Investigación Sobre Los Cambios En La Composición Bacterial De Flores De Zuchchini Expuestas A Temperaturas De Refrigeración

The Scientific World Journal Volume 2012, Article ID 127805, 6 pages doi:10.1100/2012/127805

The cientificWorldJOURNAL

Research Article Changes in Bacterial Composition of Zucchini Flowers Exposed to Refrigeration Temperatures
F. Baruzzi, M. Cefola, A. Carito, S. Vanadia, and N. Calabrese
Institute of Sciences of Food Production, National Research Council of Italy (CNR-ISPA), Via. G.Amendola 122/o, 70126 Bari, Italy Correspondence should be addressed to F. Baruzzi, federico.baruzzi@ispa.cnr.it Received 20 October 2011; Accepted 8 December 2011 Academic Editor: Mario Vaneechoutte Copyright © 2012 F. Baruzzi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium,provided the original work is properly cited. Microbial spoilage is one of the main factors affecting the quality of fresh fruits and vegetables, leading to off-flavor, fermented aroma, and tissue decay. The knowledge of microbial growth kinetics is essential for estimating a correct risk assessment associated with consuming raw vegetables and better managing the development of spoilage microorganisms.This study shows, for the first time, that only a part of total microbial community, originally present on fresh harvested female zucchini flowers, was able to adapt itself to refrigerated conditions. Through the study of microbial growth kinetics it was possibleto isolate forty-four strains belonging to twenty-two species of the genera Acinetobacter, Arthrobacter, Bacillus, Enterobacter, Erwinia,Klebsiella, Pantoea, Pseudoclavibacter, Pseudomonas, Serratia, Staphylococcus, and Weissella, suggesting Enterobacteriaceae as potentially responsible for pistil spoilage.

1. Introduction
The fresh-like and healthy traits of ready-to-use (RTU) products such as leafy vegetables (lettuce, rocket, spinach, etc.) and fruits (melon, pineapple, apricot, peach, apple, etc.), with a minimal time ofpreparation before consumption, are characteristics sought by consumers [1–3]. Microflora causing release of off-flavors and tissue decay is well known in both RTU vegetables and fruits [4–9]. The dominating bacterial population during low temperature storage mainly consists of species belonging to the Pseudomonadaceae and Enterobacteriaceae; besides some species belonging to the lactic acid bacteriaand moulds may be present at relatively lower numbers [4, 10–13]. The consumption of zucchini (Cucurbita pepo L.) flowers with the immature fruit attached is spread in many countries, specially in the Mediterranean area, but, due to their high perishability, they are in general marketed only locally. Different authors [14, 15] studied the effects of cold storage on zucchini flowers processed as a newRTU vegetable; these papers showed that the shelf life of flowers was affected either by low storage temperatures and by cultivars. However, no study is reported in literature on the evolution under refrigerated conditions of natural microbial

population occurring on female zucchini flowers that, composed by petals and pistil, presents different tissues and nutrient availabilities. Aim of this workwas to gain a better knowledge about the survival of natural microorganisms occurring on female zucchini flowers, potentially involved in vegetable spoilage, in order to lay the basis for the development of a new RTU vegetable.

2. Materials and Methods
2.1. Microbiological Analyses of Zucchini Flowers. Microbial evaluation on growth kinetics in zucchini female flowers (cv. Aquilone) was carriedout in two consecutive years (trial A and B). Clean flowers, with their immature fruit attached, were harvested and immediately subjected to microbiological analyses. At the same time, zucchini flowers were stored, as harvested, in gas permeable polypropylene open bags at 4◦ C ± 1◦ C for 11 days. Three replicate bags of eight zucchini flowers were prepared for each sampling time (4, 8, and 11...