Effects of packaging on shelf life of fresh celery

doi:10.1016/j.jfoodeng.2008.06.011

Journal of Food Engineering

Volume 90, Issue 1, January 2009, Pages 124-128

https://doi.org/10.1016/j.jfoodeng.2008.06.011 Get rights and content

Abstract

Celery could be sold in a wide range of presentations, from without any kind of packaging until ‘ready to eat’. The aim of this research was to analyse the effect of two packaging films on quality loss of celery due to frequent changes in temperature and relative humidity as well as to varying respiration rates. Shelf life could be extended by limiting storage temperature variations. Weight loss, discoloration and texture changes appear to be the primary symptoms for deterioration in quality. Celery stalks were packed in polyolefin (co-extruded polyethylene and polypropylene) with an antifogging additive (AF) and micro perforated polypropylene (MP). Samples were kept at 4 ± 1 °C, 90% RH for 35 days, using unpacked celery as control. Weight loss, firmness, pH, soluble solid content, titratable acidity, petioles and leaves colour, and total phenols were determined. The results showed that colour intensity and firmness decreased during storage; weight loss in AF packed celery was lower than 3%. Tiny accumulations of condensate in AF didn’t reduce shelf life, so it may be considered the most suitable packaging material for extending shelf life of celery stalks.

Introduction

Celery is a hypo-calorific vegetable: every edible 100 g gives only 20 kcal, yet nutritionally it has good vitamin C (32.00 mg), and vitamin A (0.207 mg) levels, and is rich in potassium (280.00 mg).

Fresh-cut celery is part of an array of ready to eat produce available in food markets, thanks to technologically advanced packaging techniques which limits moisture loss and gas exchange and which help to maintain product freshness and quality during storage (Robbs et al., 1996).

The storage of minimally processed celery has been widely studied (Robbs et al., 1996, Loaiza-Velarde et al., 2003, Viňa and Chaves, 2003, Viňa and Chaves, 2006, Gomez and Artes, 2005), but it is not very widespread in Italy. For this reason, packing whole celery in different plastic films provides convenience for Italian consumers and benefits for producers. Consumers identify safety and guarantee with packaged vegetables, while producers deliver longer shelf life and better hygiene during merchandising.

Vegetable deterioration occurs progressively during storage and its cumulative effect renders the food undesirable to consumers. Frequently the microbial proliferation that accompanies the food spoilage of unprocessed or minimally processed food is considered the first limit to shelf life, but physical freshness parameters are immediately recognised by consumers.

The first signs of quality decay and decreasing shelf life for celery are the loss of green colour and the onset of pithiness (Gomez and Artes, 2005). Furthermore, during handling, cutting, washing and rinsing for minimal processing, mechanical damage occurs, together with oxidative stress (Viňa and Chaves, 2006). Vascular browning at the ends of fresh-cut celery petioles is one of three major changes that reduce its quality (Saltveit and Mangrich, 1996). According to Viňa and Chaves (2003), the main factors reducing celery quality are physiological effects, the increased rate of several biochemical reactions and damage induced by microorganisms. These authors recommend for whole celery plants storage temperatures of −0.6 to 0 °C, together with 92–95% of relative humidity to obtain a shelf life of about 8 weeks.

During transport and commercial distribution it is difficult to maintain these recommended conditions so celery is subject to variables like changing temperature and humidity, but also to mechanical damage and remarkable weight loss, sometimes higher than 30%, in which case it cannot be marketed (Tei et al., 2000).

The aim of this work was to study the influence of two polymeric films: polyolefin anti-fog and micro perforated on shelf life of whole celery.

Section snippets

Plant materials

Celery plants (Apium graveolens L.) var. Dulce cv. D’Elne were collected in a local farm in autumn at marketable ripeness. Samples were uniformly treated with nutritive solutions containing 100 kg/ha mineral nitrogen (NH₄)₂SO₄, then harvested following agronomic sampling procedure. Celery stalks were brought to the laboratory, carefully inspected, and the leaves and basal disc were bruised to remove any soil residues. Each sample was weighed, packaged and marked to estimate weight loss during

Weight loss

Weight loss is a physiological event in fresh vegetables that can be limited by controlling storage temperature and humidity, but also by using appropriate packaging. In this work, weight loss increased with storage time for both plastic films. In MP film, as expected, weight loss was high and ranged from 10% at the first sampling to 33.6% at the end of storage (31 days), similar to controls. Weight loss in AF packed celery was lower than 3%, varying negligibly during storage (Fig. 1); the

Conclusions

Package in the AF and MP films allows a shelf life of 31 days while, as expected, unpacked control was unacceptable after 20 days. Celery’s qualitative parameters as weight loss, texture and colour variations observed in AF had values closer to fresh samples.

The reduced total weight loss of celery in AF film, lower than 3% and varying negligibly during storage minimized package condensation and extended shelf life to beyond 31 days.

Texture decreased during storage, and the AF samples conserved

Acknowledgement

Authors really appreciated the contribution of Filippo Tomaselli for his helps in the statistical analysis.

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Effects of packaging on shelf life of fresh celery

Abstract

Introduction

Section snippets

Plant materials

Weight loss

Conclusions

Acknowledgement

Lebensmittel – Wissenschaft und Technologie

Postharvest and Technology

Food Chemistry

Official Methods of Analysis of the Association of Official Analytical Chemist