Sensory Quality and Protein Composition Analysis of Porphyra haitanensis in Different Harvest Periods

In order to investigate the effects of different harvesting time on the sensory and protein quality of Porphyra haitanensis, the changes of color, texture, protein content, amino acid content and free amino acid content were studied. The results showed that the L^* value, a^* value and b^* value of P. haitanensis in different harvest periods changed, in which the L^* value increased significantly, while the a^* value had no significant effect, and the b^* value of the second and third harvest was significantly higher than the first harvest. The toughness of P. haitanensis was not significantly affected by different harvest time, but the hardness and elasticity increased with the increase of harvest time. Free amino acids played a major role in the umami taste of P. haitanensis. The content of free amino acids of P. haitanensis in the first, second and third harvests was 1629.80, 1450.18 and 1155.13 mg/100 g, respectively. P. haitanensis had high protein with 39.38% in the first harvest, which was significantly higher than that of the second and third harvest. With the increase of harvest time, the contents of total amino acids, essential amino acid and non-essential amino acid amino acids in P.haitanensis decreased gradually. In summary, P. haitanensis has high nutritional value, and has better quality and higher umami taste in the early harvesting period. The results can provide a basis for the quality classification and utilization of P. haitanensis.