J Food Bioact

Journal of Food Bioactives, ISSN 2637-8752 print, 2637-8779 online

Journal website www.isnff-jfb.com

Original Research

Volume 25, March 2024, pages 52-61

Fuji apple (Malus domestica Borkh. cv. Red Fuji) pomace extracts as a source of antimicrobial and antioxidant polyphenols

Figures

Figure 1. The Effect of PPE and CPE on the growth curves of S. aureus during 12 h of incubation. (a) S. aureus was treated with PPE; (b) S. aureus was treated with CPE.

Figure 2. Halos (clear zones) of inhibition of growth of S. aureus formed around colonies of PPE and CPE on LB agar. (a) circle filter papers treated with PPE; (b) circle filter papers treated with CPE; Control: the control group.

Figure 3. Scanning electron microscope (SEM) images at 30.0 K × and 50.0 K × magnification showing morphological changes of S. aureus treated with PPE or CPE.

Figure 4. Antioxidant activity of PPE and CPE in ABTS radical scavenging test as compared with L-ascorbic acid. Different letters marked in the same concentration indicate significant differences (p < 0.05) between any two groups.

Figure 5. Antioxidant activity of PPE and CPE in FRAP test as compared with L-ascorbic acid. Different letters marked in the same concentration indicate significant differences (p < 0.05) between any two groups.

Tables

**Table 1.** The diameters of Inhibition zone of PPE and CPE against *S. aureus* on LB agar
Groups	Diameter of inhibition zone (mm)	Assessment of inhibitory effect
ND: not detected; –: no inhibitory effect (diameter of inhibition zone ≤7 mm); +: positive inhibition inhibitory effect (diameter of inhibition zone >7 mm).
Control	ND	–
PPE	11.15 ± 0.39	+
CPE	6.20 ± 0.14	–

**Table 2.** The minimum bactericidal concentrations (mg/mL) of PPE and CPE against *S. aureus*
Bacterium	Polyphenol extracts	Growth of bacteria
		The concentration of the polyphenols (mg/mL)
		1.56	3.13	6.25	12.50	25
Note: –: aseptic growth; +: small amounts of bacteria growth (colony number ≤5); ++: mass bacterial growth (colony number >5).
*S. aureus*	PPE	++	+	+	+	–
*S. aureus*	CPE	++	++	++	++	++

**Table 3.** Bacteriostatic effects of PPE and CPE against *S. aureus* in simulated starch-based food matrices
Groups	Diameter of inhibition zone (mm)
	Concentration of corn starch (w/v)
	0%	1%	2%	3%	4%	5%
Note: –: no inhibition (diameter of inhibition zone ≤9 mm); same letters indicate no significant difference (p > 0.05).
PPE	11.06 ± 0.60^a	11.28 ± 0.24^a	11.24 ± 0.34^a	11.86 ± 0.26^a	11.88 ± 0.28^a	11.74 ± 0.16^a
CPE	–	–	–	–	–	–
Control	–	–	–	–	–	–