Camellia Oil by the Glycerolysis Reaction

Three commercial immobilized lipases, Lipozyme RM IM, Lipozyme TL IM and Novozym 435, were screened for the production of monoacylglycerols (MAG) by glycerolysis of camellia oil in a solvent medium of tert-butyl alcohol. Novozym 435 showed the best performance and was selected to catalyze the glycerolysis reaction. Different reaction conditions for the batch reaction, substrate mole ratio, substrate concentration and temperature, were investigated. The optimal reaction conditions were determined as 6:1 mole ratio of glycerol to camellia oil at 40% (w/v) of substrate concentration in tert-butyl alcohol at a reaction temperature of 50 °C. Under these optimal conditions, the conversion rate of camellia oil was 98.7% (10 h), and the mixture of acylglycerols contained 82.0% of MAG. A packed-bed reactor (PBR) system with 4.5 g Novozym 435 was employed in continuous production. The resulting product mixture of acylglycerols contained 80.74% of MAG and was obtained at a flow rate of 0.25 mL/min of substrates. The long-term operation of the PBR system gave an average productivity of 0.698 kg MAG/(kg enzyme h) after 38 days of operation.     

Ethanol-Assisted Aqueous Enzymatic Extraction of Peony Seed Oil

An ethanol-assisted aqueous enzymatic extraction was performed for peony seed oil (content of 30%). This method included cooking pretreatment, pectinase hydrolysis, and aqueous ethanol extraction, and the corresponding variables in each step were investigated. The changes in viscosity and dextrose equivalent values of the reaction medium as a function of changing enzymatic hydrolysis time were compared to the oil yield. The microstructures of peony seeds were analyzed using confocal laser scanning microscopy to understand the process of oil release as a result of cooking and grinding. The highest oil yield of 92.06% was obtained when peony seeds were cooked in deionized water with a solid–liquid ratio of 1:5 (w/v) at 110°C for 1 hour, ground to 31.29 μm particle size, treated with 0.15% (w/w) pectinase (temperature 50°C, pH 4.5, time 1 hour), and then extracted with 30% (v/v) aqueous ethanol (temperature 60°C, pH 9.0, time 1 hour). After processing with pectinase followed by ethanol extraction, the residual oil content in water and sediment phase decreased to 5% and 3%, respectively. The quality of the oil obtained by ethanol-assisted aqueous enzymatic extraction was good, complying with the Chinese standard.     

Effect of rosehip extraction process on oil and defatted meal physicochemical properties

The physicochemical properties of oil from Rosa affinis rubiginosa seeds were analyzed after extraction by (i) organic solvent, (ii) cold pressing, and (iii) cold pressing assisted by enzymatic pretreatment using a mixture of the Novo-Nordisk A/S products Cellubrix (cellulase and hemicellulase activities) and Olivex (pectinase, cellulase, and hemicellulase activities). There were no significant differences in oil quality parameters, such as iodine value, refractive index, saponification value, unsaponifiable matter, and FA profile, when applying any of the three extraction processes. Although significant variations were observed in FFA content (acid value) and PV of the oil obtained by both of the cold-pressing oil extraction processes, these results were lower than the maximum value established from the Codex Alimentarius Commission. All-trans-retinoic acid content improved by 700% in rosehip oil obtained through cold pressing, with and without enzymatic pretreatment, in comparison with organic solvent extraction. This result is quite important for cosmetic oil because all-trans-retinoic acid is the main bioactive component responsible for the regenerative properties of this oil.     

Enzymatic Synthesis of an Isopropyl Ester by Alcoholysis of Camellia Oil

A camellia oil-based isopropyl ester (CO-IPE) was successfully synthesized by enzymatic alcoholysis with camellia oil (CO), and its physiochemical properties were analyzed. Three commercial immobilized lipases (Lipozyme RM IM, Lipozyme TL IM and Novozym 435) were screened, and Novozym 435 was the best one. The optimal reaction conditions were achieved at 240 U/g of Novozym 435 loading, a substrate molar ratio of 5:1 (isopropanol/CO), and 24 h of reaction time at 55 °C. Under the above conditions, the content of CO-IPE was obtained as 89.83%. Purity of CO-IPE further increased to be 96.95% after separation by rotary evaporation and molecular distillation. The viscosity of the synthesized CO-IPE showed itself to be about six times lower than that of CO, and the refractive index of the CO-IPE (1.449) was nearer to 1 in contrast to that of CO. It suggested that CO-IPE could be more intensively applied in the cosmetic industry.     

