The effect of anaerobic co-fermentation on acidification performance of food waste and cardboard waste

The fermentation system with high solid materials for food waste (FW) is uneven in nutrition and easy to produce volatile acid accumulation, which causes the reaction system to acidify and affects the normal operation of fermentation. This study evaluated the effect of the co-substrate percentages (FW:CB = 9:1, FW:CB = 8:2, FW:CB = 7:3) and the initial total solid contents (12%, 15%, 18%) on the co-fermentation acidification performance of FW and cardboard waste (CB). The maximum methane production was obtained when mono-fermenting FW had high solids contents(1.4 L/kg). The methane production increased and then decreased with the increasing percentages of CB. Under the conditions of FW:CB = 8:2, the maximum methane production could reach 3.4 L/kg. The lower methane production (1.8 ∼ 2.5 L/kg) with high percentages of CB (FW:CB = 7:3) was translated into higher yields of caproic acid (up to 26%), which indicated lower percentages of CB had a stabilization effect due to the higher buffering capacities in co-fermentation. As a result, this study demonstrated new possibilities for using CB percentages to control the production of high added-value biogas in dry co-fermentation of FW.

Meta-Analysis of Volatile Compounds from Vinegar Produced by the Slow Method and the Fast Method

Volatile compounds are one of the important characteristics of vinegar, where the content and composition of these compounds is an account for the aroma profile of vinegar. The difference in production technology used in making vinegar produces vinegar with different characteristics. There are two general methods commonly used in the production of vinegar, namely the slow method and the fast method. This meta-analysis was used to conclude several studies that examined the differences in volatile compounds in vinegar produced through the slow methods and the fast methods. From this study, it can be seen that comparison of volatile compounds characteristics in vinegar produced by the slow method and the fast method where the slow method tends to produce vinegar with a high concentration of acetate ester group and alcohol group, and the fast method tend to produced vinegar with a high concentration in a volatile acid group.

Optimization of Hydrolysis-Acidogenesis Phase of Swine Manure for Biogas Production Using Two-Stage Anaerobic Fermentation

The traditional pig manure wastewater treatment in Taiwan has been low in methane production efficiency due to unstable influent concentration, wastewater volume, and quality. Two-stage anaerobic systems, in contrast, have the advantage of buffering the organic loading rate in the first stage (hydrolysis-acidogenesis phase), allowing a more constant feeding rate to the second stage (methanogenesis phase). Response surface methodology was applied to optimize the operational period (0.5–2.0 d) and initial operational pH (4–10) for hydrolysis and acidogenesis of the swine manure (total solid 5.3%) at 35 °C in batch operation mode. A methanogenesis verification experiment with the optimal condition of operational period 1.5 d and pH 6.5 using batch operation resulted in peak volatile acid production 7 g COD/L, methane production rate (MPR) 0.3 L-CH4/L-d, and methane yield (MY) 92 mL-CH4/g-CODre (chemical oxygen demand removed). Moreover, a two-stage system including a hydrolysis-acidogenesis reactor with the optimal operating condition and a methanogenesis reactor provided an average MPR 163 mL/L-d and MY 38 mL/g volatile solids, which values are 60% higher than those of a single-stage system; both systems have similar dominant methane-producing species of Firmicutes and Bacteroidetes with each having around 30%–40%. The advantages of a two-stage anaerobic fermentation system in treating swine manure for biogas production are obvious.

Highland Barley Replaces Sorghum as Raw Material to Make Shanxi Aged Vinegar

Highland barley (HB, Hordeum vulgare L. var. nudum Hook. f.), also known as naked or hulless barley, is a kind of cereal crop growing at high altitudes (4200–4500 m) around the world. In this study, HB vinegar (HBV) was prepared, using Tibetan HB as the main raw material, according to the process of Shanxi aged vinegar (SAV), a famous vinegar in China, in which sorghum is usually used as the main raw material. The related main compounds, such as alcohol and acetic acid, in the alcohol and acetic acid fermentation processes were monitored and analyzed, respectively. The flavor components in the aged vinegars were analyzed by headspace solid-phase microextraction, combined with gas chromatography-mass spectrometry, and compared with sorghum vinegar (SV), which was made, using sorghum as the raw material, based on the SAV process. The results revealed that at the alcohol fermentation stage, the alcohol content of HB mash was higher than that of the sorghum mash (p < 0.05), and at the acetic acid fermentation stages of HBV and SV, the total acid contents were 6.23 and 5.81 (g·100 mL−1 and p < 0.05), respectively. After aging one and a half years, the contents of non-volatile acid, volatile acid, and ester compounds in HBV were higher than those in SV. Therefore, HB can replace sorghum as the raw material for making SAV. Based on a literature search, the comparison and analysis of the main components and volatile flavor compounds of HBV and SV were not studied before.

THE INFLUENCE OF DISTILLATION METHODS ON THE FLAVOR PROFILE AND QUALITY INDICES OF WINE BRANDIES

The article examines the geographical area delimited for the production of the Divine and the specific characteristics and physical-geographical conditions of the Călărași vineyard through the prism of different methods of distillation and production of wine distillates. Technological regimes for distilling wine raw materials and organoleptic and physico-chemical indices such as: alcohol content, optical density, pH, aldehyde content, higher alcohol content and volatile acid content are scientifically argued. The quality indicators were determined for both wines and distillates obtained at the 'Charente' batch plant and the 'VAND-M-0' plant. The impact of the distillation method on the quality and production process of the wine distillate is evaluated.

Fermentation profiling of rice wine produced by Aspergillus oryzae KSS2 and Rhizopus oryzae KJJ39 newly isolated from Korean fermentation starter

The objective of this study was to determine the fermentation characteristics of rice wine produced by koji inoculated with Aspergillus oryzae KSS2 and Rhizopus oryzae KJJ39 on moisturized wheat-bran and rice grain. We also compared rice wine samples produced in this study and three commercial Makgeolli. The alcohol content was about 12% higher in the rice wine samples fermented by wheat-bran koji than in the other samples. In all of the samples, the range of pH value was 3.8–4.6 and the total acid was below 0.5. The soluble solid content was highest in the rice wine sample prepared by the wheat-bran R. oryzae KJJ39 koji (15.5°Brix) and overall relatively higher in the samples with wheat-bran koji than rice koji. The content of reducing sugar was twofold higher in rice wine prepared by koji inoculated with R. oryzae KJJ39 than A. oryzae KSS2. The volatile acid content was higher in rice wine produced by the wheat-bran A. oryzae KSS2 koji than the others. In the analyses of five organic acids, A. oryzae KSS2 was found to produce more malic acid and fumaric acid while R. oryzae KJJ39 to do more citric acid, lactic acid and acetic acid. The rice wine sample prepared with the wheat-bran A. oryzae KSS2 koji contained much higher concentration of sucrose, maltose and amino acids. Comprehensively, the results of fermentation profiling suggest that both A. oryzae KSS2 and R. oryzae KJJ39 can be applied to the production of rice wine as a valuable fungal isolate for fermentation start.