Proximate composition, Free amino acids and peptides contents in commercial chicken and other meat essences

Ten commercial meat essences of chicken, beef, clam and eel contained the moisture ranged from 91.1 to 97.5%, protein from 0.6 to 7.8%, and ash from 0.3 to 1.7%. Freshwater clam and hard clam essences had a much higher level of glycogen than other products. The total amount of free amino acids (FAA) in six chicken essences varied from 150 to 725 mg/100 g. Taurine was the dominant FAA and accounted for 16∼30% of the total FAA. Though beef essence had the highest level of total FAA among ten products, its taurine was accounted for only about 2%. Taurine in freshwater clam essence was also very low, but a high level of ornithine was found. Anserine in six chicken essences, ranging from 36 to 437 mg/100 g, was higher than carnosine, ranging from 8 to 162 mg/100 g. In beef essence, however, anserine was far less than carnosine. These dipeptides in both clam essences were not detectable, and only a small amount of carnosine was present in eel essence. Another dipeptide, balenine, was found only in a chicken essence. The amount of low-molecular-weight peptides in chicken essences, ranged from 1,187 to 3,296 mg/100 g, was more than the level of FAA in each product. Both clam essences contained a much lower amount of small peptides than other products. Consequently, hard clam essence was the only product with lower level of peptides than its FAA.