リンゴ

Reflection and absorption spectra of rinded apple slices in a visible range of wave length were estimated using a Shimadzu multipurpose recording spectrophotometer MPS-50, by which both the spectra can be estimated on the same sample-slice without attachment. As illustrated principles in Figs. 1 and 2, the MPS-50 has better sensitivity and precision than any other reflectometers of integrating sphere type or commonly used spectrophotometers. Therefore, the MPS-50 provides distinct spectra not only of transparent samples but also of translucent and opaque samples which hitherto had been considered immeasurable, if the relevant unique attachment had not been employed. As shown in Fig. 3, the reflection spectrum is principally identical with the absorption spectrum of the same slice. They have 4 peaks at 425～430 mμ (A), 450～455 mμ (B), 480～490 mμ (C) and 680 mμ (D), although relative values of reflex attenuance or absorbance of peaks var with species, "Kokko" and "Kogyoku." When an apple is rinded and left in the atmosphere, color of its surface turns to brown, while inner part of the apple is kept yellowish color. Fig. 4 indicated that the peaks A, B and C of the spectrum of the brown surface-slice was vague and relative values of reflex attenuance or absorption at B and C to that at A were lower than those of the control non-colored inner-slice. However, these features in the spectrum could not be observed, when browning of rinded apple had been prohibited by immersing it into a 0. 002M solution of sodium sulfite or cysteine of pH 6.5 for 10 minutes, as indicated in Figs. 5 and 6, whereas variation of the spectrum as well as browning of the surface of apple were seen in case of methionine as shown in Fig. 7. In order to establish these phenomena more decisively, the spectra were estimated with higher sensitivity after enlarging the range of absorbance 5 times from the ordinary "0～1.0" to "0～0.2." Of course, Fig. 8 gave the coincident result with those in Figs. 4～7. Finally variation of the spectra was quantitatively estimated at different time during progress of browning of the apple. In Fig. 9, the decrease in the relative values of the peaks B and C to that of A was confirmed by determining the spectra at 30, 60 and 120 minutes where the value of A had been settled constant. As evident in Figs. 10 and 13, the base line of the spectra were incidentally elevated with time over the visible range of wave length estimated, when the browning of the apple has proceeded. On the contrary, Figs. 11 and 12 indicated that a notable enhancement of the reflex attenuance had not been observed on the non-colored apple treated with sodium sulfite or cysteine to inhibit the browning.