Bio-based films prepared with apple pomace: volatile compound composition, antioxidant and antimicrobial activities

The valorization of agro-industrial by-products can be used as an alternative means for the production of healthy food ingredients and material. In the present study, the evaluation of the volatile profile by headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC/MS), antioxidant and antimicrobial activities of apple pomace (AP) and biodegradable cassava starch plastic film extruded with addition of apple pomace (4% and 8%) were carried out. Fifty-seven volatile compounds were detected in the samples. Out of the many compounds detected, 44 were present in the AP and 35 in the APF 4% and AFP 8%. The major classes of compounds in the samples were aldehydes (13) and esters (13). In fact, the nonanal (4.5%) followed by hexanal (3.21%) and benzaldehyde (1.99%) were the most abundant compounds. Ethylphenyl propanoate and hexyl hexanoate were the most abundant ester in the AP. However, adipic acid cyclic tetramethylene ester and hexanal were the most abundant volatile compounds in the films. In adittion, five terpenoids were abundant in the AP, representing 23.65% of the volatiles in this sample. The total phenolic compounds content by Folin–Ciocalteu method of AP, APF4% and APF8% were 2.04, 0.51 and 0.70 mg gallic acid/g, respectively. The DPPH radical scavenging antioxidant activity values were 4.26, 0.23 and 0.33 µmol Trolox/g for AP, APF4% and APF8% respectively. The minimum inhibitory concentration against Staphylococcus aureus, Salmonella thyphimurium and Escherichia coli for all samples tested was greater than 12.50 mg/mL. In this study, combined techniques of HS-SPME and GC-MS allowed the determination of the fingerprint of apple pomace and apple pomace film volatile components. Higher concentrations of the same extracts mat be required to exhibit significant antimicrobial properties. However, the apple pomace due its antioxidant activity could have real potential use as a functional ingredient in biodegradable packaging.