The Joint Production Processing Technology Of Purple Sweet Potatoes’ Powder, Concentrated Juice And Anthocyanin

Purple sweet potato (Ipomoea batatas (L.)Lam), was also named black potato or purple-fleshed sweet potato. The color of flesh is from purple to dark purple. There are kinds of physiological effects rather than the basic compositions and functions of ordinary potatoes. The purple potato has being widely used as an important raw material in pabular, medical, chemical, light industrial and textile industry etc. With the valuing in healthcare and concerning about the food safety, because of the anthocyanins, DHEA, P-carotene and other function factors, Purple sweet potato is becoming more and more popular. The products of purple sweet potatoes are being welcomed all over the world, which also promote the rapid development of purple sweet potatoes industry.The joint production processing technology of purple sweet potatoes’powder and concentrated juice belongs to the major projects of agricultural science and technology in Shaanxi Province, which named as the higher production and efficiency in planting and processing technology of colorful sweet potatoes (Number:2012SNJC159NTF-H1). Based on the existing problems in joint production processing technology of purple sweet potatoes’powder and concentrated juice, and the detection method of anthocyanins, such as the high cost of production, low-usage of raw material and lacking of rapid and sensitive detection method etc. this paper had carried out the following works:(1) Qualification of the anthocyanins component in purple sweet potatoes with UPLC-MS/MS. (2) The Joint production processing technology of purple sweet potatoes’powder, concentrated juice and anthocyanins. (3) The quality analysis and nutritional evaluation of purple sweet potatoes’powder, concentrated juice and anthocyanins.The results of the researches are as follows:(1) A new UPLC-MS/MS qualification method of anthocyanins from Zishu No.1 and Nonglin 47 were set up using Cyanidin-3-glucoside as a standard. The analysis was carried out with chromatographic column of ACQUITY UPLC BEH C18 (2.1x50mm, 1.7μm), with the solvent of 6% formic acid and acetonitrile as the mobile phase, and the MS mode of the electrospray positive ion multiple reaction monitoring (MRM) mode. The results showed that the method was accurate, convenient and rapid with good repeatability.(2) The joint production processing technology of purple sweet potatoes’powder and concentrated juice was being set up, using Zishu No.1 from Hanzhong as raw materials. The purple potato residues A and purple potato juice were obtained after the process of washing, stripping and slicing, crushing, pulping and filtration. The purple sweet potato concentrated juice was obtained after the process of adding a-amylase and glucoamylase, gelatinization, liquefaction, saccharification and concentration. The anthocyanins concrete and the purple potato residues B were obtained by adding acidic ethanol into the purple potato residues A, after the process of extraction, filtration and concentration. The purple sweet potatoes’powder was obtained after the process of vacuum drying, smashing, sieving in purple potato residues B.The response surface method was employed to optimize the process parameters of starch gelatinization-liquefaction and purple sweet potato mash liquid preparation of the purple sweet potato. The process parameters were optimized and determined as follows: temperature 70℃, pH5.5, a-amylase content 1.20%, enzymolysis time 2h. The theoretical value of the total sugar content in starch solution was 27.39g/L under this condition; the optimized saccharification mash process parameters were determined as follows: temperature 60℃, pH4.5, glucoamylase dosage1%, saccharification time 2h. The theoretical value of saccharification mash total sugar content was 38.691 g/L under the conditions.The process parameters for the extraction of anthocyanins from purple sweet potato residues A were optimized by orthogonal experiment method. The extraction solvent was 75% alcohol with the pH4.0, the temperature 75 ℃. After the 1.5h extraction process, 1.5823 mg/g anthocyanins were obtained from purple sweet potatoes. The anthocyanins extracting solution’s color value is 1.132 after concentrated 100 timesThe residue B of purple sweet potato vacuum drying time is 36 hours at the temperature is 60℃. The powder’s water content is 5%.Using the joint production processing technology of purple sweet potatoes’powder and concentrated juice, we have got three products, the receiving rate of purple sweet potatoes’powder is 13.42%, the receiving rate of purple sweet potatoes’concentrated juice is 10%, the receiving rate of extract anthocyanins in purple sweet potato is 0.1466%.(3) A series of tests, based on the GB standard methods were carried out on purple sweet potato powder, concentrated juice, and the anthocyanins of purple sweet potato, which included the detection and analysis of sensory index, physicochemical indexes, hygienic index and nutritional ingredients. The results were showed as follows:the water content of purple sweet potato was 4.9%; ash content 10.1%; reducing sugar content 13.7%; total starch content 60.3%; the crude fiber content 7.9% and the protein content 1.9%. Soluble solids in purple potato concentrated juice were 30%; total acids (tartaric acid) 0.6%; Arsenic (As) 0.1mg/kg; 0.1mg/kg of lead (Pb); copper (Cu) 3.5 mg/kg. The anthocyanin of purple sweet potato’s color value is 1.132; total sugar 1.3%; protein 5%; ash content 6%.