Comparative studies on physicochemical properties of three potato varieties different in RS2 and RS3 contents.

BACKGROUND: At present, increasing importance has been attracted to healthy food enriched in resistant starch (RS), which has great benefits in health-promoting. Raw potato has rich RS2, whereas most RS2 may become digestible after gelatinization, resulting in few RS being left in processed potato. Breeding potatoes with high RS2 or RS3 or both can meet the demand for various healthy potato products. RESULTS: There were apparent discrepancies among three potatoes with contrast RS2 and RS3 content in thermal properties, viscosity and digestibility. ZS-5 had the highest RS2 with 50.17% but the lowest RS3 with 3.31%. Meanwhile, ZS-5 had the largest starch granule, the highest proportion of B3, viscosity and hardness, and the highest digestibility. DN303 with the highest content of RS3 (5.08%) had the lowest hardness and fracturability. MG56-42 with both higher RS2 and RS3 content showed the highest resistance to digestion and moderate hardness and fracturability. CONCLUSION: The present study enriches the potential resources and provides a reliable scientific basis for high RS potatoes breeding. The various features of different potatoes make it possible to screen potatoes according to different demands. © 2023 Society of Chemical Industry.

Retaining a large amount of resistant starch in cooked potato through microwave heating after freeze-drying.

Resistant starch (RS) is beneficial for humans, especially for the diabetes. Raw potato had a great deal of RS, while most of which become digestible after gelatinization. Thus, few RS will be retained in potatoes after regular cooking. To preserve RS in cooked potatoes as much as possible, microwave heating before (MFD) and after freeze-drying (FDM) were conducted with three different potatoes. After MFD, the RS content in potatoes was lower than 7% and the RDS content was higher than 45% for three potatoes. However, RS in potatoes treated with FDM was still as high as 40%, similar to that in the raw potatoes. Meantime, FDM caused less browning, produced a certain level of pyrazines, benzeneacetaldehyde and other flavor compounds, endowing cooked potatoes special baked flavor. Freeze-drying before microwave heating is a valuable way to reserve RS in cooked potatoes, which could also be used to reserve high RS content in crisp, chips, and other processed potatoes.