| The international nutrient value assessment method was applied to general assessment of the protein value of potato protein meal (PPM) which provided by Zhuo Zi Long de Potato Starch Production Ltd. Com. in this study. The technics for extracting protein by the means of alkali-extracting and acid-precipitating were established for laboratory study. Adopting the laboratory technics course, a large amount of potato protein isolate was prepared for functional-properties exploration.The compositions of raw material were assayed and the results indicated that there were Crude protein 58.7%, Crude fat 2.1%, Crude fiber 11.7%, Ash 4.0%, Starch 11.9% and Water 5.3%, respectively. No detectable Solanine was present in potato protein and heavy metal was testified lower than National Safety. For example, plumbum: 0.11μg/g, arsenic: not detected, hydrargyrum: 0.03μg/g, chromium: 1.19μg/g, cadmium: 0.16μg/g, respectively. Consequently, this protein was safety.The international adopted nutrient value assessment method was applied to general assessment of the protein value of PPM: The results of the amino acid analysis showed that potato protein contained 19 amino acids. And the total essential amino acid in potato protein was high, making up of 47.9% of the total amino acids. We obtained the close degree from Fuzzy identification mode that potato protein was 0.91 and soybean protein isolate (SPI) was 0.84, respectively. So potato protein was higher than SPI. Amino acid analyses indicated the trytophan, sulfur amino acids (methionine+ cysteine) to be the first and second limiting amino acids in potato protein when compared to the recommended amino acid pattern for FAO/WHO (1973) mode. The amino acid score (AAS), chemical score (CS), essential amino acid index (EAAI), calculative biological value(C-BV), nutrition index (NI) and score of ratio coefficient of amino acid (SRCAA) of its protein were 88.0, 52.7, 87.8, 84.0, 36.9 and 76.9, respectively. Protein digestibility corrected amino acid score (PDCAAS) of potato protein compared to preschool children (2-5 years), school children (10-12 years) and adults were 0.75, 0.92 and 1.00, respectively.The nutritional values of protein isolated from potato were evaluated in growing rats. The protein quality of the potato protein was determined by comparing the apparent digestibility (AD), true protein digestibility (TD), biological value (BV) and net protein utilization (NPU). They were 90.01±0.28, 93.26±0.13, 78.61±3.74 and 73.31±3.40, respectively. Protein efficiency ratio (PER), corrected PER and net protein ratio (NPR) were 1.98±0.23, 2.4 and 2.52±0.38, respectively. There were no significant differences in potato protein and casein control group. The growth performance of potato protein was satisfactory and had no negative effects on the weight of their major organs. Together with their good protein quality as mentioned above, the potato protein c6uld be a potential alternative protein source for human nutrition.The technics for extracting protein by the means of alkali-extracting and acid-precipitating were established for laboratory study. The technics parameters were alkali-extracting pH 12.5, 40℃, 40 min, 1:40 of solid-liquid ratio and acid-precipitating pH 4.5 (25℃), leading to 56.21%, and 89.03% of protein content in product (by dry matter). It was determined that this protein mainly consisted of two subunits with the molecular weight of 59511 Dalton and 30761 Dalton, respectively.This paper explored the functional properties of the potato protein isolate, such as, solubility, water hydration capacity, emulsifying capacity, foaming ability and viscosity which were expected to be useful for the application of this protein.
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