Low accumulation of chlorogenic acids represses reddening during flesh browning in Japanese peach “Okayama PEH7”

Figures & data

Fig. 1. Reduced browning phenotype in flesh homogenate of Okayama PEH7.

Notes: (A) Discoloration of homogenate prepared from fruit flesh of Okayama PEH7 and Okayama PEH8. Tubes on the left and right contain homogenates that were boiled or incubated at 25 °C for 2 h, respectively. (B) Browning potential of homogenate from Japanese peach cultivars. Browning potential is measured by changes in A_490nm during incubation at 25 °C for 1 h. Data are mean values ± standard error. Different letters above bars indicate significant differences at p < 0.01 (Tukey’s test).

Table 1. Color values of flesh homogenate prepared from Japanese peach cultivars.

Sample	Treatment	L	a	b
PEH7	Boiled	62.9^a	−0.1^c	8.3^b
PEH8	Boiled	59.2^a	−0.3^c	9.1^b
Hakuho	Boiled	64.0^a	0.4^c	8.1^b
Shimizu-hakuto	Boiled	63.0^a	0.2^c	8.5^b
PEH7	Incubated	62.8^a	2.3^c	19.1^a
PEH8	Incubated	49.4^b	10.9^a	21.3^a
Hakuho	Incubated	56.3^ab	7.3^ab	20.5^a
Shimizu-hakuto	Incubated	56.5^ab	6.9^b	21.5^a

Note: Means with different letters in the same column are significantly different at p < 0.05 (Tukey’s test).

Fig. 2. Comparison of phenolic compounds and PPO activity between Okayama PEH7 and Okayama PEH8.

Notes: (A) Levels of total soluble phenolic compounds in flesh. Phenolic compounds were expressed as gallic acid equivalents. Data are mean values ± standard error for six replicates. The asterisk indicates significant difference at p < 0.01 (t-test). (B) Relative PPO activity in flesh. Enzymatic activity was determined by changes in absorbance (A_490nm) using catechol as a substrate. Data are mean values ± standard error for six replicates. The asterisk indicates significant difference at p < 0.01 (t-test). (C) Substrate-enzyme substitution experiments. Supernatants of homogenates that were boiled or incubated at 25 °C for 2 h were supplied as substrates and crude extracts, respectively. They were mixed at a 9:1 ratio and incubated at 25 °C for 1 h, after which absorbance (A_490nm) was measured. Data are mean values ± standard error. Different letters above bars indicate significant differences at p < 0.01 (Tukey’s test).

Fig. 3. Analysis of phenolic compounds in fruit flesh.

Notes: (A) HPLC chromatogram of boiled flesh homogenates. (B) Levels of CGAs and flavonoids in flesh. Data are mean values ± standard error for six replicates. The asterisks indicate significant difference between Okayama PEH7 and Okayama PEH8 at p < 0.01 (t-test). (C) Effects of exogenous application of 5-CQA and PB1 on browning of PEH7 homogenate. 5-CQA was added to yield a final CGAs concentration of 227 μg/g FW. PB1 was added to yield a final flavonoid concentration of 163 μg/g FW. Different letters above bars indicate significant differences at p < 0.05 (Tukey’s test).

Table 2. Color values of flesh homogenate of Okayama PEH7 incubated with PB1 and 5-CQA.

Sample	Treatment	L*	a*	b*
PEH7	Incubated	62.8^a	2.3^b	19.1^a
PEH7	Incubated w/ PB1	60.0^a	4.0^b	21.4^a
PEH7	Incubated w/ 5-CQA	54.6^ab	8.0^a	20.7^a
PEH8	Incubated	49.4^b	10.9^a	21.3^a

Note: Means with different letters in the same column are significantly different at p < 0.05 (Tukey’s test).