Xanthan gum coatings augmented with lemongrass oil preserve postharvest quality and antioxidant defence system of Kinnow fruit under low-temperature storage

Comparative efficacy of chitosan-HPMC-based nanoencapsulation and ultrasonic treatment of thymol-cinnamaldehyde for controlling Rhizopus stolonifer in papaya: In vitro and in vivo studies

This study examines the in vitro antifungal properties and in vivo efficacy of thymol-cinnamaldehyde (TH-CIN) loaded nanocapsules, prepared using chitosan (CH) and hydroxypropyl methylcellulose (H) with varying ultrasonic power (200-600 W), for controlling Rhizopus stolonifer in papaya. Ultrasonic power notably influenced the nanocapsules' antifungal properties, both in vitro and in vivo. Higher ultrasonic power resulted in improved antifungal activity, with NC-CH-400 and NC-CH-H-600 formulations achieving the highest inhibition zones (94.67 % and 93.33 %, respectively) against R. stolonifer in vitro. The Minimum Inhibitory Concentration (MIC) for CH formulations was 6.25 mg/mL, while the Minimum Fungicidal Concentration (MFC) for all formulations was 50 mg/mL. Protein leakage assays demonstrated significant disruption of R. stolonifer cell membranes, with NC-CH-400 and NC-CH-H-600 at MFC reducing intracellular protein concentrations by over 95 %. In vivo tests showed that NC-CH-400 nanocapsule-coated papayas, whether sprayed or dipped, reduced weight loss to 0.54 % and 0.86 %, respectively, and exhibited lower decay severity indices, particularly during storage. Spraying was more effective than dipping in preventing decay. Peel color analysis revealed that coated fruits maintained acceptable ripeness levels over 10 days, indicating delayed maturation. Coated fruits also exhibited better color consistency and were preferred in sensory evaluations for improved taste, aroma, color, and texture, particularly with NC-CH-400 and NC-CH-H-600 coatings.

Combined application of hot water and hexanal-based formulations preserves the postharvest quality of mango fruits

BACKGROUND

Mango fruits undergo numerous postharvest quality losses during storage. Hence, the present study aimed to increase the shelf life of mango fruits by applying hexanal-based enhanced freshness formulations (EFF) in combination with hot water treatment (HWT).

RESULTS

The findings revealed that, among all the tested applications, the combination of EFF 1.0% + HWT reduced the weight loss, decay incidence, and activity of cell wall degrading enzymes of mango fruits. Also, the combined treatment was effective in maintaining the fruit quality parameters such as soluble solid contents, titratable acidity, ascorbic acid and activity of antioxidant compounds.

CONCLUSION

The present study concludes that the postharvest application of EEF 1.0% in combination with HWT can be used in extending the shelf life of mango cv. 'Langra,' fruits stored at 12° C and 85-90% relative humidity for 35 days. © 2024 Society of Chemical Industry.

Enhancing Mexican lime (Citrus aurantifolia cv.) shelf life with innovative edible coatings: xanthan gum edible coating enriched with Spirulina platensis and pomegranate seed oils

BACKGROUND

The Mexican lime (Citrus aurantifolia cv.), widely consumed in Iran and globally, is known for its high perishability. Edible coatings have emerged as a popular method to extend the shelf life of fruits, with xanthan gum-based coatings being particularly favored for their environmental benefits. This study aims to evaluate the effectiveness of an edible coating formulated from xanthan gum, enriched with Spirulina platensis (Sp) and pomegranate seed oil (PSO), in improving the quality and reducing the weight loss of Mexican lime fruit under conditions of 20 ± 2 °C and 50-60% relative humidity.

RESULTS

Based on the results, the application of coatings was generally effective in reducing fruit weight loss, with the least weight loss observed in the xanthan gum 0.2%+ Spirulina platensis extract (1%) treatment. Additionally, the levels of total phenols and flavonoids in the treated fruits exceeded those in the control group, with xanthan gum 0.2%+ Spirulina platensis extract (1%) and xanthan gum 0.2% exhibiting the highest concentrations of these compounds. The antioxidant capacity of the fruits was also enhanced by the coatings, surpassing that of the control group, with xanthan gum 0.2%+ Spirulina platensis extract (1%) achieving the highest levels. The treatments significantly suppressed the activity of the polyphenol oxidase (PPO) enzyme, with xanthan gum 0.2% demonstrating the most potent inhibitory effect. Furthermore, the treatments resulted in increased activities of catalase (CAT) and peroxidase (POD) enzymes compared to the control. Except for xanthan gum 0.2%+ pomegranate seed oil (0.05%), all treatments maintained the fruit's greenness (a*) more effectively than the control.

CONCLUSIONS

Peel browning is a major factor contributing to the decline in quality and shelf life of lime fruit. The application of 0.1% and 0.2% xanthan gum coatings, as well as a combination of 0.2% xanthan gum and Spirulina platensis extract, significantly inhibited PPO activity and enhanced the activity of CAT and POD and phenolic compound in Mexican lime fruits stored at of 20 ± 2 °C for 24 days. Consequently, these treatments comprehensively preserved lime fruit quality by significantly reducing browning, maintaining green color, and preserving internal quality parameters such as TA, thereby enhancing both visual appeal and overall fruit quality.

Application of hydroxypropyl methylcellulose to improve the wettability of chitosan coating and its preservation performance on tangerine fruits

Hydroxypropyl methylcellulose (HPMC) was employed as an intermediate layer to enhance interfacial interaction between chitosan (CS) coating and tangerine fruits, thereby improving the preservation effect. Owing to the low surface tension of tangerine fruit (26.04 mN/m), CS coating solutions showed poor wetting properties on fruit peels (contact angle > 100°). However, by applying a 1.0 % (w/v) HPMC coating on fruits, the contact angle of CS solutions with concentrations of 0.5 %, 1.0 %, and 1.5 % (w/v) decreased to 47.0°, 47.4°, and 48.5°, respectively, whereas the spreading coefficient increased to -16.0 mN/m, -17.6 mN/m and -19.8 mN/m, respectively. Subsequently, the effects of the coatings on fruit quality were investigated. The results demonstrated the promising performance of HPMC-CS two-layer coating in inhibiting fruit respiration, reducing decay rate, and maintaining nutrient content. Notably, HPMC-1.5%CS coating not only reduced the decay rate of tangerine fruit by 45 % and 31 %, in comparison to the uncoated group (CK) and pure CS coating respectively, but also maintained a high content of ascorbic acid. Therefore, this study confirmed that the use of amphiphilic polymers for improving the surface properties of fruits can effectively facilitate the wetting of hydrophilic coatings on fruits, and significantly improve the fresh-keeping performance of edible coatings.