The effects of storage conditions and ascorbic acid treatment on shelf life of cauliflower, broccoli, and rutabaga

Abstract

In Iceland, vegetables are difficult to cultivate outdoors due to the cool climate. Yet, cauliflower, broccoli and rutabaga yield may exceed market demand. Several studies abroad confirm that the sensory quality of vegetables has a significant impact on consumer acceptability and purchase behaviour. Therefore, it is necessary to find ways to prolong the shelf life of these vegetables and preserve their quality and reduce waste. This study aimed to obtain new knowledge about the sensory properties (appearance, odour, flavour, texture, and overall quality) and quality of cauliflower, broccoli, and rutabaga under two different conditions (i.e., packed with Clarus polyolefin shrink film and unpacked) during storage at regulated storage conditions of 0°C-2°C temperature and 90%-95% humidity, Additionally the aim was to design sensory schemes to measure the sensory quality of vegetables. Lastly, the aim was to investigate the effect of ascorbic acid (i.e., vitamin C) as a preservative to extend the shelf life of fresh-cut cauliflower and broccoli at regulated storage of 0°C-2°C temperature and 90%-95% humidity. The study was divided into experiment 1 (packed and unpacked vegetables) and experiment 2 (effect of ascorbic acid). The experiments were conducted in September to December 2021. A sensory scheme was designed for each vegetable (i.e., cauliflower, broccoli, and rutabaga). Samples for both experiments were obtained from local farms. Parameters measured in both experiments were sensory evaluation by eight trained sensory panellists, microbial count, water content, vitamin C content, weight loss, and colour change using CIL lab L, and b. Temperature and humidity were monitored and recorded throughout the studies. In experiment 1, sensory properties of all three vegetables (cauliflower, broccoli, and rutabaga) were better in packed samples than unpacked samples. Packed samples also retained more water and lost less weight. Microbial count was lower in unpacked samples than in packed samples (> 106). Vitamin C decreased in all vegetables in both conditions. Colour changed in both conditions. Temperature and humidity were stable, however different positions in the storage room recorded different temperature and humidity. In experiment 2, treatment with ascorbic acid had no effect as preservative and extending shelf life. Cauliflower and broccoli had rather similar results for sensory properties evaluation and other parameters, total bacteria count was within limits, but yeast and mould were found in both control and treated samples. Yeasts and moulds are the predominant microflora associated with fresh vegetables. Water content decreased more in broccoli than cauliflower but was rather stable in cauliflower. Weight loss was seen in both control and treated samples. Due to the treatment with ascorbic acid, the treated samples contained more vitamin C than the control samples; nevertheless, a reduction was observed after the second measurement and continued until the end of the experiment. As a result of the treatment, the colour of the samples changed; this was most noticeable in the vegetables stalks, where the cut surface was exposed to the treatment. Humidity and temperature were rather stable in the storage room during the experiment.