| Kiwifruit is one of the world's largest consumption of fruit.Bacause of its high nutritional value and significant health care function like antioxidation and antitumor activity,it was favored by a vast number of consumers.Our country is rich in kiwi resources,especially in Shaanxi province.However,kiwi is a climacteric fruit,which are easily rotten after picking.Accordingly,as a kind of deep processed product of kiwi fruit,kiwi fruit compound powder has a broad prospect of development due to its advantages of portable storage,nutrition and health function.In this paper,the quality character and milling characteristics of seven varieties of kiwifruit from Shannxi were studied.After that,the effect of broccoli,apple and mung bean on the kiwi powder were evaluated and the formula of kiwifruit compound powder was obtained.Finally,the processing technology of kiwifruit compound powder was studied.The result is as follows.(1)Seven varieties of kiwifruit were conduct the comparison of the texture,color and nutritional component by the different means and the result indicated that there were great differences in texture(cohesiveness,chewiness),color(L*?a*?b*)and nutrition among the seven species.The vitamin C was in the range of 73.63~192.93mg/100 g,hardness was in the range of 76.68~161.01 g,chewiness was in the range of 6.56~38.28 g,cohesiveness was in the range 14.65~29.05 cohesiong,and the hardness,chewiness and cohesiveness of Cuixiang kiwifruit were all the highest.The range of calcium element content of seven varieties of kiwifruit was 313.30~512.40?g/g,the range of iron element was between 12.93~53.90?g/g,while zinc element was in the range of 2.15~4.90 mg/kg,in which the calcium element content of Cuixiang,the iron element content of Huayou kiwifruit,and the zinc element content of Hongyang kiwifruit were the highest,respectively.The vitamin C content content of Huayou kiwifruit was the highest,which was 192mg/100 g.The scavenging capability of DPPH· and reducing capability of Huayou kiwi were the highest,which were 854?mol/100 g Trolox and 6455 g Vc/100 g.Kiwifruit powder was prepared from seven varieties of kiwifruit,and its properties were studied.The result showed that there were great differences in milling rate,hygroscopicity,emulsifying property antioxidant activity among the seven species.The milling rate of Hongyang kiwi was the highest,which was 23.67%.The highest scavenging capability of DPPH· and reducing ability of kiwifruit powder attributed to Huayou and Hongyang kiwifruit powder,which were 1412?mol/100 g Trolox and 2314 g Vc/100 g,respectively.(2)The thermal degradation test showed that the thermal reaction of chlorophyll in kiwifruit pulp accorded with the first-order kinetic equation,and the reaction rate constant changed with the temperature and pH.RVA and Light microscope were used to observe the mung bean pulp and the result showed that mung bean was helpful to improve the stability and anti caking of kiwifruit powder when the water ratio was 1:6.The result of color analysis and sensory evaluation showed that broccoli and apple helped to make kiwi powder a natural green when their water ratio were all 1:2.The effect of the amount of broccoli,apple and mung bean on the sensory quality,sugar acid ratio,vitamin C,powder properties(hygroscopicity,emulsifying property,water holding capacity)and antioxidant activity of kiwifruit powder were examined.The parameters of addition were broccoli 16%~24%,apple 8%~16%,mung bean 8%~16%,which can obtain kiwifruit powder with the best sensory effects.The parameters of addition were broccoli 32%~40%,apple less than 8%,mung bean 8%~16%,which can obtain kiwifruit powder with the best humidity resistance.The parameters of addition were broccoli 24%~32%,apple and mung bean less than 8%,which can obtain kiwifruit powder with the best antioxidative activities.(3)D-optimization design was used to design and optimize the the formulation of kiwifruit compound powder in accordance with sensory value and the better formulation of kiwifruit compound powder was obtained.Five indexes of formula optimization were obtained by means of principal component analysis,cluster analysis from sixteen hysical and chemical indexes like color value,powder properties and antioxidant activity,while a mathematical model for optimizing the formula of kiwifruit compound powder was established by means of and mathematical statistics,which was Y=0.3333×a*value+0.3004×DPPH·+0.3258×Vc+0.1982×chlorophyll +0.0504× reducing sugar.The results of D-optimal test and mathematical statistics were verified,which indicated that two methods were consistent and the formulation of kiwifruit compound powder was obtained: the optimum combinations of kiwifruit,broccoli,apple and mung bean were70.20%,12.00%,8.10% and 9.70%,respectively.(4)The processing technology of kiwifruit compound powder was investigated.The result indicated that in the nine processings of pretreatment of raw plup,the kiwifruit compound powder after 400 MPa ultrahigh-pressure pretreatment had the high vitamin C content,the high scavenging capability of DPPH· and ·O2-as well as reducing ability,which were 1902.32mg/100 g,1678?mol/100 g Trolox,47.23% and 2101 g Vc/100 g,respectively.The effect of four drying methods on kiwifruit compound powder were studied.The result showed that the compound powder of vacuum and infrared drying had the highest preservation rate of vitamin C,total phenols and chlorophyll,which were 87.87%,82.75% and 93.62%,respectively,while the dissolution time,water holding capacity and emulsifying property of vacuum and infrared drying were the best.Isothermal absorption and anti caking test results showed that when the relative humidity at 80%~90%,the hygroscopicity of kiwifruit composite powder increased sharply.When the temperature was 40 degrees centigrade,caking strength of kiwifruit compound powder increased sharply along with the increase of humidity,the which caking strength of kiwifruit compound powder at 80% RH was 12.5 times than at 60% RH. |
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