The valorization of industrial food byproducts by means of environment-friendly extraction methods is becoming a major interest because of its environmental and economic values. In this study, the efficiency of many technologies, such as ultrasounds (US), microwaves (MW), and infrared (IR), was compared, in terms of polyphenol yield and bioactivity from apricot pomace. IR was the most effective method with the highest polyphenol (10 mg GAE/g DM), flavonoid (6 mg CE/g DM), and tannin (3.6 mg/L) yields. In terms of efficacy, IR was followed by MW, US, then solid-liquid (S/L) extraction. IR extract from apricot pomace exhibited the highest inhibitory activity against all the studied gram-positive strains (Methicillin Resistant Staphylococcus aureus, Staphylococcus aureus, Methicillin-resistant Staphylococcus epidermidis, and Staphylococcus epidermidis) and a one gram-negative strain (Escherichia coli). Moreover, IR extracts had by far the highest antiradical activity (AC) (40%) followed by MW (31%), US (28%), and then S/L (15%). High-performance liquid chromatography (HPLC) permitted the identification and quantification of rutin in all extracts; whereas catechin was detected in those of IR (3.1 μg/g DM), MW (2.1 μg/g DM), and US (1.5 μg/g DM). Epicatechin was exclusively found in IR extract (4 μg/g DM), suggesting the selectivity of IR towards this compound. Scanning electron microscopy (SEM) revealed that the IR technique induced the highest cellular and structural damage in apricot pomace, which could explain the effectiveness of this technology.

The preservation of polyphenols in fruits by lyophilization has gained great interest in the recent decades. The present study aims to assess the impact of the pre-treatment extraction methods heat-assisted extraction (HAE) and infrared (IR) on lyophilized apricot pomace extracts. Then to test the conservation of polyphenols quantities as well as their bioactivities (antiradical and antibacterial) in lyophilized extract. An aqueous extract was obtained through either heat-assisted extraction or infrared pre-treatments then lyophilized to obtain a dried form. Results showed that the content of polyphenols, the antiradical and antibacterial activities in lyophilized extracts exhibited a slighter decrease in infrared sample compared to the heat-assisted extraction ones. The High-performance liquid chromatography (HPLC) analysis showed that lyophilized extracts IR and HAE preserved the same phenolic molecules (rutin, catechin and epicatechin) detected in liquid extracts (IR and HAE) with a smaller yield. Lyophilization can be used as a widely process in the food industry to conserve many bioactive molecules.