Effects of different freezing methods on the quality and microstructure of lotus (Nelumbo nucifera) root
- Authors: Tu, Jing , Zhang, Min , Xu, Baoguo , Liu, Huihua
- Date: 2015
- Type: Text , Journal article
- Relation: International Journal of Refrigeration Vol. 52, no. (2015), p. 59-65
- Full Text: false
- Reviewed:
- Description: The effects of three freezing methods, air blast freezing (ABF), immersion freezing (IF) and ultrasound-assisted immersion freezing (UIF), on quality and microstructure of lotus roots were investigated. The parameters used to evaluate the freezing methods effect were the freezing time, color, firmness, drip loss, vitamin C and microstructure of the final frozen products. The results showed that the UIF products had several advantages in terms of the freezing time, color, firmness and drip loss over ABF and IF. No significant difference (p > 0.05) of vitamin C content was observed between the ABF and IF products, while significant difference (p < 0.05) of vitamin C was observed between UIF and ABF/IF products. ABF caused the largest destruction to the tissue, while the microstructure of the UIF products was the best preserved. It is concluded that UIF processing was a better freezing method for lotus root with improved quality and less damaged microstructure than the two other methods. © 2014 Elsevier Ltd and IIR.
Effect of physicochemical properties on freezing suitability of Lotus (Nelumbo nucifera) root
- Authors: Tu, Jing , Zhang, Min , Xu, Baoguo , Liu, Amy
- Date: 2015
- Type: Text , Journal article
- Relation: International Journal of Refrigeration Vol. 50, no. (2015), p. 1-9
- Full Text: false
- Reviewed:
- Description: The initial physicochemical properties of different lotus roots were studied with the aim to evaluate their influence on freezing suitability. Six physicochemical properties indicators (starch content, whiteness index, maximum diameter, protein amount, titratable acidity and vitamin C) of lotus root were determined by principal component analysis. It was observed from the experimental results that the initial physicochemical properties of lotus root can directly affect the freezing suitability in terms of initial freezing temperature, transition phase time, total freezing time, relative firmness and drip loss. Correlation analysis suggested that relative firmness increases in proportion to starch content, and initial freezing temperature and drip loss are inversely proportional to the starch content. Compared to immersion freezing, power ultrasound can significantly improve the freezing rate and relative firmness but decrease drip loss. These results suggested that high quality frozen lotus root can be achieved via appropriately selecting high starch content lotus root and using ultrasound-assisted immersion freezing.
Research trends in selected blanching pretreatments and quick freezing technologies as applied in fruits and vegetables : A review
- Authors: Xin, Ying , Zhang, Min , Xu, Baoguo , Adhikari, Benu , Sun, Jincai
- Date: 2015
- Type: Text , Journal article
- Relation: International Journal of Refrigeration Vol. 57, no. (2015), p. 11-25
- Full Text: false
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- Description: Abstract This paper presents a comprehensive review of recent developments in thermal (radio frequency, microwave and ohmic), non-thermal (high pressure, ultrasound and infrared) methods in blanching pretreatment. Recent developments in quick freezing technology (high pressure, dehydrofreezing and ultrasound-assisted) as applied to freezing of fruits and vegetables are also reviewed. The thermal and non-thermal blanching methods provide rapid and uniform heating; reduce the loss of soluble nutrients and minimize thermal damage compared to conventional hot water blanching. High pressure freezing seems to promote instantaneous and homogeneous ice nucleation in fruits and vegetables. Dehydrofreezing is capable of reducing the damage to plant texture by removal partial of water before freezing. Ultrasound-assisted freezing is found to be effective in the initiation of nuclei and subsequent growth of crystals. More fundamental researches are needed for better design and scale up, so that these technologies can be transferred from laboratory to industry. © 2015 Elsevier Ltd and IIR.