Impact of steam cooking on the chemical profile of table-stock sweetpotatoes with different carotenoids content.

Sweetpotatoes are a great source of carotenoids, which are important for human health and have attracted increasing attention. This study examined the impact of the steaming method on the contents of carotenoids, starch, soluble sugar, volatile organic compounds, and pasting properties of nine table-stock sweetpotatoes with different carotenoids content (from 3.21 to 233.46 µg/g). After steaming, carotenoids content was significantly decreased, among which G79 and P32 had the highest levels of 88.20 µg/g and 94.27 µg/g, respectively. The starch content of G42 decreased the most (20 %) with the highest peak viscosity (1764.33 cP), while the amylose content of P32 increased the most (12.59 %) with the lowest peak viscosity (441.33 cP). The contents of total starch and amylose were significantly correlated with sensory evaluation. G79 presented the best sensory evaluation and a sweet, delicious, and soft texture. A total of 57 volatile organic compounds were detected, among which benzene, a few aldehydes, and terpenoids contributed to the aroma of steamed sweetpotatoes. These results provide a theoretical foundation for future sweetpotato processing.

Exploration of Raw Pigmented-Fleshed Sweet Potatoes Volatile Organic Compounds and the Precursors.

Sweet potato provides rich nutrients and bioactive substances for the human diet. In this study, the volatile organic compounds of five pigmented-fleshed sweet potato cultivars were determined, the characteristic aroma compounds were screened, and a correlation analysis was carried out with the aroma precursors. In total, 66 volatile organic compounds were identified. Terpenoids and aldehydes were the main volatile compounds, accounting for 59% and 17%, respectively. Fifteen compounds, including seven aldehydes, six terpenes, one furan, and phenol, were identified as key aromatic compounds for sweet potato using relative odor activity values (ROAVs) and contributed to flower, sweet, and fat flavors. The OR sample exhibited a significant presence of trans-ß-Ionone, while the Y sample showed high levels of benzaldehyde. Starch, soluble sugars, 20 amino acids, and 25 fatty acids were detected as volatile compounds precursors. Among them, total starch (57.2%), phenylalanine (126.82 ± 0.02 g/g), and fatty acids (6.45 µg/mg) were all most abundant in Y, and LY contained the most soluble sugar (14.65%). The results of the correlation analysis revealed the significant correlations were identified between seven carotenoids and trans-ß-Ionone, soluble sugar and nerol, two fatty acids and hexanal, phenylalanine and 10 fatty acids with benzaldehyde, respectively. In general, terpenoids and aldehydes were identified as the main key aromatic compounds in sweet potatoes, and carotenoids had more influence on the aroma of OR than other cultivars. Soluble sugars, amino acids, and fatty acids probably serve as important precursors for some key aroma compounds in sweet potatoes. These findings provide valuable insights for the formation of sweet potato aroma.

Effect of cooking methods on metabolites of deep purple-fleshed sweetpotato.

The effects of different cooking methods on purple-fleshed sweetpotato (PFSP) metabolites were systematically explored, containing the changes of starch, soluble sugar, volatile organic compounds and non-target metabolites after steaming, boiling and baking. Compared to raw samples, the steamed samples showed the greatest changes in starch (degraded from 53.01% to 39.5%) and soluble sugar content (increased from 11.82% to 29.08%), while the baked samples showed insignificant changes in starch (51.06%). In total, 64 volatile organic compounds were identified in PFSP, with aldehydes decreasing and terpenes increasing after cooking. However, most of them were low in content and contributed weak aroma for PFSP. More importantly, 871 non-volatile metabolites were detected in PFSP, and 83.5% of which were well-preserved after cooking, while most of the changes were concentrated in phenylpropanoids, amino acids and carbohydrates. This study enriches the understanding of quality changes after PFSP cooking and helps consumers choose the right cooking method.