Preparation And Characteristics Of Coconut Oil-based Nanoemulsion

Food and beverage products containing functional ingredients are more conducive to human health.The application of functional oils and fats in nanoemulsions has broad prospects.This topic used temperature gradient field to separate virgin coconut oil(VCO)and got fractionated coconut oil.A new type of functional oil and fat phase is formed with green tea seed oil as a base oil to prepare a coconut oil-based nanoemulsion.The effects of several emulsifiers on the properties of coconut oil-based nanoemulsions were studied,and the process of preparing coconut oil-based nanoemulsions by response-to-ultrasonic method was optimized,and the properties of the optimized nanoemulsions were evaluated to prepare safe,Coconut oil-based nanoemulsion with high nutritional value.The results of the study will lay a theoretical foundation for the development and production of natural emulsifier-stabilized nanoemulsion systems containing functional oils and fats,and provide high-quality raw materials for the production and processing of the food industry.The main research contents are as follows:(1)Using VCO as raw material,fractionated coconut oil is prepared by temperature gradient field fractionation method,heating temperature is 35 ℃,condensation temperature is 10 ℃,ultrasonic power is 60 W,and crystallization time is 2 h.The physical and chemical indexes of VCO and the changes of fatty acid composition after fractionation were studied.The results showed that the temperature gradient field fractionation will not affect the quality index of the oil phase.The content of medium and short-chain fatty acids obtained in fractionated coconut oil is obvious compared to VCO Increase,the proportion increased from 12.87 % to 61.44 %,making it easier to be quickly absorbed and not easy to solidify,it is a potential new functional grease.(2)In order to select a suitable emulsifier for the preparation of coconut oil-based nanoemulsions,the effects of different types of emulsifiers on the surface tension and formation of nanoemulsions were studied.Whey protein isolate,soy lecithin,tea saponin and Tween 80 were selected.As an emulsifier,a nanoemulsion is prepared using an ultrasonic method.The measurement results of the change of surface tension with concentration showed that the surface tension of whey protein isolate-stabilized nanoemulsion was unstable with concentration and was always large;when soybean lecithin,tea saponin and Tween 80 were used as emulsifiers to stabilize coconut oilbased nanoemulsion It can be adsorbed to the water-oil interface faster and reduce the surface tension,which may provide better stability.The effect of emulsifier concentration on the formation shows that as the emulsifier concentration increases to a certain extent,the average particle size of several natural emulsifier-stabilized nanoemulsions can reach a small level and remain stable.The Zeta-potential value The measurement results show that the stability of the nanoemulsion is good.Among them,soybean lecithin can reduce the average particle size of the nanoemulsion to 203.36 ? 2.22 nm,and the minimum average particle size of the nanoemulsion stabilized by whey protein isolate is 267.67 ? 3.06 nm.The minimum particle size of the tea saponinstabilized nanoemulsion is 130.83 ? 1.11 nm,which is similar to the size of the Tween 80-stabilized nanoemulsion 126.26 ? 0.7 nm,and it exhibits the best emulsification performance among several natural emulsifiers.(3)The type of emulsifier has a great influence on the stability of the nanoemulsion.The evaluation results of the stability of the coconut oil-based nanoemulsion stabilized by several emulsifiers under different environmental pressures by measuring the average particle size and Zeta-potential show that: whey separation The stability of protein-stabilized nanoemulsion is less affected by ionic strength,but it deteriorates when the temperature is in the range of p H 3 to 5 or the heat treatment temperature is higher than 60 ° C.Soy lecithin-stabilized nanoemulsion shows instability after p H 3 ～ 5 and ionic strength greater than 0.1mol / L,but it is less affected by heat treatment.The tea saponin and Tween 80 stabilized nanoemulsions are well tolerant to environmental pressure and can maintain good stability within the studied environmental pressure range.(4)The long-term storage stability of coconut oil-based nanoemulsions stabilized by several emulsifiers at different temperatures was studied: the storage of several natural emulsifier-stabilized coconut oil-based nanoemulsions at 5 ° C and 27 ° C for 45 Days Both are able to maintain a small average particle size and a stable Zetapotential,showing good stability.During the long-term storage at 50 ℃,the whey protein isolate and soybean lecithin stabilized nanoemulsion showed instability,the tea saponin stabilized nanoemulsion could remain stable,and the Tween 80 stabilized nanoemulsion was only available at 45 Day that is instability.(5)The in vitro digestion characteristics of several coconut oil-based nanoemulsions stabilized by emulsifiers were studied: Whey protein isolate-stabilized coconut oil-based nanoemulsions have poor tolerance to gastric juices,and several other types of new functional oils can Phase transport to the small intestine.Several nanoemulsions greatly improved the bioavailability of crude emulsion 41.8?0.13 %,in order: whey protein isolate 68.03 ? 0.60 %,soybean lecithin 87 ? 1.08 %,tea saponin 98.6 ? 0.6 %,Tween 80 92.76 ? 0.25 %,the performance of the other three nanoemulsions to improve bioavailability is better than the coconut oil-based nanoemulsion stabilized by whey protein isolate.(6)In order to obtain coconut oil-based nanoemulsions enriched in fractionated coconut oil and green tea seed oil,soybean lecithin was used as an emulsifier,and the main factors including emulsifier content,ultrasonic power,ultrasonic time,and their interaction on ultrasonically prepared nanoemulsions were studied.With the influence of average particle size,the preparation conditions were optimized by response surface method and the stability and bioavailability of the optimized nanoemulsion were evaluated.The results show that the optimal process parameters are: emulsifier content 2.2 %,ultrasonic power 351 W,ultrasonic time 12 min,the average particle size of the nanoemulsion obtained is 183 ? 1.58 nm.The prepared nanoemulsion has good p H,heat-treatment,and storage stability,and the bioavailability of the mixed oil phase of coconut oil and green tea seed oil is 93.88 ? 1.08 %.