Masters Theses

Date of Award

12-2020

Degree Type

Thesis

Degree Name

Master of Science

Major

Plant Sciences

Major Professor

Carl Sams

Committee Members

Carl E. Sams, Dennis E. Deyton, Curtis R. Luckett

Abstract

Broccoli (Brassica oleracea L. var. italica) is a cool-weather vegetable that is grown for its edible flowering heads and stalks. Broccoli inflorescences are immature plant organs with high respiration rates, resulting in a rapid loss of quality after harvest. The effects of cooling and storage methods on postharvest broccoli quality were evaluated based on metabolite contents of broccoli samples stored for 0, 7, 14, 21, 28, and 35 days. Sugar and organic acid contents were measured for broccoli harvested Fall 2018. Contents were compared for two cultivars (‘Diplomat’ and ‘Arcadia’) and two temperature treatments (not precooled and stored at 6 [superscript zero] ⁰C, and precooled with an ice slurry and stored at 0 ⁰C in ice). Glucosinolate, volatile, carotenoid, and chlorophyll contents were measured for broccoli harvested Summer 2019. Contents were compared for two cultivars (‘BH053’ and ‘Emerald Crown’) and two temperature treatments (precooled with top icing and stored at 7 ⁰C, and precooled with an ice slurry and stored at 0 ⁰C in ice). Cultivar, storage temperature, and storage time significantly affected metabolite contents in broccoli. Sucrose content was significantly greater for ‘Diplomat,’ while organic acid content was greater for ‘Arcadia.’ Carotenoid, and chlorophyll contents were significantly greater for ‘BH053,’ while glucosinolate and dimethyl disulfide content was significantly greater for ‘Emerald Crown.’ Broccoli stored at 7 ⁰C had significantly greater dimethyl disulfide contents while broccoli stored at 0 ⁰C had significantly greater sucrose and glucosinolate contents. Sugars, organic acids, carotenoids, and chlorophyll significantly decreased within 21 days during storage, while glucosinolates were unaffected by storage time. However, the sulfur-containing volatiles increased from 21 to 35 days. These results indicate that the postharvest quality of broccoli was significantly greater for ‘Diplomat’ than for ‘Arcadia,’ and greater for ‘BH053’ than for ‘Emerald Crown.’ In addition, these results suggest that storage iii at lower temperatures helps to maintain postharvest quality of broccoli by decreasing the loss of nutritionally important glucosinolates and sugars, while preventing the production of volatiles responsible for off-odors.

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