Life Sciences Commons^™

Scanning Electron Microscopy Structure And Firmness Of Papain Treated Apple Slices, Yaguang Luo, Max E. Patterson, Barry G. Swanson

Food Structure

'Mcintosh' apple (Malus domesrica Borkh.) slices were treated with papain. Textural changes were recorded with an Instron Universal Testing Machine. Structural changes and distribution of microorganisms in apple tissues after treatment were observed with a scanning electron microscope (SEM). Apple slices submerg ed in a 1% papain solution were significantly firmer than apple slices submerged in the distilled water control for a 24 hour period (P < 0.05). Three and four days after slicing , a significantly smaller decay index was observed on the apple slices submerged in papain solution than on the control slices. Under SEM, less severe cell wall breakdown was observed on the apple tissues treated with papain than on apple tissues without treatment. Less spores were also observed on the papain treated apple slices than apple slices without treatment. Apple tissues treated with papain solution and distilled water also demonstrated noticeable st ru ctural differences. The apple tissues treated with papain solution for 18 hours retained the original cell structure while the cells in the apple tissues treated with distilled water collapsed.

The Role Of Cell Wall Structure In The Hard-To-Cook Phenomenon In Beans (Phaseolus Vulgaris L.), Ilan Shomer, Nachman Paster, Pinhas Lindner, Rosa Vasiliver

Food Structure

Differences in structure, water uptake and efflux of solubles were found between normal and hard-to-cook beans (Phaseolus vulgaris L.) The staining characteristics of hard beans were different from those of the normal in both non-cooked and cooked tissue, especially in the cell walls. The three zones of the cell wall - the middle lamella, the primary and the secondary walls - were found in both normal and hard-to-cook beans. The primary cell wall of both normal and hard beans was partially degraded upon cooking, as seen by bright fields within the fibrillar pattern. The ultrastructure of the non-cooked secondary cell …

The Effect Of Irradiation On Starch Content In Golden Delicious Apples, E. Kovacs, A. Keresztes

Food Structure

Starch content in apple (Golden Delicious) skin and flesh was studied as a function of radiation dose (0, 0.5, 1, 2 and a 5kGy) after 8 weeks shelf life (16 C, 80-90% RH).

Starch was generally not found in the flesh with the exception of the 5 kGy sample. Starch grains were observed, however, in plastids of the epidermis and especially in the hypodermis in correlation with the radiation dose. 1 kGy dose caused a significant effect (p>99, 98%) on retardation of starch breakdown measured by electron microscopic morphometry and chemical analysis.

Analysis showed that increasing radiation dose increased …

The Effects Of Gamma Irradiation And Calcium Treatment On The Ultrastructure Of Apples And Pears, E. Kovacs, A. Keresztes, J. Kovacs

Food Structure

The post-storage quality of fruits depends on the ultrastructure of the outer tissues and on the fruit mineral composition (mostly on calcium). Pectins and their bonds with calcium play a central role in the tissues during ripening.

During senescence the middle lamella disappears from the cell walls, the fruits become soft and cell wall reticulation can be seen. There are changes within the cells too; plasmalemma separates from the wall, tonoplast from the cytoplasm, and plastids, mitochondria and nuclei are disorganized.

The ultrastructure of the skin and flesh of apples and pears were studied as a function of treatments (calcium, …

Structural Binding Properties Of Silvercarp (Hypophtalmichthys Molitrix) Muscle Affected By Nacl And Cacl2 Treatments, Ilan Shomer, Zwi G. Weinberg, Roza Vasiliver

Food Structure

The texture of restructured muscle products is well known to be strongly affected by various salts. In the present work the effects of NaCl and CaCl2 on the ultrastructure of both fresh and cooking salted silvercarp (Hypophthalmichthys molitrix) muscle were examined, in order to elucidate the heat-initiated binding phenomenon. Sodium chloride at 0.3 and 1.5% caused swelling and fusion of the myofibrils and loss of arrayed structure. Calcium chloride at all the tested concentrations resulted in shrinkage of myofibrils, The present study demonstrated two main effects of salts on the ultrastructure of fish muscles: (i) swelling of myofibrils which, at …

