Effect of methyl cellulose coating on physicochemical properties, porosity, and surface diameter of pistachio hull

Abstract

Pistachio is a nut with high consumption that can be affected by aflatoxin contamination. Regarding influence of this fungus on global trade, broad studies in this area seem to be necessary. In this research, pistachio nuts were coated with methyl cellulose at different concentrations of 0.1%, 0.5%, 1%, and 2% by immersion method. Samples were stored in an incubator (25°C) for 4 months. Imaging was performed by electron microscope using SEM method and chemical changes (moisture, iodine, peroxide, and acidic value) were investigated during storage periods. Results showed that variations in storage time and methyl cellulose concentration had significant effect on moisture content and peroxide value (P < 0.05). Also, in case of acidic value, a significant difference was observed between treatments so that pistachio at concentration of 2% showed the highest acidic value. The highest iodine value loss was related to a concentration of 0.1% and the lowest value was observed in the control sample.

Quality preservation of walnut kernels using edible coatings

“…Peroxide formation proceeds slowly in the initial stages of oxidation. However, in the later stages, it acts as a catalyst in oil oxidation (Moslehi et al, 2015). In this study, the PV increased for all walnut samples during the storage period.…”

“…Once more, MC acted as a barrier between walnuts and the atmosphere, preventing gas exchange and, as a consequence, lipid oxidation. This was previously studied in coated pistachios (Moslehi et al, 2015) and avocados (Maftoonazad and Ramaswamy, 2005) where MC coating lessened moisture losses and respiration rates. Other studies have also found lower values of CD in products protected with edible coatings.…”

“…Because of these factors, it can be assumed that methyl cellulose inhibits oxidation in the coated walnut kernels. Moslehi et al, (2015) found that pistachios coated with MC had the lowest PV after four months of storage, and Grosso et al, (2017) found that MC coating had a preserving effect in the intensity of the characteristic walnut flavor which reduced the development off-flavors related to lipid oxidation. In a different study, the maximum PV occurred in non-coated control samples; walnuts coated with chitosan and green tea extract had significantly (p < 0.05) lower PV value after 18 weeks of storage (Sabaghi et al, 2015).…”

Impact of carboxymethyl cellulose coating enriched with Thymus vulgaris L. extract on physicochemical, microbial, and sensorial properties of fresh hazelnut ( Corylus avellana L.) during storage

“…Extract, on the one hand, had an effect on reducing the moisture absorption of coating and, on the other hand, increased the shelf life of the nuts by decreasing the permeability of the coating to oxygen (Haq et al., 2013). These results were in agreement with others (Hashemi et al, 2020; Moslehi et al, 2015; Sabaghi et al., 2015), confirmed that a higher concentration of coating materials, extract, or essential oil decreases the peroxide value of nuts.…”

Effect of Moringa oleifera leaves extract on lipid peroxidation and sensory characteristics in cookies

“…However the rate of increase in diene content in later stages of heating is expected to be lower, finally reaching a plateau due to the establishment of equilibrium between the rates of formation of conjugated dienes to that of polymers [36]. Peroxide value (PV) is also used to determine the rate of lipid peroxidation especially during the initial stage [37]. Lipid hydroperoxide is one parameter that is commonly measured in lipids to determine their oxidation state; however, iodometric titration is one preferred method for the determination of lipid hydroperoxide level as peroxide value (PV).…”