Storage of Fruits and Vegetables in Refrigerator Increases their Phenolic Acids but Decreases the Total Phenolics, Anthocyanins and Vitamin C with Subsequent Loss of their Antioxidant Capacity.

Joseph H Y Galani,Jalpesh S Patel,Jayant G Talati,Nilesh J Patel

doi:10.3390/antiox6030059

Abstract

It is of paramount importance for consumers, scientists and industrialists to understand how low-temperature storage of food items affects their bioactive compounds and properties. This study evaluated the effects of cold storage on total phenolics (TP), phenolic acids profile (PA), total anthocyanins (TA), total ascorbic acid (Vit. C) and antioxidant activity (AA) of 19 fruits and vegetables, collected from local Indian markets and stored in refrigerator (4 °C) during 15 days. Content of TP was highest in dill and amaranth and decreased (up to 29.67%) with storage. Leafy vegetables (amaranth, dill, onion, fenugreek and spinach) contained higher amounts of the 12 PA revealed by UPLC-UV; ellagic, gallic, sinapic and vanillic acids levels were the highest; chlorogenic acid (ρ = 0.423), syringic acid (ρ = 0.403) and sinapic acid (ρ = 0.452) mostly correlated with TP; and the PA increased during storage. Highest contents of Vit C estimated by AOAC, DCPIP and DNP methods were found in amaranth, dill and pomegranate, and decreased with storage. Pomegranate showed highest TA levels and low-temperature storage did not significantly increase TA, which was the largest contributor of TP in fruits and vegetables (ρ = 0.661). Storage induced a drastic decrease of AA, which mostly correlated with TP (ρ = 0.808, 0.690 and 0.458 for DPPH, ABTS and FRAP assays, respectively). Spearman’s correlation confirmed by principal component analysis demonstrated that dill, pomegranate and amaranth had the highest overall antioxidant capacity, whereas orange juice and carrot showed the lowest. The results provide support for a key-role of TP, followed by Vit. C and TA in antioxidant capacity of fruits and vegetables, which could be interesting dietary sources of natural antioxidants for prevention of diseases caused by oxidative stress.

Highlights

Understanding the changes in phytonutrient content during postharvest handling of fruits and vegetables is important for both basic knowledge of postharvest physiology and for the food and health industries
total anthocyanins (TA) in antioxidant capacity of fruits and vegetables, which could be interesting dietary sources of natural antioxidants for prevention of diseases caused by oxidative stress
Storage of fruits and vegetables at 4 ◦ C during 15 days significantly decreased their total phenolics (TP) content, with the highest significant TP loss (29.67%) recorded in dill, an increase of TP was observed in amaranth, fenugreek, spinach, cabbage and apple, with up to 35.81% increase observed in amaranth (Figure 1)

Summary

Introduction

Understanding the changes in phytonutrient content during postharvest handling of fruits and vegetables is important for both basic knowledge of postharvest physiology and for the food and health industries. It is important for consumers and the larger audience to know the changes which occur in the nutritional quality and health-promoting compounds of the food they consume after storage in the household refrigerator. Beyond supplying energy and good quality proteins, fruits and vegetables are significant sources of phytonutrients such as antioxidants, which possess. Antioxidants derived from plant sources may play an important role in reducing the risk of degenerative diseases such as cancer, obesity, cardiovascular disease and diabetes [1]. Because many fruits and vegetables are highly perishable, after harvest, they are stored in cold conditions for many days before consumption

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