抄録
One of the present authors previously proposed the use of reflectance constant (KR) as an indication of the rate of browning7).
In the present work, the possibilities of the use of KR was examined in detail. The results may be summerized as follows. Reflectance and KR were obtained with flounder flesh to which various amounts of caramel were added (Table 1). KR value linearly correlated with the concentration of caramel (Fig. 2), while reflectance at 500mμ correlated with logarithm of the concentration of caramel (Fig. 1). From these, it is considered that the use of KR value is appropriate to express the rate of browning caused by amino-sugar reaction. Another advantage of the use of KR was to eliminate the variation of reflectance due to species of fish (Fig. 3 and Table 2). Slight browning was observed on the flounder flesh with KR of 2.5, and heavy with 3.0. Autoclaving of the flounder flesh below 115°C for 1 hour did not cause intense browning (Fig. 4).
The degree of browning varied among flesh from different parts of body or with different freshness (Table 3). At fresh stage, caudal muscles of most species tested showed a trend to be browned by autoclaving, while dorsal muscles of some species such as seabass browned strongly after storage. In the previous paper8), it was shown that the caudal muscle of fresh seabasc contained greater amounts of hexose compounds than other parts, while the dorsal muscle contained greater amounts of pentose compounds. These facts suggest that hexose seems to be a limiting factor in the browning of fresh flesh, whereas pentose to be liberated from pentose compounds during storage plays an important role in the browning of stored or spoiled flesh, as postulated by JONES12).
