# Efficacy of Herbal Extracts-Based Nano-Formulations in Extending Guava Fruit Shelf-Life
## 4 Discussion
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Coating** & \multicolumn{2}{c}{**Effect of Coatings**} & **Deposition** & **References** \\ \hline Gum Arabic and Moringa extract & Sustained fruit firmness, TSS, antioxidant activity and total sugars & Dipping & [26] \\ \hline Arabic Gum, Sodium Caseinate and Tulsi Extract & Reduced evaporation, transpiration and oxygen transmission & Dipping & [25] \\ \hline Gum Arabic and Cinnamon Essential Oil & Reduced PLW, maintenance of firmness, carotenoid content, and chlorophyll content, as compared to control fruit & Dipping & [11] \\ \hline Chitosan and Ruta Gravelopens Essential Oil & Antimicrobial activity against _Colletotrich_ _glosperorioides_ and maintenance of fruit firmness; lesser PLW & Dipping & [27] \\ \hline Agar (4\%) + Pomegranate Seed oil (0.4 mL/L) & Reduction in PLW; fruit color and TSS maintained by coating and no change in carotenoid content & Dipping & [28] \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Effect on edible coatings on shelf life of guava. which shriveled on the 7 th day (approx. 70%). Uncoated fruits' premature ripening leads to tissue damage which makes them more prone to microbial attack. Similar results were observed for tomato fruit treated with starch coating [34]. Figure 6 shows the change in firmness of guava fruits after the application of T1, T2 and T3 NFs during storage, which ranges from 4.47 to 8.41 kg/cm\({}^{2}\) and 4.84 to 8.37 kg/cm\({}^{2}\) during storage at 25 \(\pm\) 2 \({}^{\circ}\)C and 32 \(\pm\) 2 \({}^{\circ}\)C, respectively. Maximum decrease in firmness was observed in control fruits (uncoated) followed by T1, T3 and T2 coated guava fruits at both temperature storage conditions. One reason behind firmness loss is the action of hydrolytic enzymes such as \(\beta\)-D-glucosidase hydrolysis of pectin in guava [35]. Uncoated fruits lose moisture and become inflexible in sustaining firmness compared to NFs treated fruits. NFs have a binding capacity and regulate moisture and gaseous exchange; this maintains fruit firmness. [PERSON] et al. [36] observed similar results in guava fruits coated with zein protein and tannic acid. Coating of 'Rocha' pears with nano-emulsions of sodium alginate with citral and lemongrass essential oil preserved the firmness of fruit for a longer time compared to control fruit [37]. In the present study, the results showed that the color of guava fruits varied, turning yellow in all the treated as well as control fruits. In control fruits, the color changed to the yellow stage at the 4 th DAT and at the 6 th DAT at 32 \(\pm\) 2 \({}^{\circ}\)C and 25 \(\pm\) 2 \({}^{\circ}\)C, respectively. The prepared NFs delayed the change in color in all the treatments under both storage conditions. T2 showed most prominent results where color change was delayed, and the yellow stage appeared on the 6 th and 8 th DAT at 32 \(\pm\) 2 \({}^{\circ}\)C and 25 \(\pm\) 2 \({}^{\circ}\)C, respectively, as compared to control fruits which attained the yellow colored stage on the 4 th and 6 th DAT (Figures 7 and 8). The color change in fruits from green to yellow is ascribed to pigment content changes such as decrease in chlorophyll and increase in carotenoid content during storage. A 400% increase in carotenoids and 72% decrease in chlorophyll content was observed in plume guava stored at 27 \({}^{\circ}\)C and resulted in color change from green to yellow [38]. Moreover, the color change is affected by the action of polyphenol oxidase in the presence of oxygen which causes a browning reaction in fruits [39]. Coating of 'Rocha' pears with nano-emulsions of sodium alginate with citral and lemongrass essential oil reduced color change development as compared to uncoated control fruits [37]. Application of edible coatings replaces the O\({}_{2}\) and releases CO\({}_{2}\) which slows down the oxidation of fruits which in turn cause lesser ethylene production. Water loss from the fruit surface is also minimized which results into higher firmness and shelf life of guava.