Effects of Chemicals on Preservation of Crab-Processing Waste and Fermentation Characteristics of the Waste−Straw Mixture

Addition of 1.5% propionic/formic acid (1:1) prevented degradation of crab-processing waste for up to 14 days. The preserved waste was ensiled with wheat straw, sugarcane molasses, and water (32:32:16:20, wet basis) with or without 0.1% microbial inoculant. Reductions in pH and water soluble carbohydrates (WSC) and an increase in lactic acid were achieved in silages made with or without inoculant. Preserving crab waste with either 0.2% sodium hypochlorite (NaOCl) or 0.4% hydrogen peroxide (H2O2) prevented deterioration for up to 7 days. The concentration of trimethylamine (TMA), which indicates offensive odor in marine products, increased (P < 0.05) from 3.70 to 12.85 mg of N/100 g in NaOCl-treated waste, compared to no change (2.66 vs 2.71 mg of N/100 g) for H2O2-treated waste. The use of 1% sodium nitrite (NaNO2) and a combination of 0.2% NaOCl/0.2% calcium hypochlorite [Ca(OCl)2] (1:1, w/w) or 0.2% of each alone preserved the waste for a minimum of 10 days. Ammonia gas was first detected at day 12, and H2S was not detected throughout the 15 days of preservation with 1% NaNO2. Some chemicals show promise for preserving crab waste. Keywords: Trimethylamine; chemicals; hydrogen sulfide; ammonia; degradation