Effects of pretreatments on quality attributes of long-term deep frozen storage of vegetables: a review

Abstract

As one of the essential parts in human diet, vegetables are important in health keeping and their consumption increases continuously. Due to their highly perishable nature, the shelf life of fresh vegetables is considerably short, due to cellular respiration, microorganism, enzyme reaction, oxidation and so on. Therefore, short- and long-term storages of vegetables are required and various methods and technologies are applied for different commercial goals. For long-term storage, deep frozen storage is one of the most widespread used preservation methods for vegetables, as under temperatures low enough, the rate of most deteriorative reactions and microbial activities are significantly reduced. This review provides a critical comprehensive summary of long-term storage (≥6 months) vegetables under low temperatures (≤ −18 °C), and effects of the storage methods on various quality attributes of vegetables, such as texture, colour, contents of ascorbic acid, chlorophyll and carotenoids. Besides, the impacts of common pretreatments prior to freezing on the subsequent frozen storage are also briefly discussed. The current review shows that although some important biochemical attributes are more or less deteriorated and the quality loss of them is inevitable, a substantial portion of quality attributes appear to be stable during long-term deep frozen storage especially the physical parameters. Meanwhile, pretreatments prior to freezing, such as blanching process, also show significant influence on quality preservation in subsequent storage. Therefore long-term deep frozen storage can be applied as an effective storage method under proper conditions of pretreatments and storage.

Keywords:

• vegetable
• long-term storage
• deep freezing
• pretreatments
• preservation

Acknowledgments

The authors are grateful to the National Key R&D Program of China (2017YFD0400404) for its support.

Disclosure Statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors are grateful to the National Key R&D Program of China (2017YFD0400404) for its support. This research was also supported by the Collaborative Innovation Major Special Projects of Guangzhou City (201604020057), the Agricultural Development and Rural Work of Guangdong Province (2017LM4173), the International and Hong Kong – Macau - Taiwan Collaborative Innovation Platform of Guangdong Province on Intelligent Food Quality Control and Process Technology & Equipment (2015KGJHZ001), the Guangdong Provincial R & D Centre for the Modern Agricultural Industry on Non-destructive Detection and Intensive Processing of Agricultural Products, the Common Technical Innovation Team of Guangdong Province on Preservation and Logistics of Agricultural Products (2016LM2154) and the Innovation Centre of Guangdong Province for Modern Agricultural Science and Technology on Intelligent Sensing and Precision Control of Agricultural Product Qualities.