| The quality characteristics of Shaddock varieties, the special products of Fujian,screening and mutation breeding of Naringinase producing strain, and function characteristics of Shaddock juice were studied systematically in this paper. Meanwhile on this basis, production technology of high-quality Shaddock juice and comprehensive utilization of Shaddock processing by-products were researched. The research results were as follow.(1)Study on quality characteristics of Shaddock variety in FujianThe study on nutrients quality of Shaddock showed that Vitamin C was the highest content of vitamin, and methionine was the first-limiting amino acid in fresh Shaddock.The study on processing quality shows that deep processing of Shaddock has unique advantages because of the lower total phenolic content and few polyphenol oxidase activity. It meaned enzymatic browning hardly occurred during processing. Shaddock flesh contained more pectin, which was a low-methoxyl pectin, that provided evidence for selecting the pectinase type for preparing juicing.The study on health-care quality showed that total flavonoids, polysaccharides, and SOD content varied among different varieties, which was significant for selecting optimal variety to exploit different types of Shaddock health-care food.(2)Study on screening and mutation breeding of Naringinase producing strainThe efficiency of screening and establishing the breeding model of Naringinase producing strain was improved by transparent plates method through color comparison of transparent layer and non-decomposed layer which had convenience for observation and measurement. One Naringinase producing strain, A-13,whose enzyme activity was up to 365.31 U /mL has been screened. Meanwhile, it was judged as Aspergillus niger by its morphological and cultural characteristics according to the .By NTG mutagenic treatment of original strain A-13 together with optimization of transparent circle method and screening and breeding with shake bottle, mutant A-13-62 was obtained, whose enzyme activity was up to 876.43 U /mL. The yield of enzyme of this mutant produced was 237% higher than that of original strain by shake flask culture method.The optimal fermentation medium and conditions of mutant A-13-62 has been confirmd with rhamnose as enzyme inducing agent. The optimal fermentation medium formula was as follow: 100g bean dregs(moisture 30%～40% ), 40g defatted bean cake flour, 0.2g rhamnose, 1g CaCl2, 1g ZnSO4, 5g MgSO4·7H2O, 1g K2HPO4, 1000mL distilled water. The optimum fermentation conditions: fermentation temperature 30℃, initial pH 5.0, fermented with 10%,50mL in 500mL triangle bottle,the enzyme activity of A-13-62 was 1017U/mL.The stability of high-yield strains A-13-62 by NTG mutagenic treatment was studied. Cultivated for several generations, A-13-62 reached a stable enzyme activity level of 1004U/mL, 272% higher than that of wild strains.(3)Study on critical Technology of Shaddock juice processingThe optimal process of Shaddock juice extraction with pectinase were put forward as follow: composite enzyme for hydrolysis (pectinaseX1 and GM with ratio of 1:1 ), hydrolysis time for 60 min, unchanged pH of raw juice, enzyme dosage 2000IU/kg, hydrolysis temperature 50℃.Under these conditions, the juice yield was improved by 22%,up to 48.9%.Fermentation broth of Naringinase was frozen and concentrated for enzyme activity 10000IU/mL as liquid enzyme,which was used to study the optimal conditions of debittering Shaddock juice by enzymatic method.And the results showed that: in the conditions of unchanged pH of raw juice, hydrolysis time for 60 min, enzymatic hydrolysis temperature 50℃, enzyme concentration 8000IU/kg, the hydrolysis was best and juice debittering ratio reached 46.25% with good flavor.The Shaddock juice drink had sweet-sour, dense tastes and peculiar flavor with the formula : Shaddock raw juice 20%,citric acid 0.06%,sugar 7.0%.(4)Study on the effect of Shaddock on reducing blood lipidsThe effect of Shaddock reducing blood lipid was studied with hyperlipemia rats model. Male SD rats were divided into six groups: normal control group, hyperlipemia model group, positive control group,and groups receiving 1.2mL/100g.bw low dose(100Bix), middle dose(200Bix) and high dose(300Bix) Shaddock juice respectively by gastric perfusion. Then detect the concentration of triglyceride(TG), total cholesterol (TCHO), high density lipoprotein(HDL-C),low density lipoprotein(LDL–C), apolipoprotein A/apolipoproteinB(ApoA/ApoB). The results showed that: significant decrease of serum lipids content and changes of lipoprotein composition were found in the hyperlipidemia rats fed with Shaddock juice for 4 weeks. Compared with model group significant decrease of TG was found in low dose(100Bix), middle dose(200Bix) and high dose(300Bix) groups (p<0.01) and also significant decrease of TCHO in high dose(300Bix) and middle dose(200Bix) groups(p<0.05或p<0.01) but HDL-C in high dose(300Bix), middle dose(200Bix) and low dose(100Bix)groups (p<0.01) and ApoA/ApoB in high dose(300Bix) and middle dose(200Bix) groups (p<0.05),were significantly increased. It showed that gastric infusion of Shaddock juice had therapeutic effects on the hyperlipidemia rats.(5)Study on the comprehensive utilization of Shaddock processing by-productsThe optimal processing condition of extracting pectin was studied by using pulp of fallen and thinning unripe fruit as raw material,with acid leaching and alcohol precipitation method. The extraction rate of pectin reached 3.15% at the optimal processing conditions: pH 0.5, extraction temperature 90℃, extraction time 80 min.The optimal processing condition of extracting total flavonoids from shaddock peel was studied with alcohol extraction method. The extraction rate of total flavonoids reached 0.607% at the optimal processing condition: extraction temperature 90℃, extraction time 2h, alcohol concentration 50%, dilution multiple 20.The optimal processing condition of extracting essential oil from shaddock seed was studied by supercritical carbon dioxide. The extraction rate reached 0.607% in the optimal processing condition: extraction pressure 35MPa, extraction temperature 40℃, CO2 flow rate 16L/h, extraction time 1h. Simultaneously the fatty acids analysis of essential oil from shaddock seed with gas chromtography showed that it contained 32.11% saturated fatty acid and 66.65% unsaturated fatty acid ,which were exploitable for edible oil resource.
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