Preparation and characterization of konjac glucomannan and gum arabic composite gel

Author(s):  
Zhenyu Li ◽  
Ling Zhang ◽  
Chunling Mao ◽  
Zhiming Song ◽  
Xinxin Li ◽  
...  
Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1460
Author(s):  
Jiaxin Chen ◽  
Jinhai Zhao ◽  
Xin Li ◽  
Qian Liu ◽  
Baohua Kong

The effect of the partial replacement of pork back-fat with a cube fat substitute (CFS) fabricated from konjac glucomannan and carrageenan on the physicochemical and sensory characteristics of Harbin dry sausages during 7 days of fermentation was investigated. There were the following five treatments: control (100% back-fat), FS1 (80% back-fat, 20% CFS), FS2 (60% back-fat, 40% CFS), FS3 (40% back-fat, 60% CFS) and FS4 (20% back-fat, 80% CFS). The results showed no significant differences (p > 0.05) in the physicochemical and sensory characteristics among the control, FS1 and FS2 treatments. However, higher replacement levels (60% and 80%) rendered higher degrees of change in the characteristics of the sausages, lowering the moisture content and aw and increasing the pH, hardness, chewiness and atypical appearance at the end of fermentation. Moreover, electronic nose analysis and hierarchical cluster analysis demonstrated that the FS3 and FS4 treatments destroyed the characteristic quality of the sausage. Overall, our results indicated that, to ensure the traditional characteristics of Harbin dry sausages, the upper limit of the fat replacement level with CFS should be set at 40%.


Author(s):  
Yuki Sasaki ◽  
Ayako Horigome ◽  
Toshitaka Odamaki ◽  
Jin-Zhong Xiao ◽  
Akihiro Ishiwata ◽  
...  

Gum arabic arabinogalactan (AG) protein (AGP) is a unique dietary fiber that is degraded and assimilated by only specific strains of Bifidobacterium longum subsp. longum. Here, we identified a novel 3-O-α-d-galactosyl-α-l-arabinofuranosidase (GAfase) from B. longum JCM7052, and classified it into the glycoside hydrolase family 39 (GH39). GAfase released α-d-Galp-(1→3)-l-Ara and β-l-Arap-(1→3)-l-Ara from gum arabic AGP and β-l-Arap-(1→3)-l-Ara from larch AGP, and the α-d-Galp-(1→3)-l-Ara release activity was found to be 594-fold higher than that of β-l-Arap-(1→3)-l-Ara. The GAfase gene was part of a gene cluster that included genes encoding a GH36 α-galactosidase candidate and ABC transporters for the assimilation of the released α-d-Galp-(1→3)-l-Ara in B. longum. Notably, when α-d-Galp-(1→3)-l-Ara was removed from gum arabic AGP, it was assimilated by both B. longum JCM7052 and the non-assimilative B. longum JCM1217, suggesting that the removal of α-d-Galp-(1→3)-l-Ara from gum arabic AGP by GAfase permitted the cooperative action with type-II AG degradative enzymes in B. longum. The present study provides new insight into the mechanism of gum arabic AGP degradation in B. longum. IMPORTANCE Bifidobacteria harbor numerous carbohydrate-active enzymes that degrade several dietary fibers in the gastrointestinal tract. B. longum JCM7052 is known to exhibit the ability to assimilate gum arabic AGP, but the key enzyme involved in the degradation of gum arabic AGP remains unidentified. Here, we cloned and characterized a GH39 3-O-α-d-galactosyl-α-l-arabinofuranosidase (GAfase) from B. longum JCM7052. The enzyme was responsible for the release of α-d-Galp-(1→3)-l-Ara and β-l-Arap-(1→3)-l-Ara from gum arabic AGP. The presence of a gene cluster including the GAfase gene is specifically observed in gum arabic AGP assimilative strains. However, GAfase-carrier strains may affect GAfase-noncarrier strains that express other type-II AG degradative enzymes. These findings provide insights into the bifidogenic effect of gum arabic AGP.


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