The effect of high pressure processing on nutritional value and quality attributes of Cucumis melo L.

https://doi.org/10.1016/j.ifset.2007.08.001Get rights and content

Abstract

To determine the effect of cultivar on high pressure processing (HPP) performance three commercial melon varieties were assessed before and after HPP for vitamin C and β-carotene by HPLC and for ferric ion reducing capacity (FIRC) using the Ferric Reducing Ability of Plasma (FRAP) assay. Total titrable acids (TTA), °Brix and colour were also recorded for fresh,−HPP (material cut and packaged) and +HPP samples (material cut, packaged and subject to HPP). The HP process was non-thermal so as to determine the effect of pressure alone on these phytochemicals. There were significant differences between cultivars in vitamin C, β-carotene, TTA, °Brix and colour parameters in fresh samples prior to HPP. HPP did not have an effect on TTA or °Brix, but colour was adversely affected. FIRC and vitamin C concentrations were decreased by HPP and these losses were cultivar dependent for vitamin C. Levels of β-carotene were significantly increased. Cultivar was identified as an important parameter in raw material selection for HPP and retention of vitamin C as a good measure of both quality and cultivar suitability.

Industrial relevance

There is an increasing consumer demand for fresh, natural and healthy fruit and vegetable products with an extended shelf life. This demand is driving industry to look at alternative preservation technologies. HPP has the potential to deliver safe, preserved fruit and vegetables through enzyme inactivation of microbe destruction. HPP removes the need for additives or preservatives and the process is therefore viewed as closer to “natural” by consumers. We show that HPP results in minimal loss of sensorial properties and health-promoting phytochemicals; thus providing consumers a high quality, healthy product with extended shelf life. The introduction of non-thermal processing techniques has the potential to move the focus of the Australian food processing industry from safety to the dual aims of safety and health, resulting in an increase of health-promoting phytochemicals in highly consumed processed foods.

Introduction

High pressure processing (HPP) is an emerging food preservation technique based on the application of very high hydrostatic pressures (up to 700 MPa) to food, reportedly resulting in the inactivation of food-borne microorganisms and enzymes involved in food spoilage (Bayındırlı, Alpas, Bozoğlu & Hızal, 2006). Organoleptic properties are thought to be unaffected by HPP and nutritional attributes only minimally affected (Ahmed and Ramaswamy, 2006, Sancho et al., 1999). Therefore, HPP may be a suitable platform technology to meet the growing demand for high quality, nutritional, safe foods.

A diet rich in fresh fruit and vegetables has been epidemiologically linked to the reduction of many types of human cancers (Block et al., 1992, Steinmetz and Potter, 1991). The validation of health claims will help establish preservation technologies with minimal impacts on the bioactive compounds that are the basis of that epidemiological link. Conventional thermal preservation processes are known to adversely affect the organoleptic and nutritional properties of food. At the present time there is encouraging, but limited data available on the effects of HPP on these compounds in comparison to fresh and thermally processed products (Polydera, Stoforos & Taoukis, 2005).

The effect of HPP is variable, and dependent on not only HPP operating conditions but food composition as well (Hendrickx et al., 1998, Matser et al., 2004). The effect of HPP can vary depending on processing conditions (pressure, hold time, pH and temperature) and form (whole, puree and juice). The food matrix can be altered by these variables consequently impacting on the effectiveness of HPP. The type of plant material (i.e. species) is also important but rather less is known about the impact of cultivar within species on food quality following HPP. Specific investigations are needed to determine the parameters required to optimise the quality and nutrition of individual HPP food products.

This study investigated the impact of HPP on three commercial melon cultivars. Melon was selected as it is a soft-fleshed fruit with depth of tissue and is known to be a good source of β-carotene and vitamin C. Vitamin C, β-carotene, ferric ion reducing capacity (FIRC), total titratable acids (TTA), refractible soluble solids (°Brix) and colour were measured in freshly harvested fruit (fresh), fruit cut and packaged for HPP (−HPP), and fruit cut, packaged and subject to HPP (+HPP).

Section snippets

Melon samples

Three cultivars of melon (Cucumis melo L.)—two netted melons (Northern Sky and Southern Cross) and one charantais type (Chantele) (Syngenta, Aust.)—were grown under black plastic covers with drip irrigation. There were four replicate plots per cultivar and each plot was 3.5 m in length with plants 50 mm apart within the rows. Pre-sowing fertilizer consisted of N, P and K (12:5:15) (Hydrocomplex, Yarra, Aust. Pty. Ltd.) at a rate of 60 g per m2. Melons were harvested as per commercial practices.

The effect of cultivar and HPP on organoleptic quality

°Brix and TTA are important factors in determining eating quality of fruits and vegetables. °Brix in −HPP and +HPP samples was unaltered compared to fresh. There were significant cultivar differences in °Brix (P < 0.001) (Table 1), but neither packaging for HPP nor the HPP process itself had any impact on °Brix levels. The lack of any impact of HPP on °Brix and TTA was consistent across cultivars. Cultivar effects were not apparent for TTA, however TTA was significantly higher in −HPP samples

Acknowledgements

We thank Dr. Nick Smale and Ms Emma Winley from Food Science Australia for conducting the HPP; and, Dr. Tony Bird and Ms. Jenny McInerney from the CSIRO Human Nutrition for assistance with the methodology. We would also like to thank Syngenta (Aust.) for the provision of seed of the melon cultivars used in this study.

Cited by (71)

  • HPP for improving preservation of vitamin and antioxidant contents in vegetable matrices

    2020, Present and Future of High Pressure Processing: A Tool for Developing Innovative, Sustainable, Safe and Healthy Foods
View all citing articles on Scopus
View full text