Improvement of Freezing Quality of Food by Pre-Dehydration With Microwave-Vacuum Drying

2007 ◽  
Author(s):  
Nurkholis Hamidi ◽  
Takaharu Tsuruta
Keyword(s):  
Freezing Point ◽  
Vacuum Drying ◽  
Freezing And Thawing ◽  
Microwave Vacuum Drying ◽  
Partial Dehydration ◽  
Chamber Temperature ◽  
Quality Of Food ◽  
Pre Treatment ◽  
Freezing Chamber

Partial dehydration through microwave vacuum drying has been applied to tuna, oyster and mackerel before freezing in order to reduce quality damages upon freezing and thawing. Samples were subjected to microwave vacuum drying at pressure of 4 kPa and temperature less than 25°C in order to remove some water from the samples. Two freezing conditions, freezing chamber temperature at −20°C and −80°C, were used in this experiment. The experimental results showed that decreasing the water content in tuna could lower the freezing point temperature and made the freezing time become shorter. It was also found that removing some water in oyster and mackerel was effective to minimize the drip loss. After thawing, the pre-dehydrated mackerel showed better microstructure than mackerel that frozen without pre-treatment. Furthermore, good scores were given by a group of panelist in the evaluation on aroma, flavor, and general acceptability of mackerel that subjected to the pre-treatment.

The Effect of Microwave Vacuum Drying on the Quality of Tiegun yam

2012 ◽  
Author(s):  
Zhihuai Mao ◽  
Dong Li ◽  
Guangyue Ren ◽  
Xiaoyan Du ◽  
Wenxue Zhu
Keyword(s):  
Vacuum Drying ◽  
Microwave Vacuum Drying

Ultrasound-assisted osmotic process on quality of microwave vacuum drying sweet potato

2018 ◽  
Vol 36 (11) ◽  
pp. 1367-1379 ◽  
Author(s):  
Camel Lagnika ◽  
Jiapeng Huang ◽  
Ning Jiang ◽  
Dajing Li ◽  
Chunquan Liu ◽  
...  
Keyword(s):  
Sweet Potato ◽  
Vacuum Drying ◽  
Microwave Vacuum Drying ◽  
Ultrasound Assisted

scholarly journals Effect of Drying Methods on Physicochemical Parameters of Different Red Beetroots (Beta vulgaris L.) Species

2019 ◽  
Author(s):  
Dóra Székely ◽  
Klaudia Vidák ◽  
Diána Furulyás ◽  
Ákos Ribárszki ◽  
Mónika Stéger-Máté
Keyword(s):  
Physicochemical Parameters ◽  
Color Change ◽  
Vacuum Drying ◽  
Drying Methods ◽  
Total Polyphenol ◽  
Microwave Vacuum Drying ◽  
Hot Air ◽  
Vacuum Method ◽  
Drying Technology

The aim of this work was to study the influence of atmospheric, vacuum and microwave vacuum drying methods on the quality of dried beetroots. Three different red beetroot species ('Alto F1', 'Cylindra', 'Detroit') were chosen in this study. The microwave vacuum method reduced the total time of drying and decreased the shrinkage compared to the other drying methods. The quality of the dehydrated material was described by its color change, antioxidant capacity, total polyphenol, betacyanin, betaxanthin and each phenolic acids content. The attempts were made to suggest the microwave vacuum method for red beetroot samples as a gentle drying technology to reach a special texture that is favoured by costumers. During the experiments relevant differences could be observed between the investigated beetroot species on the effect of different drying methods. According to the examined parameters the 'Cylindra' species proved the most appropriate beetroot variety for microwave vacuum drying. Based on the results, the combined methods with hot-air at 60 °C followed by microwave vacuum finish drying was the most suitable assay to preserve the investigated parameters in the highest amount.

EFFECT OF PRECOOLING AND RATE OF FREEZING ON THE QUALITY OF DRESSED POULTRY

1938 ◽  
Vol 16d (6) ◽  
pp. 139-152 ◽  
Author(s):  
L. Sair ◽  
W. H. Cook
Keyword(s):  
Quantitative Study ◽  
Storage Time ◽  
Freezing Point ◽  
Freezing Rate ◽  
Freezing And Thawing ◽  
Constant Rate ◽  
Minced Muscle ◽  
Minced Meat ◽  
Number Of Bacteria

The rate at which poultry is frozen has been shown to have no effect on the number of bacteria present, and little, if any, effect on the extent of surface desiccation or development of visceral taint. The development of taint appears to depend primarily on the period during which the product is held at temperatures above the freezing point, and little advantage is gained by freezing promptly after slaughter, since taint development occurs during thawing.A quantitative study of the amount of fluid exuded (drip) after freezing and thawing whole birds shows that, regardless of the rate of freezing, the whole bird does not drip. Freezing does change the condition of the water in the muscle, however, since drip can be obtained from minced meat after freezing. If minced meat is frozen within 3 hours of slaughter, the amount of drip is somewhat variable but apparently independent of the rate of freezing. If the birds are stored for 24 hours or more at 0 °C., prior to freezing, the typical curved relation between the amount of drip and the freezing rate is obtained, the drip decreasing as the freezing rate increases.Using a constant rate of freezing (2.5 hours to pass from 0° to − 5 °C.), the amount of drip decreases as the storage time prior to freezing is increased. During storage at 0 °C., the greatest decrease occurs during the first day, but continues for periods up to 2 weeks. At 10 °C., little decrease occurs during the first 5 days, after which it decreases slowly until the product spoils. The amount of drip obtained at a given rate of freezing appears to be proportional to the amount of fluid obtained from the unfrozen material, showing that the drip is determined by the condition of the water in the original minced muscle. There were some indications that the state of the water in the tissue was partly determined by the pH, but the results were not conclusive.

scholarly journals Effect of Intermittent Microwave Volumetric Heating on Dehydration, Energy Consumption, Antioxidant Substances, and Sensory Qualities of Litchi Fruit during Vacuum Drying

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4291 ◽  
Author(s):  
Xiaohuang Cao ◽  
Jianping Chen ◽  
Md. Nahidul Islam ◽  
Wanxiu Xu ◽  
Saiyi Zhong
Keyword(s):  
Energy Consumption ◽  
Sensory Evaluation ◽  
Vacuum Drying ◽  
Volumetric Heating ◽  
Microwave Vacuum Drying ◽  
Sensory Qualities ◽  
Drying System ◽  
Litchi Fruit ◽  
Heating Profiles

To examine the processing characteristics and high quality of an improved microwave vacuum drying system, litchi fruits were dried using intermittent microwave volumetric heating while microwave vacuum drying at 2 W/g was carried out for comparison; the intermittent microwave heating profiles were set as (1) 5 min drying-on, 5 min drying-off; (2) 5 min drying-on, 10 min drying-off; and (3) 5 min drying-on, 15 min drying-off. Energy consumption during drying was determined, and physicochemical properties such as moisture content, vitamin C, total phenolics, color, and sensory evaluation of dried products were assessed. In microwave vacuum drying, intermittent microwave volumetric heating was found to be energy-efficient (about 32 KJ/g to 45 KJ/g) and saved at least 31% of energy consumption compared with microwave vacuum drying as well as decreasing product browning. In addition, microwave volumetric heating had no substantial effects on sugar and protein contents, while antioxidants were affected significantly (p ≤ 0.05). Moreover, sensory evaluation showed that intermittent microwave-assisted vacuum drying (IMVD) increased the acceptance of the dried product compared with microwave vacuum drying (MVD).

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