| Carrots with plentifully natural β-carotene play an important rule in medical treatment and health care. Used as the raw material, carrot was processed for the concentration carrot juice. Because of the enrichment of all the nutrition of carrot, especially high content of β-carotene, concentration carrot juice was increasingly applied to the fields of medicine and food and cosmetic. But β-carotene was located in the cell and hung together with cellulose, hemicellulose, pectin substance and xylogen. It can't be released from the carrot, so that the quality of concentration carrot juice was low. How to release furthest β-carotene from carrot was still an important technique problem harassing all the world in fruit juice process. In this study, the key technique to increase the content of β-carotene in concentration carrot juice was researched taking carrot as the raw material. The results showed that the extraction rate of β-carotene was over 74% and the content of β-carotene in concentration carrot juice (400Brix) above 80mg/100g. Simultaneo-usly the author expected this study could provide the theory and the data to product concentration carrot juice with high content of β-carotene. The main aspects are as follows: (1) Pre-treatment of raw material The technique of peeling carrot skins with the method of compound phosphate by means of orthogonal design L9(3~4) was studied in this paper. The results showed that the method of peeling with compound phosphate compared with other methods was optimal to peel off carrot skins. And the ratio of peeling reached 100%. Carrot color and lustre were good and its sarcocarp was not eroded. Simultaneously enzyme method and frost thawing method were referred to the pre-treatment of raw material in carrot juice process. In combination to and in comparison with current heating, the optimal condition of enzyme method was the first treatment of cellulase and then the next treatment of pectinase. The optimal condition of frost thawing was frost thawing three times and each time for two hours. On that condition, the extraction rate of β-carotene was increased by 140% for the enzyme treatment and increased by 73.62% for the frost thawing compared with control sample. (2) High-performance compound cell-wall-breaking technique Based on the pre-treatment of raw material, ultrasonic and microwave were applied for researching and establishing a suit of high-performance compound cell-wall-breaking technique adaptable to industrialization. The results showed that the method of "the first ultrasonic treatment, then frost thawing treatment, and then microwave treatment, and the last enzyme treatment"was the optimal way. In that way, the extraction rate of β-carotene was increased by 269% compared with control sample. (3) Kinetics of the carrot juice evaporating concentration process According to the fundamental principle kinetics, kinetics of the β-carotene losses was studied during the carrot juice evaporating concentration process. The kinetic model among the β-carotene losses, the content of solid materials and the temperature of the liquid materials during the evaporating concentration process was established. The kinetic model can be expressed as follows: kCdt? dC =; It can also be expressed by integral: C C0exp[0tkdt] =?∫In formula: k=k 0 exp(-Ea/RT),k 0=exp(3.8033Ea+11.4640); Ea=1.3892+2.2631lnBx;Bx=5.0672-0.198*t+0.37* ;k: the first order rate constant; k 0: the Arrhenius pre-exponential factor; Ea: the activation energy(Jmolt2-1); R: the gas constant, 8.314 Jmol ? 1; T: the absolute temperature(ok). If the temperature was changed, T in formula can be replaced by the equationof T=f(t). (4) Effect of the unit operation on the retention rate of β-carotene in process In the process of concentration carrot juice, a suit of scientific process engineering parameters was established. It was through the study on the influence to the retention rate of β-carotene caused by other unit operation in concentration carrot juice process.
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