Effect of Peanut Skin Incorporation on the Color, Texture and Total Phenolics Content of Peanut Butters

Abstract

AbstractThe impact of incorporating ground dry‐blanched or roasted peanut skins (PS, three types: light‐, medium‐ and dark‐roasted) into peanut butter as a functional food ingredient was examined. A desirable grind size for the PS of less than 300 μm was achieved in most cases by milling the skins with the sugar. Adding ground PS to peanut butter at 1.25, 2.5, 3.75 and 5.0% (w/w) resulted in a concentration‐dependent change in the Commission Internationale de l'Éclairage L* C* h values. Peanut butters formulated with medium‐ and dark‐roasted PS showed an increase in hardness, and were generally more adhesive than those without PS or with dry‐blanched PS. A marked change in spreadability was found with greater than 2.5% added PS. Incorporation of dry‐blanched PS, especially at levels below 3.75%, produced the fewest alterations in physical properties of the peanut butters compared with the control. Importantly, a concentration‐dependent increase in the total phenolics content (TPC) was evident with PS fortification. Dry‐blanched PS had a TPC of ∼166 mg (+)‐catechin equivalents/g extract and yielded peanut butters with a 32, 33 and 38% higher TPC than found with light‐, medium‐ and dark‐roasted skin incorporation, respectively. Correspondingly, dry‐blanched PS addition at 1.25, 2.5, 3.75 and 5.0% (w/w) resulted in an increase in the TPC by 86, 357, 533 and 714%, respectively, compared with peanut butters without PS fortification.Practical ApplicationsPeanut skins (PS) are a rich, inexpensive source of potentially health‐promoting compounds, notably proanthocyanidins. However, PS are not often utilized as a functional food ingredient in value‐added products. As the primary by‐product of the peanut industry, PS are usually discarded as waste with only a small amount used as animal feed. According to our study, ground PS incorporation into peanut butters effectively enhances the total phenolics content of the product and offers product line diversification while still retaining the product's standard of identity. Summarily, our research will aid the peanut industry via (1) by‐product/waste stream utilization; and (2) diversification of product lines by creating a value‐added peanut product with potential beneficial health properties.