The Monthly Digest – Food waste – April 2017

Food wastes and by-products
R & D abstracts – April 2017
Wastes and by-products: Upcoming sources of carotenoids for biotechnological purposes and health-related applications

Bioresidues valorization has gained a pivotal relevance in the last years, directly moved by consumers’ demands for heathier and safer products (food, cosmetics, supplements, drugs, and so on) and by industrial companies that need to adapt their manufacturing procedures to increasingly strict regulatory guidelines. Most of the natural ingredients are considered more sought and safer than synthetic ones, but also more expensive and less abundant. Therefore, the recovery of valuable active ingredients from wastes and by-products may be an interesting and upcoming strategy. The present report aims to provide an extensive approach to bioresidues valorization, focusing its chemical composition in terms of carotenoids content and their upcoming uses for biotechnological purposes. Daily produced and discharged industrial bioresidues derived from vegetable (peel, seeds, pericarp) and animal (wastewater, crustacean’s cephalothorax and carapace, scales, tails) sources comprise the richest sources of carotenoids (carotenes and xanthophylls). Different techniques are commonly used for carotenoids recovery being the extraction with organic solvents the most frequently used. Supercritical fluid extraction, microwave- and enzyme-assisted extractions are applied, but mainly in combination. This area opens fascinating opportunities to discover and to design novel strategies for carotenoids production/accumulation, foodstuffs valorization and provide valuable ingredients to different industrial sectors.

Martins N and Ferreira CFR (2017) Trends in Food Science and Technology 62:33-48

Bioenergy potential from food waste in California

Food waste makes up approximately 15% of municipal solid waste generated in the United States, and 95% of food waste is ultimately landfilled. Its bioavailable carbon and nutrient content makes it a major contributor to landfill methane emissions, but also presents an important opportunity for energy recovery. This paper presents the first detailed analysis of monthly food waste generation in California at a county level, and its potential contribution to the state’s energy production. Scenarios that rely on excess capacity at existing anaerobic digester (AD) and solid biomass combustion facilities, and alternatives that allow for new facility construction, are developed and modeled. Potential monthly electricity generation from the conversion of gross food waste using a combination of AD and combustion varies from 420 to 700 MW, averaging 530 MW. At least 66% of gross high moisture solids and 23% of gross low moisture solids can be treated using existing county infrastructure, and this fraction increases to 99% of high moisture solids and 55% of low moisture solids if waste can be shipped anywhere within the state. Biogas flaring practices at AD facilities can reduce potential energy production by 10 to 40%.

Breunig HM et al (2017) Environmental Science and Technology 51:1120-1128

Utilization of inulin-containing waste in industrial fermentations to produce biofuels and bio-based chemicals

Inulins are polysaccharides that belong to an important class of carbohydrates known as fructans and are used by many plants as a means of storing energy. Inulins contain 20 to several thousand fructose units joined by β-2,1 glycosidic bonds, typically with a terminal glucose unit. Plants with high concentrations of inulin include: agave, asparagus, coffee, chicory, dahlia, dandelion, garlic, globe artichoke, Jerusalem artichoke, jicama, onion, wild yam, and yacón. To utilize inulin as its carbon and energy source directly, a microorganism requires an extracellular inulinase to hydrolyze the glycosidic bonds to release fermentable monosaccharides. Inulinase is produced by many microorganisms, including species of Aspergillus, Kluyveromyces, Penicillium, and Pseudomonas. We review various inulinase-producing microorganisms and inulin feedstocks with potential for industrial application as well as biotechnological efforts underway to develop sustainable practices for the disposal of residues from processing inulin-containing crops. A multi-stage biorefinery concept is proposed to convert cellulosic and inulin-containing waste produced at crop processing operations to valuable biofuels and bioproducts using Kluyveromyces marxianus, Yarrowia lipolytica, Rhodotorula glutinis, and Saccharomyces cerevisiae as well as thermochemical treatments.

Hughes SR et al (2017) World Journal of Microbiology and Biotechnology 33:78

Effect of seasonal variations of organic loading rate and acid phase on methane yield of food waste leachate in South Korea

The objective of this study was to determine the effect of seasonal variations of organic loading rate (OLR) and acidogenic phase on methane yield of food waste leachate (FWL) treated in biogas facility in South Korea. A biogas facility operating in G city was selected as the target for this study. Remarkable seasonal fluctuations in methane yield occurred in this facility repeatedly. Methane yield in the summer was significantly lower compared to that in other seasons. In order to determine the operation efficiency, precision investigation (methane yield, OLR, etc) was conducted from March 2014 to April 2015. Characteristic parameters and operating factors of a two-stage anaerobic digestion were analyzed to obtain volatile fatty acids (VFAs), chemical oxygen demand, nutrients, total nitrogen, and so on. Data comparison revealed that the monthly average values of OLR and VFAs tended to increase rapidly in the summer (up to 3.92 kgVS/m3 day and 9263 mg/L, respectively). In contrast, methane yield in the same season was at 0.28 Sm3CH4/kg VS, which was much lower than the average value (0.42 Sm3CH4/kg VS) of methane yield in other seasons. The decrease in methane yield ranged from 69.0 to 57.9% in the summer. These results suggested that methane yield might be influenced by the operating conditions with seasonal organic loading fluctuations. In other words, methane yield might be affected by a shock load of VFAs due to inapposite operation of acidogenic phase with easily degradable FWL, particularly in the summer. The results of this study will provide important information on how an ongoing biogas facility of FWL should be operated in the summer.

Lee DJ et al (2017) Applied Biological Chemistry 60:87-93