Antioxidant Activity and Total Polyphenols Content of Camellia Oil Extracted by Optimized Supercritical Carbon Dioxide

In this study, Camellia oil is co-extracted from Camellia oleifera seeds and green tea scraps by supercritical carbon dioxide (SC-CO₂), which is optimized on the extraction yield, ABTS-scavenging activity, and total polyphenols content (TPC) of oil by single-factor experiments combined with response surface methodology (RSM). The extraction temperature, pressure, dynamic time, carbon dioxide (CO₂) flow rate, and seed mass ratio were investigated with single-factor experiments. The results indicated the optimum CO₂ flow rate and dynamic extraction time were 15 L hour⁻¹ and 60 min (i.e., 2.382 kg CO₂/100 g sample). Furthermore, the complicated effects of extraction temperature (40–50 °C), pressure (20–30 MPa), and seed mass ratio (0.25–0.75) were optimized by RSM based on the Box–Behnken design (BBD). The models with high R-squared values were obtained and used to predict the optimum operating conditions of the process. Under the optimum operating conditions (i.e., temperature of 46 °C, pressure of 30 MPa, and seed mass ratio of 0.35), the extraction yield, ABTS-scavenging activity, and TPC of oil were 14.43 ± 0.17 g/100 g sample, 73.70 ± 0.34%, and 2.18 ± 0.05 mg GAE/g oil, which were in good agreement with the predicted values. In addition, the experiments indicated that the Camellia oil obtained was rich in polyphenols, resulting in better oxidation stability and antioxidant activity than the original oil.     

Enzymatic and Mechanical Extraction of Virgin Coconut Oil

The effect of different processing methods namely enzymatic method using crude protease extract (CPE) from overripe pineapple, microwave‐assisted extraction (MAE) and ultrasound‐assisted extraction (UAE) methods on the recovery yield of virgin coconut oil (VCO) is evaluated. The physicochemical properties of VCOs namely color, iodine value (IV), refractive index, saponification value, moisture content, free fatty acid, p‐anisidine value, lipid peroxidation, fatty acid composition, triacylglycerol (TAG) composition, melting and crystallization profile are compared. The total phenolic compounds and scavenging activity of the extracted VCOs are also examined. Results reveal that enzymatic approach exhibits the highest VCO yield (77.7% ± 0.38) at 50 °C for 2 h, followed by MAE (58.6%±0.07), control without enzyme (24.1%±0.19) and UAE (24.1%±0.12). The physicochemical properties of the VCOs extracted are found to conform to APCC standards established except IV. The antioxidant activity of VCO extracted with CPE shows no significant difference with MAE and UAE methods (p > 0.05). Lauric acid appears to be the most abundant fatty acid detected in all VCO samples. Similar exotherms and endotherms are observed in both melting and crystallization profiles with two distinct peaks exhibited. The TAG compositions of the extracted VCOs are mainly LaLaLa, LaLaM, CLaLa, CCLa, and LaMM (C = Capric acid; La = Lauric acid; M = Myristic acid). Practical Applications: The results obtained from this study indicate that VCO extraction using CPE from overripe pineapple is feasible. The enzymatic extraction protocol presented here would be useful for VCO production at industrial scale with a promising oil yield.     

Optimization of the Extraction of <Emphasis Type="Italic">Alpinia oxyphylla</Emphasis> Essence Oil in Supercritical Carbon Dioxide

The essence oil of the Alpinia oxyphylla seed has been used as a vasodilatatory and analgesic agent in pharmacology. The extraction of the essence oil in supercritical carbon dioxide (SC-CO₂) from Alpinia oxyphylla seeds was investigated. Small particles were obtained after breaking open, sieving, and drying from the Alpinia oxyphylla seeds. The small particles were placed in a 5-L extraction tank in a temperature-controlled system. The CO₂ flow rate of the system was set at 1 L/min in this study. Response surface methodology with a three-factor and three-level Box-Behnken experimental design was used to evaluate the effects of the reaction parameters such as extraction time (1, 2, 3 h), temperature (45, 55, 65 °C), and pressure (20, 30, 40 MPa), on the extraction yield of the essence oil from Alpinia oxyphylla seeds. The results indicate that the extraction pressure was the most important parameter affecting the yield of the essence oil. A model for the estimation of the yield was developed. Based on the analysis of ridge max, the optimal extraction conditions were established as an extraction time of 2.8 h, a temperature of 67.5 °C, and a pressure of 28.5 MPa, with an expected yield of 2.78%. Extraction of Alpinia oxyphylla essence oil in SC-CO₂ under these optimal conditions was conducted, and a yield of 2.77 ± 0.19% was obtained.     

