Preservation of Agri-Food Byproducts PDF

Waste Management 186 (2024) 109–118 Contents lists available at ScienceDirect Waste Management jou...

Waste Management 186 (2024) 109–118 Contents lists available at ScienceDirect Waste Management journal homepage: www.elsevier.com/locate/wasman Research Paper Preservation of agri-food byproducts by acidification and fermentation in black soldier fly larvae bioconversion Giacomo Alciatore a, b, Daniela A. Peguero a, b, Moritz Gold a, *, Christian Zurbrügg b, Mutian Niu c, Franco Bargetze d, Alexander Mathys a a ETH Zurich, Institute of Food, Nutrition and Health, Laboratory of Sustainable Food Processing, Schmelzbergstrasse 9, 8092 Zurich, Switzerland b Eawag: Swiss Federal Institute of Aquatic Science and Technology, Sandec: Department Sanitation, Water and Solid Water for Development, Überlandstrasse 133, 8600 Dübendorf, Switzerland c ETH Zurich, Institute of Agricultural Sciences, Animal Nutrition, Universitätstrasse 2, 8092 Zurich, Switzerland d REPLOID Schweiz AG, Lerchenfeldstrasse 3, 9014 St. Gallen, Switzerland A R T I C L E I N F O A B S T R A C T Keywords: Maintaining a consistent supply of feedstock for efficient bioconversion of black soldier fly larvae (BSFL) presents Hermetia illucens challenges due to the fluctuating availability of biowastes and agri-food products. To address the challenge of Pretreatment consistent feedstock supply for BSFL, this study investigated the influence of three preservation methods: wild Fermentation fermentation, inoculated fermentation, and acidification on agri-food by-products applied over three storage Food waste durations (1, 7, and 14 days), evaluating their impact on BSFL bioconversion, and feedstock nutrient and microbiota composition. The preserved feedstocks were characterized for gross nutrient, sugar, fermentation metabolite, and bacterial community analyses. All feedstock preservation methods and storage durations had a high bioconversion rate (21–25 % dry mass) and wet larval mass (170–196 mg). Notably, 7-and-14-day acidified feedstock had a significantly higher bioconversion rate compared to fermented feedstock. Acidification preserved feedstock nutrients best with only a 10 % difference compared to initial nutrient values. Fermentation produced typical lactic acid fermentation metabolites with reducing sugar contents; however, adding a lactic acid bacterial inoculum (7 log10 CFU kg feedstock− 1) had no benefit, presumably due to the high nutrient content and existing richness in lactic acid bacteria. Preservations had little influence on Enterobacteriaceae (6.2–7.5 log10 CFU g− 1) in freshly harvested larvae. Future research should assess the acidification and fermentation of different BSFL feedstocks and investigate the roles of feedstock pH, organic acids, and fermentation metabolites in more detail. Therefore, this study advances toward reliable and efficient insect-based nutrient recovery from agri-food by- products within the food system. 1. Introduction mass (DM) (Lalander et al., 2019), and converting it into a protein- and fat-rich larval biomass with value as feed for livestock (pigs and poultry) In recent years, the global food supply chain has become more (Barragán-Fonseca et al., 2017; Heuel et al., 2021), aquaculture (Mohan complex driven by factors such as market globalization, consumer de­ et al., 2022) or pets (birds and dogs) (Bosch et al., 2014). Moreover, they mands and the increase in income (Priefer et al., 2016). This trend has produce frass, a byproduct enriched with nutrients and beneficial mi­ resulted in more intermediaries in the supply chain, longer distances croorganisms that enhance plant growth (Fuhrmann et al., 2022; between producers and consumers and greater food losses, with about Gärttling & Schulz, 2022; Lopes et al., 2022). BSFL offers an alternative one-third of food produced being wasted globally (Blakeney, 2019; biological treatment technology for the increased global production of Priefer et al., 2016). The environmental impacts associated with food biowaste, while also producing a protein source potentially more sus­ production are magnified when the food is wasted. Black soldier fly tainable than traditional protein sources (soybean and fishmeal) (Sme­ larvae (BSFL, Hermetia illucens L, Diptera: Stratiomyidae) have emerged tana et al., 2019, 2021). as a promising insect for biowaste treatment, reducing up to 85 % dry For an efficient large-scale BSFL bioconversion facility (operations * Corresponding author. E-mail address: [email protected] (M. Gold). https://doi.org/10.1016/j.wasman.2024.05.043 Received 11 March 2024; Received in revised form 5 May 2024; Accepted 25 May 2024 Available online 13 June 2024 0956-053X/© 2024 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). G. Alciatore et al. Waste Management 186 (2024) 109–118 exceeding treating > 20,000 t feedstock year− 1), the consistent supply of An alternative feedstock preservation method, acidification, involves feedstock is crucial to producing reliable, high-quality feed and fertil­ the addition of organic acids to the feedstock to decrease pH to below 4.5 izer. This presents a challenge when using biowastes and agri-food to limit microbial growth (Pearlin et al., 2020). Gaining popularity as a byproducts, such as fruit, vegetables and surplus food, due to their valuable alternative to antibiotics, whose use in animal husbandry is intrinsically variable production. These variations occur for reasons being restricted in several countries, acidification offers immediate including fluctuating harvest periods, production schedules of the food effectiveness, reliably consistent results compared to fermentation and industry, changes in surplus food production based on current demand, effective nutrient preservation. However, unlike fermentation, it does and collection intervals of municipal organic solid waste (Armington not enrich the feedstock with potentially beneficial lactic acid micro­ et al., 2020). Particularly for nutrient-rich feedstocks in warm climates, organisms, probiotics and fermentation metabolites. storing these biowastes and agri-food by-products to balance production Given the potential benefits of feedstock preservation methods, this can lead to undesirable consequences, such as foul odor, attraction of study investigated the effects of acidification and two types of fermen­ pests and proliferation of pathogens. Consequently, BSFL bioconversion tation (e.g., wild and inoculum-based) on BSFL rearing performance and is currently more common for homogenous agri-food byproducts with product composition (larvae and frass). We hypothesized that while stable all-year quantities (starch, brewery, and ethanol byproducts both acidification and fermentation preserve feedstocks by lowering the based on wheat, maize, or rice) than agri-food byproducts or biowastes pH, fermentation is more advantageous for BSFL growth due to the variable in production quantities (surplus food and fruit and vegetable production of metabolites during fermentation. Therefore, this study wastes). This is despite the fact that management of heterogenous bio­ evaluated the effects of acidification and fermentation on feedstock wastes is a greater necessity due to the association with poor public and nutrients, fermentation metabolites, and the feedstock microbiome. We environmental health impacts and economic losses (Chen et al., 2020; also hypothesized that fermented feedstock may lower pathogens in the Hoornweg & Bhada-Tata, 2012). fresh harvested larval product, which could be beneficial for industrial Fermentation, a traditional method for food and feed preservation, producers in decreasing the energy and time required to ensure product commonly utilizes lactic acid fermentation as one of its prevalent safety. This research aims to establish reliable and efficient insect-based methods. This process involves the conversion of sugars into fermenta­ nutrient recovery of agri-food by-products within the food system using tion products, mainly short-chain fatty acids, such as lactate. Such BSFL. transformation results in an acidic pH (