Abstract

This experiment explored the effect of controlled atmosphere (CA) storage on the postharvest quality of raspberry fruit. Raspberries were stored at 5°C in 15% C02, 6% O2; 8% C02, 13% O2; 5% CO2, 16% O2; or air (0.03% CO2, 21% O2). Berries were evaluated after 7, 11 and 16 days. Berries stored in the highest CO2 atmosphere (15% C02, 6% O2) maintained higher firmness, glossiness, lighter color (higher hue angle), and had less weight loss and decay. Air-stored berries tasted sweeter and juicer to the panelists than berries from other treatments.

Introduction

Raspberry is a high value fruit with high perishability and short shelf life. Decay, leakiness, loss of firmness and off-flavors are the most common limiting factors contributing to short storage life. High CO2 atmospheres have been reported to control raspberry decay during storage (Aagar and Sterif, 1996). CA with reduced O2 and/or elevated C02 can retard senescence of fruits by slowing softening, respiration and ethylene production rates, and controlling pathogen growth. The objective of this research was to study the effect of different atmospheres on raspberry postharvest storage quality.

Methods

Raspberries were obtained immediately after harvest and
cooling and transported to UC Davis. Raspberries were stored at
5°C in each of the atmosphere treatments. The atmospheres
were humidified prior to fruit exposure in a flow-through
system with 3 replications per atmosphere.

T1 -15% C02, 6% O2
T2 – 8% C02, 13% O2
T3 – 5% CO2, 16% O2
T4 – 0.03% CO2, 21% O2 (Air)

One clamshell of raspberries per treatment and replication was
evaluated after 7, 11 and 16 days. Firmness, leakiness,
discoloration, glossiness, decay incidence and decay severity
were evaluated by hand feel, visual inspection or a combination
of both using hedonic scales. Raspberry color was measured
with a Minolta Colorimeter and hue° was calculated.
The sensory quality of the treated raspberries was also
evaluated for texture, flavor and aroma.

Results

Raspberries stored in 15% C02, 6% O2 showed better performance over raspberries stored in other atmospheres, with significant differences in firmness, leakiness and weight loss.

During the 16 day experiment, hue° decreased (the raspberries became darker red); however, raspberries stored in 15% C02, 6% O2 maintained significantly higher hue° (lighter red color) and higher glossiness compared to the other treatments across all the evaluation dates

Decay percentage was lower in raspberries stored in 15% CO2, 6% O2 treatment and higher in air stored raspberries.

In sensory evaluations, 15% C02, 6% O2 treatment significantly
stood out in firmness (month feel) among the other treatments.
However, raspberries stored in air were perceived by panelists as
sweeter and juicer compared to the other treatments.
Raspberries stored in 8% C02, 13% O2 maintained the highest
raspberry flavor after 16 days. Air stored raspberries were not
included in the sensory panel after 16 days storage due to mold.

Summary

• Storing raspberries in 15% CO2 maintained higher firmness and lighter red color, and resulted in less leakiness, decay and weight loss.
• Raspberries stored in all atmospheres lost weight and firmness and increased in leakiness over time.
• Titratable acidity remained higher in raspberries stored in 15% CO2.
• Soluble solids content decreased over time, regardless of the treatment.
• Air-stored berries tasted sweeter and juicer to the panelists than berries from other treatments.

This article appeared on the North American Raspberry & Blackberry Association at https://www.raspberryblackberry.com/posters-at-the-2021-conference/raspberry-post-harvest-qualities-as-affected-by-controlled-atmosphere-storage/