Production of Flavorant and Colorant from Pacific White Shrimp (Litopenaeus vanamei) Head and Their Food Applications

Abstract

Study of shrimp head utilization for flavorant and colorant productions, the pretreatment of Pacific white shrimp (Litopenaeus vanamei) head for melanosis prevention was conducted. Soaking shrimp head in 0.5, 1.0, 2.0% citric acid solutions and 1.0, 2.0, 4.0% sodium metabisulfite solutions in the ratio of 1:5 w/v for 10, 15 and 20 min were compared. The results showed that PPO activity and melanosis score of the samples were decreased with increasing in solution concentration and soaking time (p<0.05). The sample treated with 2.0% sodium metabisulfite solution for 15 min obtained the lowest PPO activity and melanosis score. Moreover, the values were lower than of heated sample (core temperature of 80°C for 30 sec) (p<0.05). To produce the shrimp flavorant from Pacific white shrimp head, the optimal condition of enzymatic flavorant extraction from shrimp head using 0.15% w/w Alcalase (pH 8.0) or Flavourzyme (pH 7.0) at 55°C for 5 hr were studied. The results showed that extraction for 270 min yielded the highest protein and formaldehyde nitrogen contents for both enzymes (p<0.05). A descriptive analysis indicated that the flavorant using Flavourzyme gained higher intensity of boiled blue swimming crab odor, but lower intensities of boiled sundried shrimp and roasted sundried shrimp odors than that using Alcalase. The overall and color acceptance scores (n=30) of fish ball added with 4% (dry weight) flavorant extracted by Alcalase were higher than that by Flavourzyme (p<0.05). The flavorant solution from the non-pretreated sample had the higher protein and formaldehyde nitrogen contents than another and overall acceptance score of the pretreated sample was higher than that of non-pretreated sample (p<0.05). The shrimp flavorant using Alcalase, dried with different drying methods (freeze drying (FD), tray drying (TD) and spray drying (SD)) and the 20% flavorant solutions (20) and the 15% flavorant solution with 5% maltodextrin added (15+5M) were compared. The acceptance test indicated that drying methods had no effect on odor and flavor/taste liking scores of fish ball added with 4% shrimp flavorant (p>0.05). However, color acceptance scores of fish balls added with the TD flavorants were lower than those of other methods (p<0.05). The fish balls added with SD20, SD15+5M and TD15+5M had the highest overall acceptance score (p<0.05). Descriptive analysis revealed that the flavorant before drying had the highest intensity of roasted sundried shrimp, boiled sundried shrimp, boiled blue swimming crab and unfresh shrimp juice odors (p<0.05). The intensities of those odors decreased after drying the sample in all conditions. Mungoong (shrimp paste) odor was presented in tray dried sample and the highest intensity was found in tray dried sample with maltodextrin. The storage at room temperature (28±2°C) for 2 and 4 months under vacuum condition had less effect on the volatile compounds in shrimp flavorant than that under air condition. However, the trained panelists could not detected the differences between the intensities of odor characteristics (p>0.05). To produce a natural colorant from Pacific white shrimp (Litopenaeus vanamei) head, the optimized mixture proportions of isopropanol and hexane for carotenoid extraction was studied by applying the simplex lattice design. The prediction model showed that the proportion gaining the highest carotenoid yield was 40.731: 59.269 (v/v). The colorant extracted from pretreated shrimp head had the higher carotenoid yield, protein and ash content than that from non-pretreated shrimp head (p<0.05). However, moisture and fat content of both samples were not different (p>0.05). The studies of applications of flavorant and colorant extracted from Pacific white shrimp head in foods were conducted. Central composite design was used to optimize the concentration of shrimp flavorant (0-3% w/w) and colorant (0-0.4% w/w) in shrimp shumai. It was noticeable that the shrimp flavorant decreased liking scores of color, flavor, texture and overall (p<0.05), while color liking score was increased with the shrimp colorant added (p<0.05). Shrimp shumai added with 0.2% colorant had the highest color liking score (7.63 ± 0.89) when compared with that without the colorant (6.73 ± 1.20) and added at 0.4% (7.07 ± 0.60) (p<0.05). Another application, the shrimp colorant was applied to enhance color of mayonnaise-based dipping sauce. The colorant (NC: 0, MC: 1.2 and HC: 3.6%, w/w) and salts (RS: NaCl, ReS: KCl and NS: no salt added) were added to mayonnaise-based dipping sauce and the results showed that when colorant concentration increased the saltiness liking score decreased (p<0.05). Too intense color (HC) affected the decreasing of color liking score (p<0.05). The samples with the higher color liking scores gained the higher percentage to be just-about-right samples for expected saltiness. At the given colorant concentration, the highest saltiness liking score was occurred in RS followed by ReS and NS, respectively (p<0.05). Scores of emotions elicited by dipping sauces were highly affected by colorant concentration. Statements of 'colorant from a natural source' and 'sodium content' had a few effects on elicited emotions and consumer's purchase intent.