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Fermented Milk Products
Published in Debabrata Das, Soumya Pandit, Industrial Biotechnology, 2021
The major classifications of cheese and its types have been discussed briefly along with their nutritional information. The complete process of cheese production including the major steps such as milk standardization, pre-treatment, incubation of starter culture, the addition of rennet, salting etc. has been discussed in detail. A detailed study of yoghurt, the microorganisms in yoghurt, and the complete commercial process of yoghurt production such as homogenization, pasteurization, cooling etc. has been given. Probiotic foods and the characteristic lactic acid bacteria present in probiotics such as the Streptococcus–Lactococcus branch (Family Lactobacillaceae), Lactobacillus (Family Streptococcaceae) and probiotics in the form of different products such as acidophilus milk, bifidus milk, acidophilus-bifidus milk, mil-mil, yoghurt, yakult, kefir, cheese, koumiss/kumiss, miru-miru etc. and various compositions of milk have all been reviewed. Lastly, the advantages and disadvantages of different fermented foods were discussed.
Influence of initial pH on the production of volatile fatty acids and hydrogen during dark fermentation of kitchen waste
Published in Environmental Technology, 2021
Radosław Slezak, Justyna Grzelak, Liliana Krzystek, Stanisław Ledakowicz
Based on the conducted research, it was observed that the ammonia contained in the inoculum allowed buffering pH during the dark fermentation of KW. Increasing the initial pH resulted in a slight growth in operational pH, which was associated with a greater decomposition of organic matter, including proteins from which ammonia was formed. The conducted research allowed determination of the initial pH, at which the highest yield of VFAs and H2 production was obtained. The largest production of VFAs (about 14 g/L) was achieved at the initial pH of 8, and the content of acetic and butyric acids was 52 and 42%, respectively. Due to the high VFAs/TOC ratio (0.86) at the initial pH of 8, the production of ethanol and lactic acid was at a very low level. In contrast, the maximum production of H2 (82.6 mL/gVS) was achieved at a slightly lower initial pH of 7. However, the yield of H2 production at initial pH of 8 was 10% lower than maximum yield. For the initial pH of 8, the lag phase duration during H2 production increased to a value about 5 h compared to bioreactor in which initial pH was 7. During dark fermentation, CO2 was also formed, the production yield of which was close to that of VFAs. At the initial pH of 6, the highest growth of Lactobacillaceae bacteria was observed and at the initial pH of 8 Clostridiaceae one. Despite the presence of Lactobacillaceae bacteria at the initial pH of 8 no lactic acid production was observed. The increased production of VFAs and H2 for the initial pH of 8 resulted in a greater diversity of the microbial community. Dominant micro-organisms at the initial pH of 8 were Bacteroidetes, Firmicutes, Spirochaetes and WWE1 at the phylum level.