Abstract
Considering the global need for waste valorization and enhancing resource efficiency, this study investigated the possibility of recovering amino acids from underutilized chicken heads and legs as poultry by-products. In this sense, a new combined technique was developed based on ohmic heating (OH) and subcritical water (SCW), i.e., OHSCW. Besides, the effects of OH at different electric field strengths (5.71, 7.14, and 8.57 V/cm) and times (15, 30, and 45 min) were compared with the control treatment (SCW equipped with conventional heating, without OH) at a temperature of 140 °C. The results showed that the come-up time using OHSCW, at electric field strengths of 7.14 and 8.57 V/cm, was less than the control method by 17 and 75%, respectively. The lowest specific energy consumption was 403.68 kJ/kg which was 59.22% less than the control method. The highest energy efficiency was 93.88% at the electric field strength of 8.57 V/cm which was superior to that of the control treatment, i.e., 47.13%. The amounts of total amino acids recovered by OHSCW, at an electric field strength of 8.57 V/cm, were higher than the control method by 70.48%. OHSCW at an electric field strength of 5.71 V/cm yielded the maximum recovery efficiency of amino acids (79.40%) while recovery efficiency in control treatment was 15.48%. Besides, the results of Amino acid Analyzer (AAA) showed that the recovered amino acids include asparagine, serine, glutamine, glycine, threonine, histidine, cysteine, alanine, aspartic, tryptophan, arginine, tyrosine, valine, methionine, isoleucine, leucine, and phenylalanine. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13197-022-05556-4.