Subcritical Water Treatment for Producing Seasoning From Semidried Isada Krill

Abstract

Semidried Isada krill (Euphausia pacifica) was treated with boiling water and subcritical water at 100-240C for 10 min with a semidried krill to a water ratio of 8/52 w/v to produce seasoning. The protein concentration, lipid content and odor concentration of the extract increased after increasing the treatment temperature. The highest protein content of the extract (0.047-0.049 kg/kg-extract) was obtained by subcritical water treatment at 180 or 200C. Compounds with lower molecular mass were detected in the extracts derived from subcritical water treatment at temperatures higher than 160C. The extract prepared by subcritical water treatment at 160 and 180C received the high score in the flavor preference test by a group of panelists. Treatment at temperatures lower and higher than 160-180C, respectively, conferred undesirable fishy and smoky or burnt odors to the extracts and residues. PRACTICAL APPLICATIONAlthough Isada krill is abundant in the Sanriku coast, Japan, its usage is limited to low-value-added products such as animal and aquaculture feeds. However, we found that subcritical water treatment of the krill produces an extract solution and a solid residue, both of which possess good flavor and proffer a great prospective for use as seasoning. Establishment of a method for using the krill as a raw material for seasoning with shrimp-like flavor would increase the value of the krill as a food resource for human consumption.

Direct Treatment of Isada Krill under Subcritical Water Conditions to Produce Seasoning with Shrimp-Like Flavor

“…The strongest shrimp-like fl avour was detected in the extracts and residues prepared at 140-160 °C. These results are similar to those for the treatment of raw krill mixed with water (10). The temperature dependence of preference scores was similar to that of the shrimp-like-fl avour intensity (Fig.…”

“…We have also applied the treatment to semi-dried or raw krill by mixing the krill with water at a mass ratio of 1:1, to produce extracts and residues having pleasant, shrimp-like fl avour (10,11). Using the products as seasoning should be safe regarding fl uoride toxicity because only a small amount will be applied to food products.…”

“…The treated krill was separated into liquid and solid residues by fi ltration under reduced pressure, followed by pressing as described previously (10). The liquid obtained from the solid residue by pressing was combined with the liquid extract from fi ltration.…”

Preparation of Liquid and Solid Seasonings with Shrimp-like Flavor from Isada Krill under Subcritical Water Conditions by Steam Injection

“…We also reported that treatment of the semi-dried and raw krill (Koomyart et al, 2015a(Koomyart et al, , 2015b under subcritical water conditions could produce liquid extracts and solid residues with a pleasant flavor, and may be prospective seasoning ingredients.…”

“…In the previous reports, we used a small pressure-resistant vessel with an inner volume of 117 mL, and the vessel was heated using either an external mantle heater or by immersion in an oil bath (Koomyart et al, 2015a(Koomyart et al, , 2015b. However, such heating methods would be inadequate or inconvenient for treating the krill in large quantities.…”