FLAVOURING INGREDIENT DERIVED FROM CHICKEN BONE HYDROLYSATES

The poultry industry plays an important role in the national and global economy, resulting in a large amount of by-products after slaughter process. The use of meat by-products through the enzymatic hydrolysis of proteins is well described in the literature, several refers the obtaining of flavour precursors of protein hydrolysates. The flavouring effect of protein hydrolysates is attributed to soluble low molecular weight compounds, i.e. free amino acids, sugars, and fatty acids. These compounds participate in several complex reactions, such as the Maillard reaction, lipid oxidation, and thiamine degradation. Chicken bones have a potentially promising chemical composition that favours their use as a potential ingredient. Therefore, the aim of this research was to develop a flavouring agent from protein hydrolysates of chicken bones to be used in food industry. For this purpose, a high-pressure pre-treatment of the bones was carried out. The partial chemical composition of heated bones was determined, followed by enzymatic hydrolysis using the Flavourzyme®. Finally, a flavouring ingredient was elaborated using the protein hydrolysate, enriched with thiamine, cysteine, and xylose, thermally treated in an autoclave. Volatile profile was carried out in heated bones, hydrolysates and flavouring by GC/MS. The chicken bones had high levels of proteins and lipids, 29.8 g/100g and 15.3 g/100g, respectively, contributing to the use of enzymatic hydrolysis in this matrix and to the generation of important precursors from the lipidic pathway. A total of 40 volatiles were identified in heated chicken bones, among them, the predominant chemical class was aldehydes (24), alcohols (8), ketones (6), pyrazines (2), hydrocarbons (2), furans (1), thiazoles (1), and pyridines (1). Nonanal, an important compound formed during the thermal hydrolysis of fatty acids, showed higher values in the hydrolysates, comparable to bones. Aldehydes considered important for the flavour of roasted chicken, such as hexanal, benzaldehyde, and decanal, also had higher average values in the volatile profile. It is known that aliphatic alcohols with unsaturated components with low detection limit contribute to meat flavour. Among them, 1-octen-3-ol, which is considered a key compound, showed higher average values in the hydrolysate. The release of flavour compounds, precursors by enzymatic hydrolysis contributed to the identification of important compounds in the flavouring ingredient from chicken hydrosalate. The reaction of the amine group with the carbonyl group of the added reducing sugar, cysteine, and free amino acids, during the heat process, resulted in the formation of rearranged and dehydrated glycosylamines leading to the formation of furfural, furanone derivatives, hydroxyketones and dicarbonyl compounds, which are essential for the determination of meat flavour. The 2-methyltetrahydrofuran-3-one identified in the aroma profile of flavouring ingredient acts as a flavouring agent and has a nutty note, as well as the 2-methyl-3-furantiol, which are referred to important descriptors such as roasted, nutty, potato, and fried meat, both compounds absent in the bones and hydrolysates volatile profile. The results showed the importance of the hydrolytic step of chicken bones, and the potential use of this by-product, as a food ingredient to be used as a basis for flavour compounds production.