ABSTRACT Tannins are a class of phenolic compounds commonly found in plants and studied for their bioactive properties. Acorn contains considerable amounts of tannins which have undesired astringent properties and bitter taste when consumed. The present study aimed to reduce tannin content in acorn fruits to improve their sensory quality and promote their use in food applications. Tannin extraction was carried out using two treatments, soaking treatment and roasting treatment, and optimized using Response Surface Methodology (RSM). The obtained acorn flours were evaluated for their biochemical composition, techno-functional properties, storage stability and cytotoxicity on Vero cells. Results revealed that tannin content in acorn flours was significantly reduced by 41.22% and 73.24% following roasting and soaking treatments, respectively. Both treatments led to lower fat and protein contents compared to raw acorn flour. The highest total polyphenol and flavonoid contents were observed in acorn flours obtained by soaking and roasting treatments, respectively. Functional properties showed that acorn flour obtained by soaking exhibited the highest water absorption capacity (0.26 g/g) and swelling index (3.87 mL/g). In terms of storage stability, acorn flour produced by roasting treatment showed the lowest water activity (0.16) and moisture content (11.2%). Cytotoxicity assays indicated low toxicity of the treated acorn flours. The studied treatments effectively reduced tannin content while improving functional and stability properties without inducing cytotoxic effects of obtained flours. These findings highlight the potential of treated acorn flour as safe and functional ingredients for food applications, particularly in gluten-free formulations.
Zarroug et al. (Fri,) studied this question.