| 1. |
- Chambale, Borges, et al.
(author)
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Coconut Press Cake Alkaline Extract—Protein Solubility and Emulsification Properties
- 2013
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In: Food and Nutrition Sciences. - 2157-9458. ; 4:9B, s. 29-37
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Journal article (peer-reviewed)abstract
- The solubility and the emulsification properties of a crude freeze dried alkaline protein extract (APE), 30% protein, obtained from coconut milk press cake by one step extraction at pH 11, were characterized at pH 2 to 11, and the cream and subnatant fractions of the emulsion studied by SDS-PAGE electrophoresis. The protein solubility followed U profile, showing a minimum at pH 3 to 4, close to but not identical to reported iso-electric points of 4 - 5 for many coconut protein fractions. The extract showed good capacity to form oil-in-water emulsion outside the low solubility pH range. The bands that appeared to play a role in the emulsification were found at 32 and 42 kDa in SDS-PAGE electrophoresis, but the most predominant absorbed band was at 23 kDa.
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| 2. |
- Chambale, Borges
(author)
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Exploring the functionality of coconut proteins
- 2015
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Doctoral thesis (other academic/artistic)abstract
- At present, coconut proteins are discarded as a waste product by the coconut oil industry. If the range of applications of coconut proteins is to be expanded, their potential functionalities should be investigated. Emulsions and gels are of the greatest interest in food industry. Today the dry processing of copra at elevated temperatures is used to optimize the oil recovery. The functionalities of proteins in food are mainly determined by their structure and physicochemical properties, such as amino acid composition and sequence, protein size and conformation, physical and thermal stability, solubility and surface hydrophobicity. The harsh treatment leads to denaturation and loss of protein solubility and functionality. Wet processing is an alternative method that may yield functional proteins in addition to oil. To explore the functionalities of coconut proteins, protein fractions were obtained using the wet processing method and analysed for molecular size and isoelectric points in electrophoresis, amino acid sequencing from mass spectrometry and also for their capacity to emulsify and stabilise oil-in-water emulsions. The results showed minimum solubility at pH 3-4, increasing in both sides of the minimum, exhibiting a V-shaped profile. Mass spectrometry and protein fingerprint did not produce conclusive results, as coconut proteomes have not been sequenced and entered in the databases. Protein mapping only matched partially to glutelin OS, tr|Q9SNZ2|Q9SNZ2_ELAGV and 7S globulin, tr|Q9AU64|Q9AU64_ELAGV from oil palm, a cultivar close to Cocos nucifera. SDS-PAGE showed results close to those already reported, especially for the skim coconut milk proteins. The insoluble protein resolved at 32 and 21 kDa, which correlates closely to the 11S globulin or cocosin, the major coconut globulin protein. Native coconut proteins were not able to efficiently emulsify and stabilise oil in water emulsion. The droplets were large (13 µm) and high-pressure homogenisation only reduced the droplets size down to 3-5 µm, still not sufficiently small to prevent destabilisation. Flocculation and creaming were the predominant mechanisms of destabilisation. However, under heating to protein denaturation, at 95°C and homogenisation, concentrated coconut milk (40% fat) demonstrated improved physical stability due to formation of a colloidal glass structure. Coconut protein also demonstrated the ability to form gels with appreciable elastic modulus (G’ > 1000 Pa), but only in neutral to alkaline environments. The study shows that colloidal glass and gelation are functional properties of coconut proteins that may lead to novel products and potentially of the greater use.
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| 3. |
- Chambale, Borges, et al.
(author)
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Heat Induced Gels from Coconut Press Cake Proteins
- 2014
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In: Food and Nutrition Sciences. - : Scientific Research Publishing, Inc.. - 2157-9458 .- 2157-944X. ; 5:6, s. 562-570
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Journal article (peer-reviewed)abstract
- Freeze-dried coconut press cake powder (CPP), 43% w/w protein, was used to investigate the heat-induced gelation by heating in rheometer to 75℃ in a wide range of pH values, from 4 to 9. Low strain oscillatory method applied the measure visco-elastic propertieson 15% w/w CPP. The gel strength was also assessed by a texture analyzer. SDS-PAGE electrophoresis was conducted to identify the proteins evolved in the gel network structure and the gel micro-structure was also evaluated. At low pH, the CPP proteins formed soft (elastic modulus <100 Pa) particulate gels prone to syneresis, with aggregate size of the order of 4.2 micrometers. In the alkaline region, homogenous gels were induced by heating. Gel strength started to increase dramatically from 64℃ to 67℃, for pH 9 and pH 8 respectively, reaching the maximum gel elastic modulus over 1000 Pa at pH 9. The SDS-PAGE showed that the polypeptide sub-unities at 24, 32 - 34 and 53 kDa were the most prominent in gelation.
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