Freeze‐thaw Damage to Protoplasmic Structure in High Moisture, Edible Plant Tissues

Mohr, W.

doi:10.1111/j.1745-4603.1971.tb01008.x

Cited by 7 publications

(7 citation statements)

References 24 publications

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“…Freeze-thaw induced alterations to the fine structure of tomato fruit, rhubarb stalk, Mung bean sprout, and fig fruit parenchyma have been reported in earlier studies (Mohr and Stein, 1969;Mohr, 1971). Representative of many edible fruit tissues, these have a high moisture and low starch content.…”

Section: Introductionmentioning

confidence: 52%

“…comb, 1969), and some intact lengths of the plasmalemma. Although these cells are highly vacuolated, the cytoplasmic layer contains a much 'richer' supply of structural components than the fruit cells studied earlier (Mohr, 1971) which were even more highly vacuolated. This could be a factor contributing to the 'not excessive' disruption of cytoplasmic structure observed in frozen-thawed spinach.…”

Section: A Spinach Leafmentioning

confidence: 65%

“…Immediately after completion of the intended freezing and thawing treatment, representative portions of the tissue were fixed in 2% glutaraldehyde buffered with 0.02 M sodium phosphate and prepared for electron microscopy (Mohr and Cocking, 1968). The method included glutaraldehyde-osmium fixation, staining of the tissue pieces with uranyl acetate during alcohol dehydration, embedding in styrene-methacrylate, and post-staining the sections with lead citrate.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…Since cellular starch frequently has been linked with textural properties of edible plant tissues (e.g. Reeve, 1970;Mohr, 1972), vegetable tissues varying in starch content as well as in textural response to freeze-thawing were chosen for the present study. Spinach is a typical low starch/high moisture leafy vegetable whose texture is greatly changed by freeze-thawing.…”

Section: Introductionmentioning

confidence: 99%

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Freeze‐thaw (And Blanch) Damage to Vegetable Ultrastructure

Mohr

1974

Journal of Texture Studies

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The parenchyma cells of three vegetable tissues varying in starch content as well as in textural response to freeze‐thawing were studied ultrastructurally before and after controlled freeze‐thaw regimes. Similar tissue samples were also studied after blanching and after the blanch‐freeze‐thaw combination. Subcellular structures were altered more drastically by blanching than by freeze‐thawing. There was much less fine structural disruption in the high starch tissue (green pea cotyledon) than in the tissues of lower starch content (spinach leaf and green bean pod) following all processing treatments. As judged by sensory evaluation, peas also underwent less textural change on processing than the other tissues studied. The minimal ultrastructural change observed in peas may be associated with certain cell characteristics: high starch content, abundant protoplasmic structure, and resultant low degree of vacuolation. It is concluded that ‐ of these ‐ the starch granule component is the major contributor to texture. This probably applies in the case of most processed vegetable tissues of relatively high starch content. The protective role of cellular starch is discussed in relation to fine structure retention and to texture.

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Section: Introductionmentioning

confidence: 52%

Section: A Spinach Leafmentioning

confidence: 65%

Section: Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Freeze‐thaw (And Blanch) Damage to Vegetable Ultrastructure

Mohr

1974

Journal of Texture Studies

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“…In contrast, our goal is to develop fruit and vegetable products with improved postharvest freeze/thaw quality based on the property of antifreeze protein to inhibit ice recrystallization. Changes in the quality of produce as a result of freezing and thawing can occur in several ways [20,32]: there will be membrane damage, with consequent loss of the liquid-retaining properties of cells, and therefore succulent plant tissues lack turgor upon thawing [26]. In addition, the dehydration of cellulose during freezing may account for changes in textural qualities of thawed fruits and vegetables [31].…”

Section: Discussionmentioning

confidence: 99%

Expression of antifreeze proteins in transgenic plants

et al. 1991

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The quality of frozen fruits and vegetables can be compromised by the damaging effects of ice crystal growth within the frozen tissue. Antifreeze proteins in the blood of some polar fishes have been shown to inhibit ice recrystallization at low concentrations. In order to determine whether expression of genes of this type confers improved freezing properties to plant tissue, we have produced transgenic tobacco and tomato plants which express genes encoding antifreeze proteins. The afa3 antifreeze gene was expressed at high steady-state mRNA levels in leaves from transformed plants, but we did not detect inhibition of ice recrystallization in tissue extracts. However, both mRNA and fusion proteins were detectable in transgenic tomato tissue containing a chimeric gene encoding a fusion protein truncated staphylococcal protein A and antifreeze protein. Furthermore, ice recrystallization inhibition was detected in this transgenic tissue.

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