Quality preservation of walnut kernels using edible coatings

Abstract

The objective of this work was to evaluate the performance of various edible coatings for preserving the quality of walnut kernels (W) during storage. Three edible coatings based on carboxymethyl cellulose (CMC), methyl cellulose (MC) and whey protein isolates (WP) were prepared. Coated and uncoated walnuts (WC) were stored for 210 days at room temperature (23±2 °C). After 210 days, WC presented the highest peroxide value (PV = 3.06 meqO2/kg), conjugated dienes (CD = 3.01) and trienes (CT = 0.31), pentanal, nonanal, hexanal, and decane, 5,6-bis (2,2-dimethylpropylidene) contents. Meanwhile, WMC showed the lowest PV (1.20 meqO2/kg), CD (2.26) and CT (0.17) and the lowest decrease in carotenoid content (0.60 mg/kg). The L* value measured in walnut oil decreased in all samples. MC, CMC and WP coatings showed protection on walnuts against the deterioration process. MC coating displayed the best performance. RESUMEN: Conservación de la calidad de los granos de nueces utilizando recubrimientos comestibles. El objetivo de este trabajo fue evaluar el comportamiento de cubiertas comestibles para preservar la calidad de nueces (W). Tres tipos de cubiertas fueron estudiadas: carboximetilcelulosa (CMC), metilcelulosa (MC) y aislados proteicos de suero de leche (WP). Las nueces con y sin cobertura (WC) fueron almacenadas durante 210 días a temperatura ambiente (23 ± 2 °C). WC presentó los valores más altos para indicadores químicos de oxidación lipídica (índice de peróxidos (PV) = 3,06 meqO 2 /kg; dienos conjugados (CD) = 3,01 y trienos conjugados (CT) = 0,31) y para volátiles de oxidación (pentanal, nonanal, hexanal y decane,5,6-bis(2,2-dimethylpropylidene). Por el contrario, WMC presentó los menores PV (1,20 meqO2/kg), CD (2,26) y CT (0,17) y la menor desaparición de carotenoides (0,60 mg/kg). El valor L* medido en el aceite de nuez decreció en todos los tratamientos. Las cubiertas comestibles MC, CMC y WP exhibieron efecto protector en el deterioro de las nueces. MC fue la que presentó mejor comportamiento.ORCID ID: Grosso AL https://orcid.org/0000-0003-3174-5745, Asensio CM https://orcid.org/0000-0003-0744-9188, Nepote V https://orcid.org/0000-0002-0615-5316, Grosso NR https://orcid.org/0000-0002-1709-9671 Citation/Cómo citar este artículo: Grosso AL, Asensio CM, Nepote V, Grosso NR. 2018. Quality preservation of walnut kernels using edible coatings. Grasas Aceites 69 (4), e281. https://doi.

A Natural Peanut Edible Coating Enhances the Chemical and Sensory Stability of Roasted Peanuts

“…It is interesting to note that ECs contributed to hinder the intensity rating increase of this attribute. Grosso, Asensio, Nepote, and Grosso () also detected higher and lower astringency increments for uncoated walnuts and for coated walnuts with methyl cellulose, respectively. In contrast, Zhao and McDaniel () mentioned that certain ECs made from chitosan could increase the intensity of astringency in coated samples.…”

“…The high‐protein content in the coating material was responsible for improving the coated peanut preservation (Grosso, Asensio, Nepote, & Grosso, , ). The method of DPF production led to a protein and carbohydrate content of 53.22g/100 g and 23.90 g/100 g, respectively (Riveros et al., ).…”

Improving walnuts’ preservation by using walnut phenolic extracts as natural antioxidants through a walnut protein‐based edible coating

“…Chromatographic responses of detected volatile compounds (peak area electronic counts: e.c.) were reported as a quantitative magnitude that indicates the evolution of the compounds in the different treatments during the storage study (Grosso, Asensio, Nepote, and Grosso, 2018a) and for those volatile compounds with a calibration curve, the quantification was also reported (µg/g).…”

In a nutshell: prospects and challenges on coatings for edible kernels

“…Several coatings have been proven effective to extend nut stability because of their inherent physical barrier (i.e. passive) properties . Although the presence of antioxidants is expected to add an active role to coatings, some studies revealed that their presence did not enhance coating performance.…”

“…passive) properties. 11,30,31 Although the presence of antioxidants is expected to add an active role to coatings, some studies revealed that their presence did not enhance coating performance. For instance, peanut oxidation was reduced by whey protein isolate coatings, but ascorbic palmitate and -tocopherol did not improve coating effectiveness.…”