Assessment of the In Vitro Glycemic Index, Content of Bioactive Compounds, and Their In Vitro Bioaccessibility in White Bread Enriched With Pinus nigra Ten. Bark Extract

Abstract

Pinus nigra Ten. (black pine) bark, a by-product of the timber industry, is rich in bioactive compounds with high antioxidant activity and various health benefits. This study investigated the effects of the addition of pine bark extract (PBE) into bread at different concentrations (0%, 0.25%, 0.50%, and 1.00%; w/w) on the hydrolysis index (HI), predicted glycemic index (pGI), antioxidant activity (DPPH and FRAP), total phenolic content (TPC), in vitro phenolic digestibility, mineral composition, textural properties, and sensory attributes. Bioaccessibility levels of the control bread were 6.79% for TPC, 8.99% for FRAP activity, and 6.44% for DPPH radical scavenging activity, whereas 1.00% PBE-enriched bread exhibited significantly higher values of 28.63%, 30.14%, and 22.75%, respectively. Incorporation of 0.50% and 1.00% of PBE into bread also reduced their pGI significantly; thereby these breads were classified as medium (pGI = 66.28 and 59.29, respectively) glycemic index. A strong linear correlation was observed between TPC and antioxidant activities. Mineral analysis (mg/100 g) confirmed the presence of essential macro- (Ca [19.79-38.95], K [4.80-25.72], Mg [5.78-12.38], Na [7.12-28.29]) and microelements (Zn [2.62-3.61], Cu [< 2.5], Fe [< 2.5], Mn [< 2.5]) in especially PBE-enriched breads. Texture analysis showed that the breads became softer (304.43-394.09 N) in proportion to the PBE level while sensory evaluations did not show any negative effect of PBE addition. Overall, these findings highlighted the potential of PBE as a valuable functional ingredient for enhancing the nutritional and technological properties of bakery products.