In 2014, potato production in China amounted to 96 million tons, which was the highest in the world. As one of the most important nutritional foods in the world, potato is rich in starch, dietary fiber, vitamins, minerals, etc. Potatoes stand barren environment, drought, saline, and alkaline environment, and cold weather, with a short growing season. These features make them the best rain-fed crops suitable for production even when the annual rainfall is below 400 mm. In 2013, the Chinese Ministry of Agriculture suggested a potato staple food strategy using potatoes to make Chinese traditional staple foods such as steamed bread, noodles, etc. Our research group carried out a study on processing technology of potato staple food, especially fermented staple food. Some new processing technologies of potato staple food have been investigated and developed. The aim of this paper is to give an overview of the possible effects of adding potato flour in the dough and of the microstructure characteristics, technological parameters, total polyphenol content, and antioxidant activity of staple foods. We also systematically describe the processing technology of potato staple foods, which may be of great importance in promoting further expansion of the potato-processing industry and increasing the economic benefit of the companies.
We previously reported that sensitivity to Congo Red (CR) or Lysing Enzymes (LE) is affected by the loss of cell-wall α-1,3-glucan (AG) in Aspergillus nidulans. We found that the amount of CR adsorbed to AG was significantly less than the amount adsorbed to β-1,3-glucan (BG) or chitin, suggesting that loss of cell-wall AG would increase exposure of BG on the cell surface, and thereby increase the sensitivity to CR. Generally, fungal BGs are known as biological response modifiers because of their recognition by Dectin-1 receptors in human immune systems. Therefore, isolation of AG-deficient mutants in Aspergillus oryzae has been used in the Japanese fermentation industry to create strains with increased ability to promote immune responses. Here, we aimed to isolate AG-deficient strains by mutagenizing A. oryzae conidia with chemical mutagens. Based on the increased sensitivity to CR in AG-deficient strains of A. nidulans and A. oryzae, we established a screening method for isolation of AG-deficient strains. Several candidate AG-deficient mutants of A. oryzae were isolated using the screening method; these strains showed increased sensitivity to CR and/or LE. Cytokine production was increased in the dendritic cells co-incubated with germinated conidia of the AG-deficient mutants. Furthermore, according to a Dectin-1 NFAT (nuclear factor of activator T cells)-GFP (green fluorescent protein) reporter assay, Dectin-1 response levels in the AG-deficient mutants were higher than those in wild-type A. oryzae. These results suggest that we successfully isolated AG-deficient mutants of A. oryzae with immunostimulatory effects.
Potatoes are generally regarded as high glycemic index (GI) foods. Resistant starch (RS) comprises the starch fraction that is not absorbed in the small intestine, thus controlling the glucose level and improving the intestinal environment. In this study, an analysis of the formation of RS of potato starch samples under different acetic acid-thermal treatment conditions was conducted. Additionally, the relationship between the rates of starch digestion, estimated GI (eGI), and the RS content was evaluated by employing in vitro enzymatic models. Compared with control samples, the RS content in the cold-stored samples after acid-boiling was higher, whereas that of samples after heating at 120 °C with acetic acid was decreased. The eGI was negatively correlated with the RS content in potatoes. Cold store after acid-boiling was effective in increasing the RS content. Furthermore, low eGI values may have resulted from higher levels of RS in potatoes.