Anti-Obesity Activity of α-AI Enriched Extracts From White Common Bean and Its Application In 3D Printing Foods

SHI Zhenxing. (2022). Anti-Obesity Activity of α-AI Enriched Extracts From White Common Bean and Its Application In 3D Printing Foods (PhD Dissertation in English). Gembloux AgroBio Tech, University, Gembloux Belgium, 151 pages, 11 tables, 22 figures.
Recent studies have shown that consumption of common bean (Phaseolus Vulgaris L.) foods contributes to the prevention and treatment of obesity, which mainly based on the starch blocker role of α-amylase inhibitor (α-AI) in common bean seeds. In this study, (1) the in vitro and in vivo inhibitory effects of α-amylase inhibitor enriched extracts (α-AIE) from white common bean on fat accumulation was studied, respectively; (2) the regulatory effects of α-AIE on the gut microbiota composition in high-fat diet-induced obese rats was investigated; (3) the 3D printing performance of common bean protein extracts (CBPE) which possess α-AI activity was evaluated.
Firstly, α-AIE was isolated from white common bean seeds (Cultivar Longquanjiuli) and its α-AI activity was determined to be 1027.1±154.2 (U·mg-1 protein). The effects of α-AIE on 3T3-L1 adipocytes differentiation were evaluated. Results of Oil Red O staining showed that a-AIE inhibited 3T3-L1 adipocytes differentiation. The quantitative results revealed that low dose (2 mg/mL) and high dose (4 mg/mL) of α-AIE reduced the lipid content in the mature adipocytes to 90.20% and 68.28%, respectively. Additionally, high dose of α-AIE showed significant suppression effects on the mRNA expression level and the protein expression level of (1) peroxisome proliferator-activated receptor γ (PPARγ), (2) CCAAT-enhancer-binding protein α (C/EBPα), and (3) fatty acid binding protein (ap2).
Secondly, the anti-obesity effect and gut microbiota modulation properties of α-AIE were verified in high-fat diet-induced obese rats. Intake of α-AIE significantly reduced the body weight, intra-abdominal fat accumulation and improved the serum lipid levels (p<0.05, R=0.94, 0.92 and 0.95), suggesting its inhibitory effects on fat accumulation in vivo. In addition, rats fed the α-AIE diet exhibited higher total short-chain fatty-acid (SCFA) concentrations (p<0.05, R=0.91) in their colonic contents. β-Diversity analysis, principal components analysis and a Venn diagram showed that α-AIE administration changed the gut microbiota composition. At the phylum level, the relative abundances of Firmicutes and Proteobacteria decreased and the relative abundances of Bacteroidetes and Akkermansia increased. Eighty-nine of operational taxonomic units (OTUs) significantly responding to high-fat diet and 30 OTUs significantly responding to α-AIE were identified. The OTUs enriched by α-AIE were mainly assigned to putative SCFA-producing bacteria, including Bacteriodes, Butyricoccus, Blautia and Eubacterium. Twenty-two of OTUs were found to be significantly correlated with obesity indexes.
Finally, CBPE powders with the α-AI activity of 961.30±29.43 (U·g-1 protein) were further smashed to different superfine grinds for 0, 6, 12 and 24 minutes. Then, the CBPE mixtures of Formula A (CBPE: 40%, alginate: 0.5% and gelatin: 6.0%) and Formula B (CBPE: 12%, xanthan: 0.05%, and agar: 3.5%) were confirmed with the addition of suitable additives, which can be applied in two types of printers (syringe extruder 3D printer and L3D kit 3D printer). Superfine grinding significantly (p<0.05, R=0.99) decreased the particle size of CBPE, and resulted in a reduction in the printability of the food-ink systems mainly through increasing (p<0.05, R=0.99) the adhesiveness of materials for the syringe-based 3D food printer, and increasing the swell powder (p<0.05, R=0.98) of materials for the gear-based 3D food printer. The decrease in the stability of printed products by the syringe-based 3D food printer was mainly due to the reduced water binding capacity (p<0.05, R=0.91) by superfine grinding. Besides, the syringe-based extrusion process was demonstrated to have no obvious effect (p>0.05, R=0.37) on the α-AI activity of CBPE. The 3D products of the L3D kit 3D printer with Formula B lost the α-AI activity but had very high stability.
All these results indicate that several dose of α-AIE from white common bean can inhibit the fat accumulation both in vitro and in vivo; Intake of α-AIE attenuated obesity and modulated gut microbiota composition in high-fat diet-induced obese rats. The addition of hydrophilic colloid improves the 3D printing performance of CBPE, but ultra-fine grinding degrades it. The results of our study should improve our knowledge of common bean α-IEA and its inhibitory effects on obesity as well as its valorisation and application in food additive manufacturing.