Combined pre-treatments effects on zucchini (Cucurbita pepo L.) squash microbial load reduction

Neves, Filipa. I. G.; Silva, Cristina L. M.; Vieira, Margarida

Publication

Combined pre-treatments effects on zucchini (Cucurbita pepo L.) squash microbial load reduction

2019Journal article

dc.contributor.author	Neves, Filipa. I. G.
dc.contributor.author	Silva, Cristina L. M.
dc.contributor.author	Vieira, Margarida
dc.date.accessioned	2020-01-08T10:53:55Z
dc.date.available	2020-01-08T10:53:55Z
dc.date.issued	2019
dc.description.abstract	Freezing vegetables requires pre-treatments to reduce microbial load and destroy enzymes that impair the frozen product quality. So far blanching has been the most effective pre-treatment, preferred by the food industry, despite its severity: heating up to temperatures close to 100 °C for 1-3 min causes sensory and texture changes in most horticultural products. Alternative blanching treatments, using UV-C radiation combined with milder thermal treatments or with thermosonication, may improve the quality of the final frozen vegetables. Zucchini (Cucurbita pepo L.), the vegetable under study, has an availability in fresh restricted to a season, needing therefore to be often frozen to be used throughout the year. In this study, its surface was first inoculated with two vegetable contaminants, Enterococcus faecalis and Deinococcus radiodurans cells, which are resistant, respectively, to high temperatures and to radiation and then submitted to several blanching treatments, single or combined, and the effect on these microorganisms reduction was evaluated. As single treatments, water blanching (the control treatment, as it is the blanching treatment traditionally used) was applied up to 180 s at temperatures ranging from 65 to 90 °C, and UV-irradiation applied in continuous. As combined pre-treatments, water blanching combined with UV-C (continuous or in pulses), and thermosonication (20 kHz at 50% of power) combined with UV-C pulses were also studied. The continuous UV-C radiation incident irradiance was 11 W/m2 up to 180 s, and the pulses at incident radiance of 67 W/m2, lasting 3.5 s each (35 pulses). Mathematical modeling of bacterial reduction data was carried out using the Bigelow, the Weibull and Weibull modified models, and estimation of their respective kinetic parameters proved that the latter models presented a better fit below 75 °C. The best results proved to be the combination of water blanching at temperatures as low as 85 °C during <2 min with 25 pulses of UV-C (incident irradiance of 67 W/m2) or thermosonication at 90 °C also combined with UV-C pulses, both resulting in 3 log reductions of both microorganisms under study. These results proved to overcome what industry is requiring so far (a 2 log microbial reduction in 3 min), hence minimizing quality changes of frozen zucchini.	pt_PT
dc.description.sponsorship	SFRH/BD/19883/2004
dc.description.version	info:eu-repo/semantics/publishedVersion	pt_PT
dc.identifier.doi	10.1016/j.ijfoodmicro.2019.108257	pt_PT
dc.identifier.uri	http://hdl.handle.net/10400.1/13409
dc.language.iso	eng	pt_PT
dc.peerreviewed	yes	pt_PT
dc.publisher	Elsevier	pt_PT
dc.rights.uri	http://creativecommons.org/licenses/by/4.0/	pt_PT
dc.subject	Bacterial load	pt_PT
dc.subject	Cucurbita	pt_PT
dc.subject	Deinococcus	pt_PT
dc.subject	Enterococcus faecalis	pt_PT
dc.subject	Food preservation	pt_PT
dc.subject	Freezing	pt_PT
dc.subject	Temperature	pt_PT
dc.subject	Vegetables	pt_PT
dc.subject	Water	pt_PT
dc.title	Combined pre-treatments effects on zucchini (Cucurbita pepo L.) squash microbial load reduction	pt_PT
dc.type	journal article
dspace.entity.type	Publication
oaire.citation.startPage	108257	pt_PT
oaire.citation.title	International Journal of Food Microbiology	pt_PT
oaire.citation.volume	305	pt_PT
person.familyName	Vieira
person.givenName	Margarida
person.identifier.ciencia-id	3314-4EFC-1E4A
person.identifier.orcid	0000-0003-2774-706X
person.identifier.rid	E-1805-2012
person.identifier.scopus-author-id	7202140775
rcaap.rights	restrictedAccess	pt_PT
rcaap.type	article	pt_PT
relation.isAuthorOfPublication	338c2b9c-fbe6-4fc1-af2d-8152a6560119
relation.isAuthorOfPublication.latestForDiscovery	338c2b9c-fbe6-4fc1-af2d-8152a6560119