Fermentation

Regional assessments of livestock manure often treat excreted organic matter as available feedstock and methane volume as an unequivocal climate benefit. This study builds a four-level resource cascade (theoretical, collectable, recoverable, and deployment-constrained methane) for 20 Latin American countries from 2024 FAOSTAT inventories of cattle, pigs, and poultry with IPCC-consistent parameters, and evaluates each level across energy, exergy, nitrogen, and climate. The theoretical envelope of 73.88 × 10⁹ m³ CH₄ a⁻¹ contracts by 82.1% to 13.22 recoverable and to a deployment corridor of 6.74 (95% interval 5.05–9.27); cattle fall from 85.4% of the theoretical to 32.5% of the recoverable resource, whereas poultry rises to 40.4%, a share conditional on controlling ammonia inhibition. Energy and climate hierarchies diverge: pigs hold 27.1% of recoverable methane yet deliver all positive manure-management mitigation (+29.14 Mt CO₂eq a⁻¹ at 5% leakage), and the central net balance including grid displacement is +43.96 Mt CO₂eq a⁻¹, with a production-based break-even leakage of 15.00%. On an exergy-equivalent basis (81.52 TWh_x a⁻¹), recovered nitrogen (25.26 TWh_x; 3.77 Mt N a⁻¹) exceeds useful heat (10.24 TWh_x). Monte Carlo propagation (20,000 iterations) identifies cattle collectability as the dominant resource uncertainty (Spearman ${\rho }_s=0.774$) and digester leakage as the dominant climate uncertainty (${\rho }_s=-0.613$; 99.4% probability of positive management mitigation). Intensification scenarios raise recoverable methane to 16.97–20.73 × 10⁹ m³ a⁻¹ by 2035, and published techno-economic evidence shows that profitability depends on scale, incentives, and coproducts. Abundance, recoverability, climate effectiveness, and economic viability are four distinct quantities that must be evaluated jointly.

Mushroom mycelium is gaining attention as a sustainable protein source because it can be produced reliably through submerged fermentation and has a low environmental impact. In this study, we investigated the physicochemical and sensory characteristics of plant-based (PB) patties formulated with Lentinula edodes mycelium (LM) and pork backfat at respective levels of 15/0, 10/5, 5/10, and 0/15% (w/w, wet basis), based on the total formulation weight, and compared them with pork patties. Proximate composition analysis showed that the PB patty treatments had lower fat content (0–10.68%) than the control (p < 0.05). The water-holding capacity of the treatment groups was approximately 1.8 times that of the control (p < 0.05). The treatment groups exhibited generally lower texture profile values compared to the control. Electronic nose analysis showed that higher LM inclusion was generally associated with greater peak intensities for tentatively assigned volatile compounds, including ethanol, dimethyl sulfide, ethyl acetate, 3-methylbutanal, and hexanal. Electronic tongue analysis results showed that sourness and umami increased as the LM content increased. Sensory evaluation revealed no significant differences in overall acceptability among the treatments (p > 0.05). These results suggest the feasibility of developing low-fat plant-based patty formulations using LM.

The dairy industry produces large quantities of lactose-rich residues which could be fermented into a suite of valuable products. In this study, we sought to ferment concentrated cheese whey (CCW), with an initial lactose concentration of about 150 g/L, into D-lactic acid (D-LA) using an engineered strain of Lactiplantibacillus plantarum ATCC BAA-793 that lacks the L-lactate dehydrogenase gene (ldhL1), referred to as LdhL1. In experiments using lactose-supplemented laboratory MRS media, greater than 99% of the lactic acid generated by LdhL1 was the D-stereoisomer, compared to equimolar production of D- and L-lactic acid (L-LA) with the wild-type (WT) strain. When CCW was used as the major source of lactose and essential nutrients, most lactose was fermented in 7 days. However, in mixtures of CCW and MRS, fermentations with high-density LdhL1 cultures took less than 1 day, yielding D-LA titers of ~75 g D-LA/L, with 94% of the LA being the D-LA isomer, and with a production rate of ~3.7 g D-LA/(L h). This fermentation process achieves some of the highest titers and rates of D-LA production from dairy residues, an important step toward valorizing lactose-rich dairy residues.