scholarly journals Bacterial and Fungal Microbiota of Guinea Grass Silage Shows Various Levels of Acetic Acid Fermentation

Fermentation ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 10
Author(s):  
Jianjian Hou ◽  
Naoki Nishino

This study aimed to gain insights into the bacterial and fungal microbiota associated with the acetic acid fermentation of tropical grass silage. Direct-cut (DC, 170 g dry matter [DM]/kg) and wilted (WT, 323 g DM/kg) guinea grass were stored in a laboratory silo at moderate (25 °C) and high (40 °C) temperatures. Bacterial and fungal microbiota were assessed at 3 days, 1 month, and 2 months after ensiling. Lactic acid was the primary fermentation product during the initial ensiling period, and a high Lactococcus abundance (19.7–39.7%) was found in DC silage. After two months, the lactic acid content was reduced to a negligible level, and large amounts of acetic acid, butyric acid, and ethanol were found in the DC silage stored at 25 °C. The lactic acid reduction and acetic acid increase were suppressed in the DC silage stored at 40 °C. Increased abundances of Lactobacillus, Clostridium, and Wallemia, as well as decreased abundances of Saitozyma, Papiliotrema, and Sporobolomyces were observed in DC silages from day three to the end of the 2 month period. Wilting suppressed acid production, and lactic and acetic acids were found at similar levels in WT silages, regardless of the temperature and storage period. The abundance of Lactobacillus (1.72–8.64%) was lower in WT than in DC silages. The unclassified Enterobacteriaceae were the most prevalent bacteria in DC (38.1–64.9%) and WT (50.9–76.3%) silages, and their abundance was negatively related to the acetic acid content. Network analysis indicated that Lactobacillus was involved in enhanced acetic acid fermentation in guinea grass silage.

Foods ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 181 ◽  
Author(s):  
Rui Li ◽  
Qi Ding ◽  
Xin-Huai Zhao

The impact of milk fortification on the microbiological and physicochemical properties of a set-type skimmed yoghurt using three commercial soluble prebiotics (inulin, iso-malto-oligosaccharides, and xylo-oligosaccharides) at either 3 or 5 g/kg was assessed. The three prebiotics had an insignificant impact on yoghurt fermentation because all yoghurt samples had similar titratable acidity and similar pH values after their lactic acid fermentation. Regarding the control yoghurt samples without prebiotics usage, the prebiotics-fortified yoghurt samples showed no difference in their main chemical compositions, hardness, syneresis extent, and apparent viscosity (p > 0.05), but had a slightly higher lactic acid content and a viable quantity of starter strains. All yoghurt samples had the same acetic acid content, while propionic and butyric acids were not produced. Yoghurt storage at 4 °C for 21 day gave these yoghurt samples decreased pH values and a viable quantity of starter strains (especially Lactobacillus delbrueckii subsp. bulgaricus) and unchanged acetic acid; however, it increased lactic acid contents. Overall, prebiotics fortification up to 5 g/kg had a completely insignificant impact on the fermentation and quality attributes of yoghurt samples but could possibly improve the health of consumers due to higher dietary fibers and starter strain populations.


Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 768
Author(s):  
Christos Bontsidis ◽  
Athanasios Mallouchos ◽  
Antonia Terpou ◽  
Anastasios Nikolaou ◽  
Georgia Batra ◽  
...  

On the frame of this research survey, a novel potentially probiotic strain (Lactobacillus paracasei SP5) recently isolated from kefir grains was evaluated for chokeberry juice fermentation. Chokeberry juice was retrieved from the variety Aronia melanocarpa, a plant known to provide small, dark berries and to be one of the richest sources of antioxidants. The juice was subsequently fermented inoculating L. paracasei SP5 for 48 h at 30 °C. The fermented juices were left at 4 °C and tested regarding microbiological and physicochemical characteristics for 4 weeks. The potentially probiotic strain was proved capable of performing lactic acid fermentation at 30 °C. Cell viability of L. paracasei was detected in high levels during fermentation and the whole storage period, while the fermented juice showed higher levels of viability in juice with 40.3 g/L of initial sugar concentration. No ethanol was detected in the final fermented juice. Fermented chokeberry juice was characterized by aromatic desirable volatiles, which were retained in adequate levels for the whole storage period. Specifically, the occurrence of organic esters detected in fermented juices is considered as positive evidence of the provision of fruity and floral notes to the final product. During storage, total phenolics content and antioxidant activity were observed in higher levels in fermented chokeberry juice compared with non-fermented juice. Subsequently, fermentation of chokeberry juice by potentially probiotic lactic acid bacteria could provide high industrialization potential, providing the market with a nutritional beverage of good volatile quality with an enhanced shelf-life compared with an unfermented fresh juice.