Use of the Product from Low Pressure Extraction (Crambe Seed Oil and Methyl Acetate) for Synthesis of Methyl Esters and Triacetin Under Supercritical Conditions

Methyl esters (ME) and triacetin production from the supercritical interesterification of the product from low pressure extraction (crambe seed oil and methyl acetate) are evaluated. Reactions are conducted at 300–375 °C for different residence times, at 20 MPa, and under these conditions the thermal stability of triacetin is evaluated. The effect of the free fatty acid (FFA) concentration (in oil) is determined. An increase in temperature favors the formation of ME and triacetin at shorter reaction times. At 375 °C, after 15 min a drop in the ME yield is observed and triacetin is not detected. A reduction in the triacetin concentration (reaching ≈99%) is observed at 375 °C. High FFA concentration (in oil) initially provided higher product generation, however, after 15 min no influence is observed. The highest ME yield (≈60%) is obtained at 300 °C, along with 1.22 wt% triacetin and ≈5.0 wt% unreacted compounds. Practical Applications: This paper reports new experimental data on an integrated process for the production of methyl esters from low pressure extraction (crambe seeds and methyl acetate) and supercritical reaction of the extraction mixture. The technique used allows the removal of a high quantity of oil from good quality crambe seeds. The viability of applying the integrated process to obtain oils with a high content of free fatty acids is verified, promoting the obtainment of relatively simple methyl esters. The procedure does not require oil purification and solvent recovery prior to the reaction.     

The quality and volatile‐profile changes of camellia oil (Camellia oleifera Abel) following bleaching

Bleaching is a necessary step in the production of refined camellia oil (Camellia oleifera Abel) since crude oil has a dark brown color, due to pigments extracted from the seed coat during pressing, which is unacceptable to consumers. In order to understand the quality change and oxidative state of camellia oil in the bleaching step, measurements of various quality parameters, i.e. peroxide value (POV), free fatty acids (FFA), UV absorbance, and the volatile profiles of crude and bleached oils, were carried out. The results showed that FFA, K₂₇₀, and K₂₃₂ increased, whereas POV decreased, with increase of the activated earth dosage of 0–4% and of bleaching time from 0 to 40 min at 110 °C. As the amount of activated earth was increased from 0 to 4% with bleaching at 110 °C for 30 min, various classes of volatile compounds increased in concentration: aldehydes (23.7 µg/g), alcohols (13.2 µg/g), esters (8.0 µg/g), alkenes (2.0 µg/g) and ketones (1.9 µg/g). Likewise, when bleaching was carried out at 110 °C with 3% activated earth and the bleaching time varied between 0 and 40 min, the concentrations of volatile compounds also increased: aldehydes (27.7 µg/g), alcohols (18.2 µg/g), esters (7.3 µg/g), ketones (3.2 µg/g) and alkenes (0.6 µg/g). These findings indicate that hydroperoxides in the 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.     

乙醇提取油茶饼残油的研究

探讨了乙醇为溶剂热回流提取油茶饼中残油的方法。通过单因素实验及正交实验考察了乙醇体积分数、液料比、浸提温度、浸提时间及提取次数对油茶饼中残油收率的影响,确定了优化的提取条件为：乙醇体积分数95%、液料比10∶1（mL∶g）、浸提温度92℃、浸提时间3h、提取次数2次。在此优化条件下,油茶饼中平均残油收率达到残油含量的96.04%。研究结果表明,乙醇具有替代6号溶剂油提取油茶饼中残油的前景。     

Characterization and Benzo[a]pyrene Content Analysis of Camellia Seed Oil Extracted by a Novel Subcritical Fluid Extraction

