# Fermentation Efficiency and Profile of Volatile Compounds in Rye Grain Mashes from Crops Fertilised with Agrifood Waste Ashes

## TL;DR

This study explores how using agrifood waste ashes as fertilizer affects rye grain and its fermentation for alcohol production.

## Contribution

The study introduces the use of specific agrifood waste ashes to improve rye grain quality and fermentation outcomes.

## Key findings

- Ethanol yields from rye mashes ranged between 67.25% and 76.59% of theoretical maximum.
- A 50:50 ash mixture increased aldehyde levels significantly, reducing fermentation efficiency.
- Rye grain starch content was comparable to control samples despite ash fertilization.

## Abstract

The utilisation of agrifood waste ashes has the potential to enhance the nutrient content of cereal crops, thereby optimising both yield and grain quality. This study investigated rye grain composition, the fermentation efficiency, and volatile compounds in mashes made from crops fertilised with agrifood waste ashes derived from the combustion of corn cob, wood chips, and biomass with defecation lime. The ashes were applied at 2, 4, and 8 t/ha, separately and as mixtures of corn cob (25%) with wood chips (75%) and corn cob (50%) with biomass and defecation lime (50%). Rye mashes were prepared using the pressureless starch liberation method. The starch content in the majority of the rye grains was comparable to the control sample (57.12 g/100 g). The range of ethanol concentrations observed in the fermented mashes was from 55.55 to 68.12 g/L, which corresponded to fermentation yields of 67.25–76.59% of theoretical. The lowest fermentation yield was exhibited by the mash derived from rye cultivated on soil fertilised with a 50:50 mixture of ashes from corn cob and biomass with defecation lime at 8 t/ha. This mash contained more than double the acetaldehyde concentration and total aldehyde content compared to the other samples. These findings demonstrate the potential of using waste biomass ash as a source of macro- and microelements for rye cultivation, enabling the production of agricultural distillates. To ensure high fermentation efficiency and low aldehyde levels, ash dosage and composition need to be established based on experimental optimisation.