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A nutritional evaluation and optimisation of infant foods using microencapsulation

A nutritional evaluation and optimisation of infant foods using microencapsulation

Loughrill, Emma Sarah (2015) A nutritional evaluation and optimisation of infant foods using microencapsulation. PhD thesis, University of Greenwich.

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Over recent decades the modern lifestyle dynamic has led to an increased parental reliance on commercially marketed complementary infant foods in the UK, which has been highlighted by the Diet and Nutrition Survey of Infants and Young Children. The current nutritional labelling formats for ready-to-eat complementary infant foods are a duplicate of the legislative requirements for manufacturing of ready meals, intended for the general population, the implication of this is that a number of important nutrients maybe limiting or excessive, which will affect their nutritional quality and suitability as an infant food. Furthermore nutritional databases, such as McCance and Widdowson provide limited data on the composition of these types of food products. The European Food Safety Authority has highlighted that nutrient intake data after six months of life is currently inadequate as well as insufficient and urgently needs to be addressed. Therefore the nutritional content of these food products needs to be assessed to ascertain whether or not infants are meeting dietary requirements when consuming such products.

The aims of this study were to evaluate the nutritional suitability of infant food products currently available on the UK market, according to the most up to date recommendations and recent relevant legislation and to explore the microencapsulation of docasahexaenoic acid (DHA) to optimise the nutrient content of infant food products.

New protocols were developed for the quantitative analysis of certain key nutrients including High Pressure Liquid Chromatography (HPLC) – Charged Aerosol Detection for essential fatty acids, HPLC and UV spectrophotometry for fat soluble vitamins A and E, competitive enzyme immunoassay (Vitakit D™) for vitamin D and Inductively Coupled Plasma Optical Emission Spectroscopy for essential elements (Ca, Cu, Fe, K, Mg, Na, P and Zn) in commercial infant foods in the UK. The estimated daily intakes of these products were compared against current dietary recommendations for infants. In addition the Ca:P ratio was also determined in a range of commercial infant foods and compared with recommendations in relation to bone health. Furthermore, the effects of commonly practiced re-heating treatments used by parents were examined to establish whether different preparation methods affected the fatty acid content of manufactured infant formula milks. Finally, through the nutritional evaluation of these infant food products, the infant’s diet was found to be low in DHA, which provided opportunities for scope and product optimisation to improve the nutritive value of infant food products. Therefore microencapsulation of DHA was explored as a potential way to improve the nutritional quality of infant food products.

The nutritional evaluation of the essential fatty acid content of a 6-9 month old infant’s diet highlighted that pre-formed long chain polyunsaturated fatty acids (LCPUFA) DHA and arachidonic acid (AA) intakes (at 23.3 mg/day and 36.7 mg/day, respectively) were below recommendations set by the US, at 103.3 mg/day and 147.5 mg/day, respectively. This provides scope for product optimization to improve the nutritive value of commercial infant food products. With respect to the precursor essential fatty acids, the dietary intake of the n-6 fatty acid linoleic acid (LA) was found to be above recommendations at 3147.9 mg/day, whereas the n-3 fatty acid α-linolenic acid (ALA) was found to be below recommendations at 296.4 mg/day, which increases the LA:ALA ratio of the diet; this may have implications for allergy. As the fortified infant formula was identified as the major dietary contributor and due to the fact that unsaturated fatty acids are prone to oxidation, the impact of re-heating treatments used by parents on the fatty acid content of formula milk was investigated and a degree of statistically significant changes were observed. In relation to the transparency of the nutritional information declared on the labels by the manufacturers, infant formula milks were all within the limits of EU regulations although there was a degree of significant variation between the quantitative values analyzed in this study and the declared values on the labels.

With regards to the vitamin A and E analysis, normal phase HPLC was employed for the simultaneous quantification of retinyl acetate, retinyl palmitate, α-tocopherol and γ-tocopherol; reverse phase HPLC was used for the quantification of β-carotene and UV spectrophotometry for the quantification of carotenoids from selected meat and vegetable ‘ready-to-feed’ commercial infant meals. Based on the results of the study, the estimated total daily intake for a 6-9 month old infant of vitamin A (retinol equivalents, RE) and vitamin E (α-tocopherol equivalents, ATE) from both infant food and formula milk were 1.74 mg RE/day and 10.4 mg ATE/day, respectively. These intakes exceed the recommendations set by the Department of Health (1991). The main dietary contributor was highlighted as being the fortified infant formula which highlights the importance of nutrient dense foods in situations where infant formula is reduced or compromised.

The study into the essential elemental content of dairy based commercial infant food products found that the Ca:P ratio of a 7-12 month old infant’s diet was 1.49:1, which was within the recommended range of 1-2:1. However, the level of intake for each of the elements analyzed, with the exception of sodium, were found to be above the Recommended Nutrient Intake (RNI) set by the Department of Health (1991), which warrants further investigation in relation to both micronutrient interactions, and in situations where the intake of fortified infant formula milk is compromised. In addition, as this study was the first to include consumption of infant snack products, the level of total calorie intake was also assessed, which indicated that energy intakes exceed recommendations set by the Scientific Advisory Committee of Nutrition (2011) by 42%, which may have implications for obesity. This highlights that parents need to select appropriate snack products. In relation to bone health, vitamin D was also quantified in a range of commercial infant meals. The total dietary intake of vitamin D3 was determined to be 9.61 μg/day, which is 137% higher than the RNI set by the Department of Health (1991) for 7-12 month old infants. However 120% is contributed from fortified infant formula, which may raise a cause for concern over deficiency issues, in situations where infant formula is reduced or compromised or the infant is breastfed. Furthermore the National Diet and Nutrition Survey have shown evidence for an increased risk of vitamin D deficiency in all age and sex groups in the UK.

Consequently, following the nutritional evaluation of commercial infant food products, an infant’s diet is not meeting recommendations for the pre-formed long chain polyunsaturated fatty acids, DHA and AA. DHA may be of more significance due to endogenous production. Therefore, two approaches have been explored for the encapsulation of DHA in the pH dependent polymer hydroxypropyl methylcellulose acetate succinate (HPMCAS). In the first approach direct spray drying was implemented for the microencapsulation of DHA/HPMCAS organic solutions, while in the second approach solid lipid nano-emulsions of DHA, produced by high pressure homogenization, were subsequently spray dried in HPMCAS aqueous solutions. The direct spray drying approach resulted in significantly higher quantities of DHA being encapsulated, at 2.09 g/100 g compared to 0.60 g/100 in the spray dried solid lipid nano-emulsions. DHA stability was increased by the direct spray drying approach and the release of DHA was analysed by a dissolution methodology. The encapsulated powders produced by the desired method offer a source of DHA that has the potential to be incorporated into infant foods to increase their dietary DHA consumption.

Item Type: Thesis (PhD)
Additional Information:
Uncontrolled Keywords: Infant feeding; infant foods; microencapsulation; nutritional content of infant foods;
Subjects: R Medicine > RM Therapeutics. Pharmacology
Faculty / School / Research Centre / Research Group: Faculty of Engineering & Science
Faculty of Engineering & Science > School of Science (SCI)
Last Modified: 07 Jan 2019 10:10

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