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Paper Information

Journal:   ELECTRONIC JOURNAL OF FOOD PROCESSING AND PRESERVATION   2017 , Volume 8 , Number 2 ; Page(s) 107 To 122.
 
Paper: 

EFFECT OF SUCROSE CONCENTRATION ON RHEOLOGICAL PROPERTIES OF POMEGRANATE JUICE GELS BASED ON GELATIN/?-CARRAGEENAN

 
 
Author(s):  MOTAMEDZADEGAN A., SAHRAEI S.*, SARABI AGHDAM V.
 
* SARI AGRICULTURAL SCIENCES AND NATURAL RESOURCES UNIVERSITY SARI, MAZANDARAN, IRAN
 
Abstract: 

Background and objectives: In this paper local pomegranate juice (50% v/v final solution) based gels made from gelatin or kappa-carrageenan with sucrose (2.6%, 5.8% w/v final solution) have been examined to determine their textural characteristics and viscoelastic properties. Pomegranate is one of the most important crops cultivated in Iran which extensively used as a source of variety of products. However, some especial properties of this fruit such as low pH, varied tastes, red color, and phenolic and anthocyanin compounds may affect final product properties. In this regard, it is required to study the influence of applying natural pomegranate juice on final gel quality. Since gelatin and kappa-carrageenan are two popular examples of protein and polysaccharide hydrocolloids which are available with low cost, in this work pomegranate gels were prepared based on these hydrocolloids. Generally, gel formulations include sugar as a taste and texture improver so its interaction with gel components and its effect on textural properties of pomegranate gel was investigated.
Materials and methods: In order to determine textural properties like hardness, cohesiveness and springiness, texture profile analyses have been used. Also, to investigate viscoelastic properties, dynamic oscillation measurements were used and their rheological behavior was interpreted regard to loss tangent, elastic and viscos modulus.
Results: The result of texture profile analysis show that incorporation of sucrose into gelatin based gels effectively increases hardness, cohesiveness and springiness. Furthermore, the results of oscillatory dynamic rheological measurements show that gelatin gels are more elastic and resist higher frequencies when sucrose concentration increased. Since gelatin has the protein nature, it has different electrostatic charges at different pH levels, so at lower/higher pH than pI it would be found with positive/negative charge. Accordingly, under acidic condition of pomegranate juice with pH lower than gelatin pI, gelatin may carry positive charge which able it interact with anionic agents in the media. In this case, presence of phenolic compounds, flavonoids and tannins with anionic nature in pomegranate juice can enhance these interactions. The results of our investigations have shown that applying pomegranate juice and sucrose for the preparation of gelatin gels leads to form a high quality gel due to proper pH of the juice and adequate hydrogen and electrostatic interactions. In case of ?-carrageenan gels, increase in the sucrose level enhances viscose modulus and decrease hardness and cohesiveness because of preventing the formation of a solid-like viscoelastic texture. Although low concentration of sucrose can improve gel textural properties, at high concentration it inversely affects on carrageenan gel elasticity. The major reason for this effect may be due to sucrose prohibition from cross-linking interactions. Moreover, different compounds in pomegranate juice may have synergistic effect on decreasing textural quality of carrageenan gels by sucrose.
Conclusion: The results of this study indicate that high quality pomegranate gels based on gelatin and ?-carrageenan with optimum concentration of sucrose can be produced with no adverse effects of natural conditions of pomegranate juice (low pH and contained ions) on the quality.

 
Keyword(s): POMEGRANATE JUICE, RHEOLOGY, GELATIN, KAPPA-CARRAGEENAN, GGEL
 
 
References: 
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Citations: 
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APA: Copy

MOTAMEDZADEGAN, A., & SAHRAEI, S., & SARABI AGHDAM, V. (2017). EFFECT OF SUCROSE CONCENTRATION ON RHEOLOGICAL PROPERTIES OF POMEGRANATE JUICE GELS BASED ON GELATIN/?-CARRAGEENAN. ELECTRONIC JOURNAL OF FOOD PROCESSING AND PRESERVATION, 8(2 ), 107-122. https://www.sid.ir/en/journal/ViewPaper.aspx?id=569870



Vancouver: Copy

MOTAMEDZADEGAN A., SAHRAEI S., SARABI AGHDAM V.. EFFECT OF SUCROSE CONCENTRATION ON RHEOLOGICAL PROPERTIES OF POMEGRANATE JUICE GELS BASED ON GELATIN/?-CARRAGEENAN. ELECTRONIC JOURNAL OF FOOD PROCESSING AND PRESERVATION. 2017 [cited 2021August02];8(2 ):107-122. Available from: https://www.sid.ir/en/journal/ViewPaper.aspx?id=569870



IEEE: Copy

MOTAMEDZADEGAN, A., SAHRAEI, S., SARABI AGHDAM, V., 2017. EFFECT OF SUCROSE CONCENTRATION ON RHEOLOGICAL PROPERTIES OF POMEGRANATE JUICE GELS BASED ON GELATIN/?-CARRAGEENAN. ELECTRONIC JOURNAL OF FOOD PROCESSING AND PRESERVATION, [online] 8(2 ), pp.107-122. Available: https://www.sid.ir/en/journal/ViewPaper.aspx?id=569870.



 
 
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