Advances in drying techniques for retention of antioxidants in agro produces

Abstract

Antioxidants are compounds that are essential for the human body which prevents cell from disease causing free radicals. Antioxidants are present in a wide range of fruits, vegetables, and spices. However, a considerable amount of antioxidants is lost during the post-harvest drying operation of agro produces for their shelf-life enhancement. Hence, retention of antioxidants becomes utmost importance in preserving the nutritional aspects of fruits and vegetables. Compared to conventional hot air drying, methods like freeze drying, vacuum drying, and dehumidified drying helps in the retention of antioxidants. However, the drawbacks prevalent in current drying practices, such as high-power consumption and high capital cost, could be eliminated by adopting novel drying mechanisms. This review focuses on various pretreatment methods like ultra-sonication, high pressure processing, pulsed electric field and ethanol treatment prior to drying operation helps in enhancing the drying efficiency with maximum retention of antioxidants. In addition, hybrid drying technologies such as microwave assisted drying, IR-radiated drying and electro-magnetic assisted drying methods also could significantly improve the retention of antioxidants.

HIGHLIGHTS

1. Drying is the most commonly adopted unit operation for enhancing the shelf life of perishable agro produces.

2. However, drying is accompanied by loss of bioactive, color, texture, and sensory attributes.

3. Compared to conventional drying techniques like hot air drying, methods like freeze drying, vacuum drying and dehumidified drying helps in the retention of antioxidants present in agro/food produces.

4. Pretreatment methods like Ozonation, ultra-sonication, and UV radiation prior to drying are also found to improve the drying performance with good retention of antioxidants.

5. Recent developments like microwave-assisted and IR-assisted drying methods perform well in the retention of antioxidants with less energy consumption.

Keywords:

• Shelf-life enhancement
• antioxidants
• dehumidified drying
• pretreatment
• hybrid drying

Acknowledgements

Corresponding author, Mr. Venkatesh T would like to express his sincere gratitude and thanks to his senior colleagues Dr. Reshma, Principal Scientist and Mr. Venugopal V V, Senior Principal Scientist for their constant motivation and support in his scientific career. Corresponding author also extends his thanks to Vasanth Anna for his proof-reading during revision.

Disclosure statement

No potential conflict of interest was reported by the authors.

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

Venkatesh Thulasiraman thanks Department of Science and Technology, Govt. of India for the funding [Sanction No.: SP/YO/2019/1496].