Analysis and stability of microencapsulated folic acid during the processing and preparation of instant Asian noodles

Hau, R 2008, Analysis and stability of microencapsulated folic acid during the processing and preparation of instant Asian noodles, Doctor of Philosophy (PhD), Applied Sciences, RMIT University.

Document type: Thesis
Collection: Theses

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Title Analysis and stability of microencapsulated folic acid during the processing and preparation of instant Asian noodles
Author(s) Hau, R
Year 2008
Abstract Fortification of instant Asian noodles with folic acid has the potential to enhance dietary folate intakes. Recent studies show folate deficiency is prevalent in many countries. Furthermore, this vitamin is unstable upon exposure to light, air, heat and extreme conditions of acidity and alkalinity. Internationally, folate in foods has traditionally been analysed by a microbiological assay, however, due to the extensive time required for sample preparation and analysis, alternative procedures for analysis require consideration.

The aims of the current study have been to investigate the stability of added folic acid in fortified instant fried noodles by analytical methods of capillary electrophoresis and reversed-phase HPLC. Additionally, procedures for the microencapsulation of folic acid by spray drying have been evaluated along with their significance in increasing the stability of the vitamin during processing and boiling of instant noodles.

Optimisation of capillary electrophoretic conditions showed that the maximum response of folic acid relative to an internal standard was achieved using various concentrations of phosphate and borate. Analytical parameters including the effects of pH, voltage and temperature were studied along with enzymatic treatments for liberation of folic acid from the noodle matrix based. Higher recoveries were obtained using the enzymes however these exceeded 100% due to sample matrix interference. Standard addition or internal calibration were both effective in correcting for matrix interferences.

Comparative investigations with reversed-phase HPLC confirmed the results obtained with the capillary electrophoresis. Using either a phosphate based buffer in conjunction with an ion-pairing agent at alkaline pH or an acidic mobile phase, the results attained were in good agreement as folic acid exhibited excellent stability under typical processing conditions.

Various food approved hydrocolloids were evaluated for encapsulation of folic acid by spray drying. Incorporation of the microcapsules into formulations of instant fried noodles showed that after boiling the folic acid was chemically degraded to some extent and leaching also occurred. The microcapsules exhibited similar properties regardless of the binding agent used, with losses still occurring during the boiling stage. In order to enhance the structural integrity of the spray dried microcapsules, CaCl2 was used as a cross-linking agent for capsules prepared using alginate or pectin binding agents. Considerable increases in retention of core material were observed as the network exhibited a reduction in swelling and hydration, and subsequently a decrease in the release of folic acid.

In summary, capillary electrophoresis and reversed-phase HPLC provided excellent separation and good quantitatation of added folic acid in instant Asian noodles. Excellent resolution was obtained between the sample matrix interference of instant noodles and the analysed vitamin. Folic acid displayed high stability throughout the processing of instant noodles whereas there was consistent evidence that unencapsulated folic acid was degraded during boiling. Microencapsulation of folic acid with combinations of alginate and pectin as the binding agents, proved to be effective in maintaining folic acid stability when calcium treatment was performed after spray drying. These findings provide an effective way to retain folic acid used in fortifying Asian instant noodles.
Degree Doctor of Philosophy (PhD)
Institution RMIT University
School, Department or Centre Applied Sciences
Keyword(s) Folic acid in human nutrition
Food additives -- Analysis
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