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X-ray microtomography provides new insights into vacuum impregnation of spinach leaves

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Bibliographic Details
Summary:Vacuum impregnation is used in the food industry to facilitate the impregnation of porous products with, e.g. firming, antioxidant, antimicrobial or cryoprotective agents. X-ray micro-tomography (CT) was used to study the process of vacuum impregnation in spinach leaves. Low (300 mbar absolute pressure) and mild vacuum (150 mbar absolute pressure) impregnation protocols were used to impregnate an isotonic solution of trehalose in the leaves and CT was used to make observations of the cross section of the impregnated samples and quantify their porosity. Results revealed that the free volume in the spongy mesophyll is easier to impregnate than the spaces around the palisade mesophyll. The low vacuum impregnation protocol provoked less impregnation close to the edge of the leaf than in its centre, probably accounting for an influence of the tissue structure on impregnation. The vacuum impregnation protocols tested in this investigation drastically decreased the proportion of large pores (>100 m) and increased the proportion of small pores (<50 m). The mild vacuum impregnation protocol, which was designed on the basis of measured apparent porosity, did not achieve full impregnation of the tissue.
Main Authors:Panarese, Valentina
Other Authors:Herremans, Els; Cantre, Dennis; Demir, Eda; Vicente, A. A.; Galindo, Federico Gómez; Nicolai, Bart; Verboven, Pieter
Subject:Microstructure Porosity Spinacia oleracea
Year:2016
Country:Portugal
Document type:article
Access type:open access
Associated institution:Universidade do Minho
Language:English
Origin:RepositóriUM - Universidade do Minho
Description
Summary:Vacuum impregnation is used in the food industry to facilitate the impregnation of porous products with, e.g. firming, antioxidant, antimicrobial or cryoprotective agents. X-ray micro-tomography (CT) was used to study the process of vacuum impregnation in spinach leaves. Low (300 mbar absolute pressure) and mild vacuum (150 mbar absolute pressure) impregnation protocols were used to impregnate an isotonic solution of trehalose in the leaves and CT was used to make observations of the cross section of the impregnated samples and quantify their porosity. Results revealed that the free volume in the spongy mesophyll is easier to impregnate than the spaces around the palisade mesophyll. The low vacuum impregnation protocol provoked less impregnation close to the edge of the leaf than in its centre, probably accounting for an influence of the tissue structure on impregnation. The vacuum impregnation protocols tested in this investigation drastically decreased the proportion of large pores (>100 m) and increased the proportion of small pores (<50 m). The mild vacuum impregnation protocol, which was designed on the basis of measured apparent porosity, did not achieve full impregnation of the tissue.

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