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

Abstract

The 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 Applications Peanut 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.

Selected nutrients and antinutrients in peanut cultivars harvested in Brazil

“…Peanuts are major dietary sources of saponins, and contain phytates and condensed tannins. Despite their associated pharmaceutical properties, these substances may be antinutrient food components and their total content was determined by spectrophotometry (Table ).…”

“…Condensed tannins are polyphenols that impart color to the peanut testa and are present in the skin and in the cotyledon . These plant secondary metabolites can precipitate proteins and complex with Fe, impairing their bioavailability .…”

Bioavailability and Hypolipidemic Effects of Peanut Skin Polyphenols

“…Blanched peanut skin could be incorporated to up to 3.75% levels higher than roasted peanut skin without altering the physical properties of the peanut butter. 32 The potential of peanut skin polyphenols, by extracting procyanidins in a hot-water infusion and concentrating and spray drying for potential use as a food ingredient and an antioxidant-rich beverage, has also been studied. 4 In this study, peanut skins were extracted with 70% ethanol.…”

“…32 Studies have also been undertaken to show the effect of processing, such as spray drying on the antioxidant capacity, total phenolics of peanut skins. 4 Future studies with the oligomeric procyanidins from peanut skin extract will aid in broadening our understanding in how these compounds are metabolized.…”

Desenvolvimento e caracterização de matrizes poliméricas como veículo de componentes ativos do extrato etanólico da película de amendoim

“…Potencialmente, o extrato de pele de amendoim in natura ou seco além de ser uma fonte de polifenóis, pode evitar a oxidação em alimentos substituindo o uso de antioxidantes sintéticos (Constanza et al, 2012). Ma et al (2013) avaliaram o efeito da incorporação da película de amendoim moída na formulação de manteiga de amendoim visando a fortificação das mesma em função da presença de procianidinas naturais da película e verificaram que a incorporação de até 3,75% (m/m) de película de amendoim (obtida amento) provocou aumento da concentração de fenólicos em até 533%, embora tenham sido observadas algumas variações nas propriedades físicas da manteiga de amendoim. Yu et al (2010) verificaram que o extrato de película de amendoim foi capaz de conservar a cor da carne moída crua e impedir a oxidação lipídica na carne moída cozida durante seu armazenamento sob refrigeração, sendo que a adição de concentrações iguais ou superiores à 0,06% de extrato apresentou eficiência equivalente ao butilhidroxianisol/butil hidroxitolueno (BHA/BHT) à concentração de 0,02% na inibição da oxidação de lípidos.…”