The volatile flavor substances of 5 representative Mongolian cheese samples collected from different regions of Inner Mongolia were determined by headspace purge and trap (PT) coupled with triple quadrupole gas chromatography (QqQ-GC), and a flavor intensity evaluation model was constructed based on principal component analysis (PCA). The results showed that a total of 86 volatile substances were identified in Mongolian cheese, among which 24 were the main volatile substances. The flavor intensity evaluation model (F = 0.353 51F1 + 0.280 46F2 + 0.198 46F3 + 0.167 56F4) showed that the cumulative contribution rate of the first four principal components was 100.000%, which included ethyl caprylate, n-hexanol, ethyl decanoate, n-decanoic acid, acetic acid, and acetaldehyde, ect. They could reflect the original data accurately. In addition, the sensory evaluation results of the 5 cheese samples were consistent with the scores from the flavor intensity evaluation model, which indicated that the constructed model could effectively evaluate the flavor of Mongolian cheese, providing a new method for the evaluation of the flavor of Mongolian cheese.

Milk and purple sweet potato were used to produce purple potato supplemented cheese and the effect of the fermentation process on the change in dietary fiber content was investigated. Purple sweet potato, fermentation temperature and time were optimized using one-factor-at-a-time method and response surface methodology. The contents of nutrients and dietary fiber in cheese samples were measured by the national standard methods. The results indicated that the optimal process parameters were obtained as follows: 4% purple sweet potato flour, and fermentation at 42 ℃ for 8 h. The cheese prepared using the optimized conditions consisted of 19.79% protein, 15.62% fat and 46.75% moisture and contained 2.97 CFU/g of mold and its titratable acidity 78.03 °T, which met the national standards. In addition, the cheese had a dietary fiber content of 0.106 mg/100 g and its structure and texture was uniform. It was good in appearance with a light purple color and had the characteristic aroma of milk and the unique aroma and flavor of purple sweet potato.