| Citrus peel whose weight is30%-50%of Citrus, contained plenty of essential oil, pigment, pectin, flavonoids, limonin and dietary fiber and so on. Study on the co-production process of essential oil, pigment, pectin, flavonoids and dietary fiber from orange peel, in order to maximize utilization of orange peel.(1) The process conditions to extract essential oil from orange peel by steam distillation method was optimized. The optimum extracting condition was solution of NaCl concentration4.5%for60min with solid-liquid ratio1:12(g:mL), the yield of citrus essential oil was27μL·g-1.28compositions were identified by GC-MS analysis which was identical with the volatile oil extracted from citrus peel. The main composition was Limonene (91.99%), the rest which with higher content are1,4-Cyclohexadiene,1-methyl-4-(1-methylethyl)-(3.76%);1R-a-Pinene (0.47%);β-Pinene (1.25%) and1,6-Octadien-3-ol,3,7-dimethyl-(0.76%).The processing technology for preparing orange peel essence oil microcapsule with (3-cyclodextrin was investigated and optimized by Box-Behnken central composite test and response surface methodology. Afterwards, the stability of orange peel essential oil microcapsule was investigated by measuring its volatilization rate.The results showed that the encapsulating rate and the encapsulating yield of orange peels essence oil can reach65.66%and88.48%, respectively under condition of encapsulating temperature47℃, encapsulating time1.7h, and core/wall material ratio (orange peel essential oil/P-cyclodextrin)1:5.7. Besides, compared with the liquid orange peel essence oils, the volatilization rate of orange peel essence oil microcapsule reduced65.91%(20℃normal pressure blowing drying for24h). Results indicated that the microcapsule existed controlled-release capacity and high stability.(2) Taken orange peel (after essential oil extraction) as raw material, Box-Behnken central composite test and response surface methodology was used to optimize the extraction conditions of pigments from orange peels. And the stability of pigments from orange peel were studied. The optimum extracting condition were using95%aqueous ethanol as extraction solvent for extraction at75℃for120min with a material-to-liquid ratio of1:20(g:mL), the yield of pigments was22.4%; The pigments was unstable under light conditions, so it should be stored without light. Common food additives such as glucose and citric acid as well as oxidizer and reductant or some metal ions including Mg2+, K+, Na+, Mn2+and Ca2+had no adverse effect on the pigment. The pigment was sensitive under acidic condition, the color of pigment solution was deepened under alkaline condition.(3) The process conditions to extract pectin from orange peel (after pigments extraction) by acid extraction was optimized. Decolorization and the properties of pectin from orange peel were studied. Results indicated that the optimal conditions for acid extraction of pectin from orange peel were solution of pH1.5at95℃for120min with the solid-liquid ratio1:15(g:mL). The yield of pectin was12.66%under these optimal conditions. Macroporous resin of AB-8showed remarkable effect on the decolorization of pectin and the recovery rate of pectin was93.1%after decolorization. Main physical and chemical properties of the pectin:the pectin was pale yellow powder, pH2.94, ash content was4.52%, degree of esterification was71.63%and the content of galacturonic acid was76.05%. The results were in line with GB2484-2000standards.Box-Behnken central composite test and response surface methodology was used to optimize the production process of orange pectin preservative film. The optimum concentrations of pectin, glycerol, modified starch and polyvinyl alcohol are0.15%,3.57%,9.30%and0.30%, respectively. The orange pectin film treatment decrease the rot rate and weight loss by33.33%and146.63%of grape at the day of30under4℃,and increase the fruit firmness and TSS3.52%and10.84%, respectively.(4) Taken orange peel (after pectin extraction) as raw material, Box-Behnken central composite test and response surface methodology was used to optimize the extraction conditions of flavonoids from orange peels and AB-8macroreticular adsorptive resin was used to refining the flavonoids. The antioxidation activity of the product was evaluated.the optimum extracting solvent for flavonoid from orange peels is water, and solid to liquid ratio of1:38(g:mL) for an extraction duration of2h at99℃.Under these conditions, the yield of flavonoids was11.03mg·g-1; AB-8macroreticular adsorptive resin is a perfect adsorbent to refine the extracted flavonoids; It is proved that flavonoids from orange peels, especially the purified product, is a good natural antioxidant.(5) The process conditions to extract soluble dietary fibre from orange peel (after flavonoids extraction) by base extraction technology, ultrasonic-assisted extraction technology and enzyme extraction technology was optimized, respectively. Results indicated that the optimal conditions for base extraction of SDF from orange peel were solution of pH12.4at100℃for105min with the solid-liquid ratio1:30(g:mL). The yield of SDF was22.42%under these optimal conditions. The optimal conditions of ultrasonic-assisted extraction technology:the solid-liquid ratio1:30(g:mL), pH12.4, ultrasonic power300W and ultrasonic time15min, the yield of SDF was22.92%under these optimal conditions. The optimal conditions of enzyme extraction technology:after0.5%enzymatic hydrolysis for30min, base extraction90min at100℃, the yield of SDF was22.65%. Base extraction process for SDF was the optimal method by comprehensive comparison.Dietary fibre form orange peel were used for the production of chewing flakes. The effect of the addition the SDF, IDF, sweeteners, filler and milk powder on chewing tablet was studied. The results indicated that the chewing tablet with orange and milk fragrance tasty good when the additive concentration of dietary fiber (SDF:IDF=3:1),xylitol, denatured starch and yili whole milk powder was35%,19.7%,10.3%and10%, respectively. The chewing tablet contains total dietary fiber (43.23%), IDF(11.88%) of the SDF (18.66%), water (1.90%), protein (3.19%) and ash (4.80). |
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