A novel continuous subcritical n‐butane extraction technique for Camellia seed oil was explored. The fatty acid composition, physicochemical properties, and benzo[a]pyrene content of Camellia seed oil extracted using this subcritical technique were analyzed. Orthogonal experiment design (L₉(3⁴)) was adopted to optimize extraction conditions. At a temperature of 45 °C, a pressure of 0.5 MPa, a time of 50 min and a bulk density of 0.7 kg/L, an extraction yield of 99.12 ± 0.20 % was obtained. The major components of Camellia seed oil are oleic acid (73.12 ± 0.40 %), palmitic acid (10.38 ± 0.05 %), and linoleic acid (9.15 ± 0.03 %). Unsaturated fatty acids represent 83.78 ± 0.03 % of the total fatty acids present. Eight physicochemical indexes were assayed, namely, iodine value (83.00 ± 0.21 g I/100 g), saponification value (154.81 ± 2.00 mg KOH/g), freezing‐point (?8.00 ± 0.10 °C), unsaponifiable matter (5.00 ± 0.40 g/kg), smoke point (215.00 ± 1.00 °C), acid value (1.24 ± 0.03 mg KOH/g), refrigeration test (transparent, at 0 °C for 5.5 h), and refractive index (1.46 ± 0.06, at 25 °C). Benzo[a]pyrene was not detected in Camellia seed oil extracted by continuous subcritical n‐butane extraction. In comparison, the benzo[a]pyrene levels of crude Camellia seed oil extracted by hot press extraction and refined Camellia seed oil were measured at 26.55 ± 0.70 and 5.69 ± 0.04 μg/kg respectively.     

Aqueous-enzymatic extraction of plum kernel oil

An aqueous-enzymatic extraction process of plum kernel oil was investigated on a laboratory scale, varying several processing parameters, with main emphasis on the oil yield. Efficient recovery of oil was related to three operations: pretreatment, enzymatic reaction and separation of oil. Maximum oil yield of about 70% (estimated by the Soxhlet method) was obtained at an enzyme concentration of 0.5%, extraction temperature of 45°C, pH 4.5, treatment time of 1 h and dilution ratio of 1:4. The aqueous-enzymatic extraction did not have any determining effect on the fatty acid composition, tocopherol composition, iodine value and saponification value. The free fatty acid content was higher, while the phosphatide content and peroxide value were lower in the oil extracted by the aqueous-enzymatic process as compared to the Soxhlet extracted samples.     

油茶籽贮藏方法对油脂品质的影响

以小果油茶的油茶籽为研究对象,分析了7种贮藏方法对其及相应的油脂品质的影响。研究了油茶籽鲜果的含水率、出仁率,不同贮藏条件下的鲜果和风干籽的含油率,油脂的酸值、过氧化值、不皂化物含量。结果表明：12个月贮藏期后,不同的贮藏条件对油茶籽的含油率和油菜籽油不皂化物含量没有显著影响;对油菜籽油酸值和过氧化值的影响较为显著。综合考虑油茶籽油酸值、过氧化值两个指标的变化规律,干籽玻璃瓶包装冷冻（-18℃）贮藏法是最适宜贮藏油茶籽的方法,经12个月的贮藏,其油茶籽含油率和茶油不皂化物含量稳定,茶油的酸值和过氧化值均处于较低水平分别为1.46 mg/g和16.60 mmol/kg。     

Aqueous Enzymatic Extraction of Oil and Protein Hydrolysates from Roasted Peanut Seeds

To evaluate the effects of the roasting process on the extraction yield and oil quality, peanut seeds were roasted at different temperatures (130–220 °C) for 20 min prior to the aqueous extraction of both oil and protein hydrolysates with Alcalase 2.4 L. Roasting temperatures did not significantly affect the yields of free oil, whereas the temperature of 220 °C led to a reduced recovery of protein hydrolysates. The color and acid values of peanut oils did not change significantly with roasting temperatures. The enzyme-extracted oil with roasting at 190 °C had a relatively low peroxide value, a strong oxidative stability, and the best flavor score. Using the same seed-roasting temperature (190 °C), quality attributes such as color, acid and peroxide values, phosphorus content and oxidative stability of the enzyme-extracted oil were better than those of the oil obtained by an expeller. After the peanut seeds were roasted at 190 °C for 20 min, with a seeds-to-water ratio of 1:5, an enzyme concentration of 2%, and an incubation time of 3 h, the yields of free oil and protein hydrolysates were 78.6 and 80.1%, respectively. After demulsification of the residual emulsion by a freezing and thawing method, the total free oil yield increased to 86–90%.