Comparison of the Total Phenolic and Ascorbic Acid Content of Freeze-Dried and Air-Dried Marionberry, Strawberry, and Corn Grown Using Conventional, Organic, and Sustainable Agricultural Practices

TLDR

Secondary phenolic metabolites are key in plant defense and human health, yet few studies have examined how different agricultural practices affect their levels. The study measured total phenolic content in marionberries, strawberries, and corn grown under sustainable, organic, or conventional practices and evaluated the impact of freezing, freeze‑drying, and air‑drying on these levels. TP was quantified in the three crops across the three cultural practices, and the effects of the three postharvest treatments on TP content were assessed. Organically and sustainably grown foods consistently showed higher TP levels than conventionally grown ones, and freeze‑drying preserved more TPs than air‑drying in all samples. Keywords: phenolics, ascorbic acid, sustainable agriculture, organic agriculture, conventional agriculture, strawberry, corn, marionberry.

Abstract

Secondary phenolic metabolites play an important role in plant defense mechanisms, and increasing evidence indicates that many are important in human health. To date, few studies have investigated the impact of various agricultural practices on levels of secondary plant metabolites. To address this issue, the total phenolic (TP) content of marionberries, strawberries, and corn grown by sustainable, organic, or conventional cultural practices were measured. Additionally, the effects of three common postharvest processing treatments (freezing, freeze-drying, and air-drying) on the TP content of these agricultural products were also investigated. Statistically higher levels of TPs were consistently found in organically and sustainably grown foods as compared to those produced by conventional agricultural practices. In all samples, freeze-drying preserved higher levels of TPs in comparison with air-drying. Keywords: Phenolics; ascorbic acid; sustainable agriculture; organic agriculture; conventional agriculture; strawberry; corn; marionberry