Effects of Steaming on Sweet Potato Soluble Dietary Fiber: Content, Structure, and Lactobacillus Proliferation In Vitro

Abstract

The influence of steaming treatment on the soluble dietary fiber (SDF) of sweet potato was investigated. The SDF content increased from 2.21 to 4.04 g/100 g (in dry basis) during 20 min of steaming. The microcosmic morphology of the fractured cell wall indicated the release of SDF components during steaming. The SDF from fresh (SDF-F) and 20 min steamed (SDF-S) sweet potato was characterized. The neutral carbohydrates and uronic acid levels in SDF-S were significantly higher than SDF-F (59.31% versus 46.83%, and 25.36% versus 9.60%, respectively) (p < 0.05). The molecular weight of SDF-S was smaller than SDF-F (5.32 kDa versus 28.79 kDa). The probiotic property was evaluated by four Lactobacillus spp. fermentation in vitro with these SDF as carbon source, using inulin as the references. SDF-F showed the best proliferation effects on the four Lactobacillus spp. in terms of the OD600 and pH in cultures, and the highest production of propanoic acid and butyric acid after 24 h fermentation. SDF-S presented higher Lactobacillus proliferation effects, but slight lower propanoic acid and butyric acid production than inulin. It was concluded that 20 min of steaming released SDF with inferior probiotic properties, which might derive from the degraded pectin, cell wall components, and resistant dextrin.

Gastrointestinal Fermentable Polysaccharide Is Beneficial in Alleviating Loperamide-Induced Constipation in Mice

“…In our previous study, a soluble fiber composite (SDF-S) was extracted from steamed sweet potato, and it presented superior activity to inulin in promoting Lactobacillus spp. proliferation and fermentation in vitro [22]. In our recent preliminary experiment, it was also shown to alleviate loperamide-induced constipation in mice at a dose of 400 mg/(kg•bw•d) (as shown in Appendix A).…”

“…The preparation of SDF-S was conducted using the method that we previously reported [22]. Briefly, 20 min steamed sweet potato was freeze-dried, powdered, and extracted with hot water (40 • C) with the assistance of ultrasonic treatment.…”

“…According to our previous study [22], SDF-S is a low-Mw, resistant-dextrin-like DF and contains a variety of pectic substances (Appendix B). In the present study, two polysaccharide fractions, i.e., SSP-1 and SSP-2, were separated by using DEAE-FF ion-exchange chromatography, with water and 0.3 mol/L NaCl as the eluents, respectively (Figure 1), suggesting the neutral nature of SSP-1 and the acidic nature of SSP-2.…”

The influence of gentle processing of orange sweet potato on quality properties of purees

“…One of the most consumed crops in the world is represented by orange sweet potato (Ipomoea batatas L.). Consumed for the edible part, represented by the tuber, it remains an important source of carbohydrates and bioactive compounds (Zhang et al, 2023). Compared to potatoes (Solanum tuberosum L.), which have a glycemic index between 65 and 101, sweet potatoes have a glycemic index only between 63 and 66, which results in a less immediate impact on blood glucose levels.…”