Study Of Seafood Condiment Of Polypeptide From Clam (Meretrix Lusoria)

Clam (Meretrix Lusoria), with the ancient name of Dong Ao or Chang E, belonging to Meretrix genera in bivalves, is a kind of marine shellfish mollusc. Due to its nutrition and taste, Meretrix as a delicious meal is popular with Chinese. However, fresh clam meat corrupts easily thus not easy to preserve, which leads to this unique resource have not been achieved economic and social benefits in China. In this work, two proteinases had been selected to hydrolyze clam meat and the two-stage enzyme hydrolysis reaction was optimized regarding to the concentration of peptide. Moreover, the total free amino acids and volatile components of hydrolysate and water extract were compared. On this basis, the flavor score of mixture with other condiments was determined to obtain the optimum formula of clam flavoring.Hydrolysis time, added enzyme quantity of trypsin, papain, refined neutral protease and pepsin were studied respectively in the single factor experiment. The optimal trypsin hydrolysis was obtained as following:added enzyme quantity0.6%(raw material), hydrolysis time50min, and the content of peptide obtained from hydrolysates was8.74mg/mL. The optimal papain hydrolysis was obtained as following conditions:added enzyme quantity0.8%(raw material), hydrolysis time1h, and the content of peptide was12.17mg/mL. The optimal hydrolysis of refined neutral protease was obtained as following conditions:added enzyme quantity8%(raw material), hydrolysis time1h, and the content of peptide was9.50mg/mL. The optimal hydrolysis was obtained with pepsin at the following condition:added enzyme quantity1.2%(raw material), hydrolysis time3h, but the content of peptide was not measured. At last, papain and refined neutral protease were selected for the two-stage enzyme hydrolysis process.Through single-factor and orthogonal experiments, hydrolysis temperature30℃, added enzyme ratio1:10, hydrolysis time ratio1:1and liquid-solid ratio (V/W)1:30were studied in the two-stage enzyme hydrolysis process of papain and refined neutral protease. The confirmation experiment indicated that the result of two-stage enzyme reaction (13.624mg/mL) was better than that of the single-enzyme hydrolysis (9.164mg/mL,10.283mg/mL), with3.4times higher than the peptide content of water extract.Compared with the water extract (111.4μg/mL), the content of free amino acids in hydrolysates was increased by101%(223.9μg/mL). Amino acid analysis results showed that the content of flavor amino acids in free amino acids reached to41.01%, and42.37%of flavor amino acids was presented as the form of peptides in the enzyme solution. Headspace solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) was used for volatile components analysis of hydrolysates and water extract. The content of small molecule substance such as hydrocarbons, aldehydes, alcohols and ketones in hydrolysates was much more than that in water extract. The enzyme solution contained extra five kinds of esters which greatly increased the flavor and coke of meat hydrolyzate.The optimum formula of clam flavoring was determined using the sensory evaluation test:added quantity of enzyme solution20%, monosodium glutamate25%, sugar20%and salt5%, as well as other condiments. Moreover, the indexes of sensory and heavy metal content can meet the national hygienic standard for aquatic flavoring. Therefore, the clam flavoring was proven with excellent taste characteristics and food security.