2011 ◽  
Vol 28 (6) ◽  
pp. 1175-1181 ◽  
Author(s):  
Wei Xu ◽  
Zhiyong Huang ◽  
Xiaojun Zhang ◽  
Qi Li ◽  
Zhenming Lu ◽  
...  

2014 ◽  
Vol 8 ◽  
pp. 161-168 ◽  
Author(s):  
Stella A. Ordoudi ◽  
Fani Mantzouridou ◽  
Eleni Daftsiou ◽  
Christine Malo ◽  
Efimia Hatzidimitriou ◽  
...  

Author(s):  
Yang Chen ◽  
Ye Bai ◽  
Dongsheng Li ◽  
Chao Wang ◽  
Ning Xu ◽  
...  

Abstract Acetic acid fermentation is an essential step in the production of high-quality fruit vinegar and typically involves the use of acetic acid bacteria (AAB). The present study showed that the high cell mass and acetic acid yields of ethanol-tolerant AAB under high ethanol conditions were related to the high activities and stability of both pyrroloquinoline quinone (PQQ)-dependent alcohol dehydrogenase and PQQ-dependent aldehyde dehydrogenase. Additionally, in acetic acid fermentation with watermelon wine (8 % ethanol), the main organic acids (acetic, tartaric and malic acids) produced by ethanol-tolerant Acetobacter pasteurianus AAB4 were higher than those by conventional A. pasteurianus AS1.41 (1.42-fold, 3.53-fold and 2.12-fold, respectively). Also, the main esters (ethyl acetate and phenylethyl acetate) produced by AAB4 were higher than those by AS1.41 (1.69-fold and 1.48-fold, respectively). In addition, the total sweet and umami free amino acids produced by AAB4 increased significantly. According to sensory analysis, the flavor, taste and overall acceptance score of watermelon vinegar produced by AAB4 were significantly higher than those by AS1.41. Therefore, high ethanol fermentation with ethanol-tolerant AAB improved the flavor and quality of watermelon vinegar, indicating that this technology can be applied to fruit vinegar production.


2019 ◽  
pp. 299-325
Author(s):  
Isidoro García-García ◽  
Jorge E. Jiménez-Hornero ◽  
Inés María Santos-Dueñas ◽  
Zoilo González-Granados ◽  
Ana María Cañete-Rodríguez

2004 ◽  
Vol 67 (11) ◽  
pp. 2456-2464 ◽  
Author(s):  
I. M. BARMPALIA ◽  
I. GEORNARAS ◽  
K. E. BELK ◽  
J. A. SCANGA ◽  
P. A. KENDALL ◽  
...  

The antilisterial activity of sodium lactate (SL) and sodium diacetate (SD) was evaluated in a frankfurter formulation and in combination with a dipping treatment into solutions of lactic acid or acetic acid after processing and inoculation. Pork frankfurters were formulated with 1.8% SL or 0.25% SD or combinations of 1.8% SL with 0.25 or 0.125% SD. After processing, frankfurters were inoculated (2 to 3 log CFU/cm2) with a 10-strain composite of Listeria monocytogenes and left undipped or were dipped (2 min) in 2.5% solutions of lactic acid or acetic acid (23 ± 2°C) before vacuum packaging and storage at 10°C for 40 days. Total microbial populations and L. monocytogenes, lactic acid bacteria, and yeasts and molds were enumerated during storage. Sensory evaluations also were carried out on frankfurters treated and/or formulated with effective antimicrobials. The combination of 1.8% SL with 0.25% SD provided complete inhibition of L. monocytogenes growth throughout storage. Dipping in lactic acid or acetic acid reduced initial populations by 0.7 to 2.1 log CFU/cm2, but log CFU/cm2. For samples containing single antimicrobials and dipped in lactic acid or acetic acid, L. monocytogenes growth was completely inhibited or reduced over 12 and 28 days, respectively, whereas final populations were lower (P < 0.05) than those in undipped samples of the same formulations. Bactericidal effects during storage (reductions of 0.6 to 1.0 log CFU/cm2 over 28 to 40 days) were observed in frankfurters containing combinations of SL and SD that were dipped in organic acid solutions. Inclusion of antimicrobials in the formulation and/or dipping the product into organic acid solutions did not affect (P > 0.05) the flavor and overall acceptability of products compared with controls. The results of this study may be valuable to meat processors as they seek approaches for meeting new regulatory requirements in the United States.


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