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Synergistic fermentation of coal and corn straw is an effective tool to increase biomethane production. However, a large gap exists between the biomethane production conditions of corn straw filling coal mine goafs and laboratory experiments. In order to determine the effect of the field environment on synergistic biomethane production, biomethane production experiments with coal and corn straw were carried out under different conditions to find the key factors restricting the potential of biomethane production. The obtained results showed that various bacterial sources had significant influences on the biomethane production of coal and corn straw, and domesticated bacterial sources provided fermentation systems with more efficient biomethane production capacities than mine water sources. Biomethane production of coal and corn straw was relatively high under mixed conditions, but it was also promoted under unmixed conditions. Different inorganic minerals had different effects on synergistic biomethane production, which varied. For example, calcite, montmorillonite, and kaolin are common minerals in coal‐bearing strata that significantly enhance synergistic biomethane production of coal and corn straw. However, pyrite was found to significantly inhibit the synergistic biomethane production effect of coal and corn straw. Highly metamorphosed anthracite coal also presented biomethane production potential when stimulated by corn straw as a carbon source. The obtained results revealed the influences of different field conditions on the biomethane production of coal and corn straw and provided a reference for the field application of corn straw filling in coal mine goafs. [ABSTRACT FROM AUTHOR]

BACKGROUND Beef potentiator ( BP) is the most popular savoury flavour and regarded as the soul of the modern food industry. In this work, BP was prepared by a novel method with Aspergillus oryzae and Aspergillus niger ( BPSF). Three other BPs prepared using commercial enzymes (Protamex, Flavourzyme and papain; BPCEs) were used as controls to investigate its aroma characteristics and related compounds. RESULTS Sensory evaluation showed that BPSF possessed more favourable and distinctive sauce-like, meat-like, roast and alcoholic attributes when compared with BPCEs. Significantly higher contents (peak areas) and proportions of pyrazines, pyrroles, sulfurous compounds and alcohols in BPSF were responsible for its sensory characteristics, and most of these aroma compounds were derived from microbial metabolism during beef koji preparation and the Maillard reaction. CONCLUSION BP prepared by synergistic fermentation with A. oryzae and A. niger is a potential alternative for BP preparation. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Beef potentiator was prepared by beef qu, which was previously prepared by a novel synergistic fermentation method ( BPSF). Three kinds of other beef potentiators were prepared by commercial enzymes (protamex, flavourzyme and papain, BPCEs), which were used as controls to investigate the physicochemical properties of BPSF. Results showed that BPSF possessed a higher protein recovery (70.99%) and degree of hydrolysis ( DH, 51.39%) than BPCEs. The tests of molecular weight distribution and free amino acids ( FAAs) indicated that the moderate molecular weight peptides (1-5 kDa) were dominant (70.07-74.43%) in all beef potentiators. The low molecular weight peptides (<1 kDa), umami amino acids and total amino acids in BPSF, were 1.03- to 5.56-, 5.25- to 26.50- and 1.57- to 4.79-fold higher than those in BPCEs, respectively. Meanwhile, hierarchical cluster analysis indicated that BPSF was significantly different to BPCEs, and sensory evaluation showed that BPSF had apparently stronger umami taste than BPCEs. [ABSTRACT FROM AUTHOR]