Abstract: In order to study the changes of the nutrients in red jujubes after being infected with black spot disease, we analyzed 14 infected and healthy jujube samples collected from 7 jujube orchards in South Xinjiang for 31 nutritional components (sugars, amino acids, total acid, total sugar, reducing sugars, proteins and mineral elements) and four main toxic metabolites (Alternaria toxins). Results showed that the contents of 7 mineral elements were decreased significantly in infected jujubes as compared with healthy ones. Among the 17 amino acids detected, the contents of 8 bitter amino acids (Val, Iie, Leu, Tyr, Phe, His, Lys, and Arg) were all increased while one sweet amino acid, Pro, was significantly decreased. The contents of fructose, sucrose, reducing sugar, total sugar, total acid and water-soluble protein were significantly reduced, whereas glucose content was increased. Tenuazonic acid (TeA), the most toxic among the four metabolites, was detected in all samples, at a significantly lower level in health jujubes than in infected ones. In addition, by partial least squares discriminant analysis we found that alternariol (AOH), aspartic acid, methionine, TeA and lysine could act as main indicators to distinguish between healthy and infected jujubes. This research provides novel ideas for future metabolomics research of red jujubes infected with black spot disease.

Key words: black spot, red jujubes, nutritional components, Alternaria toxins, metabonomics