A Modified Method for Hydrogen Peroxide Determination and Its Residual Content in Commercial Fish Jelly Products (“Kamaboko” and Related Kinds)

Abstract

Bleaching treatment of fish jelly products with hydrogen peroxide (H₂O₂) has been widely practiced after heat processing of these products. And, in addition, excessive uses of H₂O₂ by the industry frequently draws the attention of public health authorities and consequently raises an urgent need for survey of residual amounts of H₂O₂ in the products to control whether the treatments are adequately performed in the commercial preparations.
A modification of H₂O₂ determination method was firstly proposed in this paper, since a simple iodometry using sodium thiosulfate (Na₂S₂O₃) titration is apt to give some erroneous results in these particular products to which potassium hypobromide (KBrO₃) may have been added as a jelly texture improver.
Repeated experiments indicated that an use of catalase preparation to the aqueous extract of “Kamaboko” products before iodometric titration was found feasible to eliminate the effect of KBrO₃, where the titers of Na₃S₂O₃ represented only the concentration of hypobromide. Therefore, the difference in the titers between nontreated extract and catalasetreated one can be used as the basis of true H₂O₂ determination.
Most samples of “Kamaboko” and “Chikuwa” (baked bamboo-shaped products) purchased from Tokyo Central Fish Wholesale Market showed a small or negligible quantity of H₂O₂, except the samples manufactured in particular regions which contained considerable amounts of the chemical. “Hanpen” and “Naruto-maki” products examined revealed comparatively higher content of H₂O₂ and taste panels noted some off-flavour possibly due to the use of H₂O₂.
A sharp decrease of residual H₂O₂ was observed in the experimentally prepared “Kamaboko” during a storage period of several days after the bleaching treatment. The disappearance rate of H₂O₂ slackened thereafter for about ten days, when certain amounts of H₂O₂ still remained in the “Kamaboko”. And, higher residual content was noticed when either high H₂O₂ concentration or long time dipping in the bleaching solution was employed.
It was concluded from these examinations that a large amount of residual H₂O₂ in commercial fish jelly products should be attributed to the over-use of H₂O₂ and a reduced cocentration of H₂O₂ or shortened time of immersion in the bleaching solution was suggested.