Nutrients content of food wastes from different sources and its pre-treatment

Abstract

Food wastes are the most abundant waste available in Malaysia. Based on current households’ number of 7.67 million and a food waste generation rate of 0.54 kg/day per household [1], the amount of food waste generated is about 1.51 million tons/year. It is normally disposed of together with the municipal solid waste in a sanitary or non-sanitary landfill and incinerated without any recycle efforts. The dispose food wastes have high nutrient content that may be used as a fermentation substrate to produce other value-added product. However, the composition of daily collected food waste may vary and affect the fermentation performance and product quality. Moreover, limited information about its nutrients content from various sources can be found. Hence, this study aims to examine the extent of variation in the nutrients content of food wastes collected from different sources and also to evaluate the effect of hydrothermal pre-treatment on the nutrients composition of food wastes. Food wastes were collected randomly from the university’s café, Indian and Chinese restaurants, morning and night markets, and also from a household. It was then sorted, weighed, crushed and blended before further characterization. Food wastes from university’s café were then hydrothermal pre-treated at 120°C for 75 min at a food waste to water ratio of 1:2. Total solid and volatile solid contents and moisture content of various untreated and pre-treated food wastes were analyzed by Standard Method, while the composition of lipid was determined by Bligh & Dyer method. Protein and carbohydrate contents were determined by Bradford method and Phenol-sulphuric Acid method, respectively. Research outcomes showed huge nutrient variation between food wastes from different sources, which may due to the variation in the nature of the sources. Hydrothermal pre-treatment has reduced the total solid and volatile solid contents (32% and 24%, respectively) and maintained the amount of lipid content in the food wastes. Besides, the key media of fermentation which is the protein and carbohydrate contents were found increased by 107% and 152%, respectively in the pre-treated hydrolysate. The results showed that the hydrothermal pre-treated food waste can be used either as a feed medium or a supplemental medium for the fermentation process. Nevertheless, further investigation for controlling the composition in food wastes is needed if consistent nutrient contents are required. The results obtained in this study could be used as the foundation for further study in valorizing food waste for a better application.