Evaluation and optimization of salted wakame processing conditions using the response surface methodology

SOLANA, VALERIA; TOMAS, MABEL; DELLATORRE, FERNANDO GASPAR; IXTAINA, VANESA

Buenos Aires

Congreso; 11th WORLD CONGRESS OF CHEMICAL ENGINEERING; 2023

UCA Argentina

The edible seaweed Undaria pinnatifida (Undaria hereafter) has been consumed in Southwest Asia since ancient times. Among the main products for human consumption derived from this brown seaweed is blanched and salted wakame, whose quality is mainly related to its color and texture (especially hardness). The objective of this work was to study the effect of wakame processing variables (temperature (T), cooking time (t) and salt concentration during dehydration (S)) on the quality of the final product. The material used (30 Undaria plants) was collected by SCUBA diving on the southwest margin of the Golfo Nuevo (42.80° S, 64.92° W). The central zone of the blade was used. It was separated into 10-15 pieces of similar size (pinnae), mixed and used as replicates. The process for obtaining wakame was based on that described by Yamanaka and Akiyama [1]. The color (CIE L*a*b* scale) and hardness (gf) of the divided and undivided part of the blade were measured as output quality variables. The response surface methodology (RSM) was applied using a central composite face-centered design (CCD) with 3 factors and 3 levels for each factor: T (65, 80 or 95°C), t (20, 70 or 120 s) and S (20, 30, 40%). The experimental design included 17 combinations of processing conditions, with 8 factorial points, 6 axial points, and 3 replicates of the central point. A second order polynomial equation was used to express each quality parameter as a function of the independent variables. After regressing each predictive model, a residual analysis was carried out to validate the assumptions used. The model was checked using a lack of fit test and the coefficient "adequate precision". Through the global convenience function, the hardness in both regions of the blade was maximized and the color parameter a* was minimized (greener wakame). The results showed that the maximum hardness level was 342.5 and 404.6 gf for the divided and undivided part of the blade respectively, corresponding to the minimum levels of T (65 °C), t (20 s) and S (20 s). %). The t factor inversely affected the hardness of both regions of the blade, while T also had an inverse influence on the hardness of the undivided part of the blade; S through its quadratic term positively affected the texture of the divided part of the blade. Some interactions between the factors studied were also recorded. The values of a* were found in a range of -6.87 and 0.35 for the divided part of the blade, and -6.72 and 1.27 for the undivided part, obtaining greener wakame with lower T and highest t. In the case of a* of the undivided part, in addition to t, a significant effect of S was observed. An effect of the quadratic term of T and TxS interaction was also observed. The multiple optimization of the processing conditions to obtain wakame showed that the optimal combination corresponded to 68 °C, 31 s, 21 % salt, presenting a global convenience value D = 0.782. Thus, the information obtained is of interest for future scaling at an industrial level.