Current Concepts Of Muscle Ultrastructure With Emphasis On Z-Line Architecture, M. Yamaguchi, H. Kamisoyama, S. Nada, S. Yamano, M. Izumimoto, Y. Hirai, R. G. Cassens, H. Nasu, M. Muguruma, T. Fukazawa

Food Structure

Invertebrate striated muscle, the Z-line, which defines the sarcomere length, presents diverse structural patterns both in cross section and in longitudinal section. Conflicting models have been proposed to explain the microscopic observations. The protein composition of the Z- line structure is unresolved. o: -Actin in is widely accepted as a Z-line component, and actin filaments extend into wide Z-lines. Based on recent findings from our laboratory and others, we developed a new model applicable to wide and narrow Z-lines. The model allowed the observed ultrastructural patterns of Z-lines to be simulated. Improved electron microscopic techniques should allow further progress to …

Ultrastructural Studies On The Cultivation Processes And Growth And Development Of The Cultivated Mushroom Agaricus Bisporus, D. A. Wood, G. D. Craig, P. T. Atkey, R. J. Newsam, K. Gull

Food Structure

Scanning electron microscopy (SEM) , transmission electron microscopy and light microscopy have been used to study various processes in the cultivation of the edible mushroom Agaricus bisporus . Mushrooms are cultured on composted wheat straw. The microbial degradation processes during composting have been visualised by TEM and SEM and correlated with microbiological studies . Various modes of attack by the microorganisms on the plant cell walls can be seen. Most rapid degradation occurred on the cuticle and phloem and spread to other cell types. Microbial attack was found to be nonuniform between tissue types and individual cells. The mycelium of …

Ultrastructural And Biochemical Investigations Of Mature Human Milk, Robert J. Carroll, Jay J. Basch, John G. Phillips, Harold M. Farrell Jr.

Food Structure

The casein complexes (casein micelles) of human skim milk were evaluated by electron microscopy. Fourteen samples of human milk were obtained from seven donors whose stage of lactation varied from 1 to 23 months. Compositional and biochemical parameters were measured to evaluate the nature of these samples. For mature human milks, 2-13 months of lactation, average percentage of solids-notfat was found to be 8.32 ± 0.16. Protein compositions of the skim milks were studied by the Coomassie blue dye binding method and by SDS-gel electrophoresis; total protein and casein were found to be 0.62 ± 0.18 and 0.29 ± 0.02 …

Effect Of Ionizing Irradiation And Storage On Mushroom Ultrastructure. I. The Gills Of Agaricus Bisporus (Lge.) Imbach And Pleurotus Ostreatus (Jacq. Ex Fr.) Kummer, A. Keresztes, J. Kovacs, E. Kovacs

Food Structure

We have investigated the gills of both the control and gamma-irradiated groups of A.bisporus and P.ostreatus (2.5 kGy or 2.5 and 5.0 kGy doses, respectively) by scanning (SEM) and transmission (TEM) electron microscopy. The primary aim of our study was to see, how gamma-irradiation used for shelflife extension inhibits spore production. We have found in both species that inhibition of spore production in irradiated specimens is caused by the destroying of basidia rather than by retarding normal spore development. In P.ostreatus the hymenium appears to be more sensitive to irradiation than in A.bisporus. In both species the subhymenium and trama …

Effect Of High Hydrostatic Pressure On Meat Microstructure, E. A. Elgasim, W. H. Kennick

Food Structure

Bovine longissimus muscle was prerigor pressure treated at 103.5 MNm- 2 at 37 °C for 2 min and immediately sampled, fixed and examined by light microscopy, scanning and transmission electron microscopy. Parameters like pH, Warner-Bratzler shear force values and sarcomere length were measured and related to the microscopic observations. Pressure treated samples have shorter sarcomere length, lower pH and W-B values. Physical changes include separation of sarcolemmal and endomysial sheath, contraction bands, disruption of myofibrillar structure and increased interfibrillar and intermyofibrillar spaces. At the subcellular levels, disappearance of glycogen granules, appearance of swollen mitochondria, sarcoplasmic reticulum and in some cases …