Summary

Compared to other berries, there is limited information on effective methods for preserving the freshness of blackcurrant (Ribes nigrum L.) after harvest. This study tested a control application (deionized water) against three treatments: 1) applying a natural coating called chitosan, 2) exposing the berries to ultraviolet (UV-A) light, and 3) combining both methods. The goal was to find out which treatments work best for keeping blackcurrants in good condition for fresh markets.

Why Chitosan and/or UV-A

Chitosan is a natural substance made from the exoskeletons of crustaceans like shrimp and crabs, as well as some fungi. It’s used in the industry as a safe, edible coating to help fruits and vegetables stay fresh longer by protecting them from spoilage and mold. Ultraviolet (UV) light is also sometimes used after harvest to help keep fruits and vegetables fresh. Stronger UV types (UVC and UVB) are often used to reduce microbial activity and boost color and nutrients in produce. UVA, a gentler type, has been less studied but can also help improve fruit quality, reduce spoilage, and keep flavors from fading during storage. Researchers were curious if a combination of the two treatments would have an additive effect.

Storage Conditions and Quality Monitoring

Blackcurrents were stored in plastic commercial clam shells in a walk-in cooler with 0°C-4°C 112 temperature, 85-90% humidity under the three different treatments and control for 15 days. The clam shells were each filled with about 70g of blackcurrants. Berries were monitored over the duration for physical appearance, weight, firmness, phytochemical properties, pH, sugar levels, and microbial populations.

Findings

Chitosan Treatment

  • Improved maintenance of berry weight
  • Lowered microbial populations
  • Improved berry firmness

UVA Light Treatment

  • Increased antioxidant levels, specifically cyanidin-3-galactoside (an anthocyanin) and rutin.
  • Did not significantly reduce mold or bacteria.

Other Notes

  • Combining chitosan + UVA offered no added benefits over using chitosan alone.
  • Antioxidant levels naturally decreased with storage time, regardless of treatment.
  • Treatments didn’t alter pH or acid content (key for flavor stability).

Recommendations

  • Prioritize chitosan if reducing spoilage and weight loss are critical.
  • Use UVA to enhance specific health-promoting compounds (marketing advantage).
  • Avoid combining treatments unless targeting both physical and chemical benefits separately.

Want more details?

Read the full research article.

 

Microbial populations in blackcurrants when exposed to three treatments and a control

Figure 3. Microbial population measurements on blackcurrants over 15 days of storage. Chitosan and Chitosan + UVA treatments significantly reduced yeast and mold growth compared to the control and UVA-only treatments. Although microbial counts increased over time for all groups, berries treated with chitosan (with or without UVA) had much lower levels even by day 15 than the control and UVA treated berries on day 0.

 

Suggested Visuals:

Weight Loss Comparison Chart

Line graph showing weight loss (%) over 15 days for chitosan-treated vs. UVA vs. control.

Anthocyanin & Phenolic Compound Diagram

Bar graph highlighting cyanidin-3-galactoside and rutin levels in UVA-treated berries.

Side-by-Side Berry Photos

Day 0 vs. Day 15 images of chitosan-treated vs. untreated berries to show firmness/decay.