Effect of cooling rate and super-chilling temperature on ice crystal characteristic, cell structure, and physicochemical quality of super-chilled fresh-cut celery

2020 ◽  
Vol 113 ◽  
pp. 249-255 ◽  
Author(s):  
Cong-Cong Xu ◽  
De-Kun Liu ◽  
Chun-Xiao Guo ◽  
Yu-qing Wu
2019 ◽  
Vol 37 (2) ◽  
pp. 13-19
Author(s):  
Paula Cristina Carvalho Lima ◽  
Bianca Sarzi de Souza ◽  
Selina Fyfe

HortScience ◽  
2012 ◽  
Vol 47 (3) ◽  
pp. 382-385 ◽  
Author(s):  
Yukari Murakami ◽  
Yoshihiko Ozaki ◽  
Hidemi Izumi

Enzymatic peeling of ‘Fuyu’ and ‘Tone-wase’ persimmon fruit was conducted for production of fresh-cut slices, and the microbiological and physicochemical quality of enzyme-peeled fresh-cut slices was compared with that of slices manually peeled with a knife. The enzymatic peeling process involved a porous treatment of the peel, heating at 100 °C for 45 s, infusion with 3% protopectinase at 37 °C for 3 h, and rinsing under running tap water. Initially, the peel of ‘Fuyu’ persimmon fruit had microbial counts ranging from 3.9 to 4.2 log cfu·g−1 and a diverse microflora. The heating treatment before the enzymatic peeling process reduced the microbial counts in both the peel and flesh of all fruits to levels below the lower limit of detection. After the enzyme infusion followed by gentle rinsing with tap water, microbial counts of enzyme-peeled fruit were close to or below the level of detection. When microbial contamination of enzyme-peeled and knife-peeled ‘Fuyu’ and ‘Tone-wase’ persimmon slices was compared, the bacterial counts and diversity of bacterial and fungal flora were less in enzyme-peeled slices than in knife-peeled slices. With ‘Tone-wase’ slices, the color index, pH, and texture were unaffected by enzymatic peeling, except for surface lightness, which was lower in enzyme-peeled slices than in knife-peeled slices. These results indicate that enzymatic peeling could be an alternative to knife-peeling of ‘Tone-wase’ persimmon fruit for fresh-cut production from the point of microbiological and physicochemical quality.


2011 ◽  
Vol 28 (1) ◽  
pp. 59-66 ◽  
Author(s):  
Isabel Alegre ◽  
Inmaculada Viñas ◽  
Josep Usall ◽  
Marina Anguera ◽  
Maribel Abadias

Author(s):  
Marek Malecki ◽  
James Pawley ◽  
Hans Ris

The ultrastructure of cells suspended in physiological fluids or cell culture media can only be studied if the living processes are stopped while the cells remain in suspension. Attachment of living cells to carrier surfaces to facilitate further processing for electron microscopy produces a rapid reorganization of cell structure eradicating most traces of the structures present when the cells were in suspension. The structure of cells in suspension can be immobilized by either chemical fixation or, much faster, by rapid freezing (cryo-immobilization). The fixation speed is particularly important in studies of cell surface reorganization over time. High pressure freezing provides conditions where specimens up to 500μm thick can be frozen in milliseconds without ice crystal damage. This volume is sufficient for cells to remain in suspension until frozen. However, special procedures are needed to assure that the unattached cells are not lost during subsequent processing for LVSEM or HVEM using freeze-substitution or freeze drying. We recently developed such a procedure.


Author(s):  
William P. Sharp ◽  
Robert W. Roberson

The aim of ultrastructural investigation is to analyze cell architecture and relate a functional role(s) to cell components. It is known that aqueous chemical fixation requires seconds to minutes to penetrate and stabilize cell structure which may result in structural artifacts. The use of ultralow temperatures to fix and prepare specimens, however, leads to a much improved preservation of the cell’s living state. A critical limitation of conventional cryofixation methods (i.e., propane-jet freezing, cold-metal slamming, plunge-freezing) is that only a 10 to 40 μm thick surface layer of cells can be frozen without distorting ice crystal formation. This problem can be allayed by freezing samples under about 2100 bar of hydrostatic pressure which suppresses the formation of ice nuclei and their rate of growth. Thus, 0.6 mm thick samples with a total volume of 1 mm3 can be frozen without ice crystal damage. The purpose of this study is to describe the cellular details and identify potential artifacts in root tissue of barley (Hordeum vulgari L.) and leaf tissue of brome grass (Bromus mollis L.) fixed and prepared by high-pressure freezing (HPF) and freeze substitution (FS) techniques.


Author(s):  
Siti Zaharah Rosli ◽  
Mohd Adzahan Noranizan ◽  
Son Radu ◽  
Roselina Karim ◽  
Noraniza Mohd Adzahan ◽  
...  

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