Bioactive compounds are substances which are present in foods in small amounts and have the ability to provide health benefits. Bioactive compounds include but are not limited to long-chain polyunsaturated fatty acids, vitamins, carotenoids, peptides, and polyphenols. The aim of the present study is to review literature for potential bioactive compounds present in food waste material and discuss the transformation of food waste to animal feed under the perspective that usage of food waste, rather than disposal, may tackle food insecurity and provide health benefits. Finally, applications in poultry and swine nutrition, with emphasis on the presence of fatty acids on food waste material, are discussed.

During the previous decades, the growing demand for animal origin products has gained considerable attention. As a result, livestock breeding has faced a rapid intensification in order to fulfil market expectations. This increase in livestock production has led to a large scale of manure that is associated with many environmental impacts, such as climate change, to an increase of greenhouse gases (GHG) emissions. Livestock production is considered to generate significant amounts of GHG, mainly carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O). Methane and nitrous oxide are the main emissions from livestock systems. Ruminants contribute highly to total livestock emissions. In the present study, the contribution of livestock and especially of the small ruminants in GHG emissions is reviewed. Additionally, useful sustainable strategies for farming and feeding of small ruminants are highlighted. Some of the practices discussed include but are not limited to efficient manure management, the replacement of mineral fertilizers by farm manure, the improvement of feed efficiency and provision of feed supplements. Moreover, the use of food waste or agro-industrial by-products is discussed as a sustainable strategy.

Food waste valorization via its transformation into animal feed is a viable alternative for improving food security and the diversion of organic waste from landfills. The manuscript presents the environmental impact assessment of the construction and operation of a novel solar food waste drying unit on the island of Crete in Greece, which is treating food waste from hotels. Life cycle assessment is utilized for the impact assessment. The results indicate a total carbon footprint of approximately 217.5 kg CO₂ eq. per ton of treated food waste. In conclusion, the operation phase is the major contributor to the environmental impacts, due to the utilization of electricity.

Modern hydroponic substrates have contributed significantly to the popularity and progress of hydroponic cultivations worldwide, nevertheless, their development, transportation, and disposal often come at a significant environmental cost. Here we investigate the feasibility of partial to total replacement of conventional organic growing media constituents, such as cocodust (C), in a 20% perlite (P) and 80% cocodust substrate (hereafter control 8C), with compost from locally sourced grocery waste (W). For this purpose, four treatment mixtures were developed (6C:2W, 4C:4W, 2C:6W, 8W), with the grocery waste-compost fraction ranging from 20 to 80%, respectively (perlite constant at 20%). The new substrates were tested on hydroponic lettuce (Lactuca sativa var. Tanius) cultivation. During the 35-day experiment, lettuce physiology was evaluated using chlorophyll concentration [SPAD], chlorophyll fluorescence [Fv/Fm], number of leaves, and plant growth index. At harvest, the plant yield was evaluated using leaf area [cm²], leaf fresh and dry weight [g], as well as leaf firmness [g]. Results show that substrates with compost led to superior physiology and yield characteristics, with 8W inducing a significant increase in leaf area, chlorophyll concentration, dry weight, and firmness, by 11.6%, 5.4%, 19.8% and 12.8%, respectively, compared to the control treatment 8C. Results indicate that grocery waste-based compost is an excellent sustainable alternative for the soilless cultivation of lettuce. After its use in hydroponic cultivation, substrate material is safe to dispose of or be used as a soil amendment, thus contributing to a circular agro-food economy model.

An increasing world population along with increasing human needs have raised demand for animal origin products. Moreover, high prices of conventional animal feeds have led to a demand for alternative feedstuff. Food waste can be an alternative feed ingredient. The aim of the present study was to investigate the effect of dietary inclusion of dried hotel residues (DHR) on the growth performance, blood biochemical parameters and meat quality traits in finishing pigs. In each of the 2 trials conducted, 20 castrated male pigs were allotted into 2 treatments. In both trials, control treatment pigs were fed a corn-soybean meal-based diet without hotel residues. In the first trial, a DHR1 treatment contained 100 g DHR1/kg with meat residues (approximately 5%). In the second trial, a DHR2 treatment, contained 80 g DHR2/kg with no meat residues. Average daily feed intake tended to be lower and average daily weight gain was lower in DHR1 compared to control pigs in the first trial, while in the second no differences were detected. However, final body weight, FCR and dressing percentage were not affected in any of the two trials. Minor differences in several meat physical traits, hematological parameters were observed among treatments and trials. In conclusion, the results indicate that the dietary addition of DHR did not affect the feed utilization and the quality of the produced meat; hence, the use of DHR in pig feeding can be supported.

The potential use of food residues for pet food could significantly contribute to food waste reduction. In the present study, the effects of the inclusion of dried food residues (DFR) (0, 5, 10 and 15%) in a complete diet were evaluated in seven healthy adult cats. At the end of each three-week feeding period, feces were collected. The analysis of the fecal microbiota by 16S rDNA sequencing demonstrated a marked increase of the bacterial alpha-diversity with increasing dietary inclusion levels of DFR. In addition, an increase in the relative abundance of Coriobacteriales, Collinsella and Lachnoclostridum, as well as of propionate and n-valerate in the feces of the cats, was detected. The dietary inclusion of DFR decreased the apparent crude protein digestibility and tended to decrease the apparent crude fat digestibility. Overall, the DFR seemed to be highly fermentable in the intestine of cats, which markedly affected the diversity of the fecal microbiota. As this effect might be critical for a balanced gut microbiota, but also along with the observed depressing effects of DFR on the apparent crude protein and crude fat digestibility, lower inclusion levels are recommended if used as a potential ingredient for cat food in the future.