In this study, the potential of industrial celery by-products (the stalk and root) serving as sources of aromatics and antioxidants was investigated. A headspace solid phase microextraction–gas chromatography–mass spectrometry (HS-SPME–GC–MS) procedure was optimized to isolate volatile compounds from celery by-products. A Box–Behnken experimental design was proposed to optimize the procedure through a response surface methodology. The optimal extraction conditions were found to be 1.6 g of homogenized fresh by-product at 30 °C for 60 min. Under these conditions, 26 volatile compounds in stalk and root samples were identified, monoterpenes and sesquiterpenes being the main components. The content of limonene and γ-terpinene found in the stalk was significantly higher in comparison with root samples. Total phenolic content and antioxidant activity (ABTS and FRAP) results underlined the celery wastes studied as good sources of free radical scavengers. This work suggests the potential application of these by-products in the food industry and opens new pathways to valorize celery residues, contributing to the circular economy.

Pineapple is meanly commercially processed. However, it is a fruit that generates a high proportion of nonedible wastes, which are rich in antioxidant compounds and have a varied aromatic profile. These characteristics turn these by-products into potential agri-food waste that can be revalued and applied in different fields such as medical, pharmaceutical, or food applications. The aim of the present work was the characterization and extraction of the volatile compounds present in two pineapple by-products (peel and core) and the subsequent evaluation of their antioxidant capacity. For this purpose, the analysis of the aromatic profile of both by-products has been carried out using the headspace solid-phase microextraction technique coupled to gas chromatography with a mass spectrometry detector (HS-SPME-GC-MS). The optimization of the extraction conditions of the volatile compounds has been validated using a Box–Behnken experimental design. In addition, a quantitative analysis was carried out to determine the contents of two important volatiles in pineapple wastes, isopentyl, and ethyl acetate. Moreover, the estimation of the antioxidant capacity of the subproducts extracts was carried out using different methods All the antioxidant assays demonstrated that pineapple subproducts are rich in easily extractable antioxidants with possible applications in the food industry.