Variability of micronutrient content in enriched dairy and fruit products

Abstract

Accurate measures of micronutrient levels in newly developed enriched foods are indispensable for valid labelling, for determination of ultimate levels for possible claimed health effects and for safety. To date, only a limited amount of public literature is available on the reproducibility of laboratory analysis and on the similarity within novel fortified or enriched foods. Within the framework of an intervention trial in frail elderly, the micronutrient content of eight different types of enriched foods were repeatedly examined. The variance in concentrations of the vitamins B 1, B 2, B 6, folic acid, B 12, C, D, and E was studied, in addition to levels of the minerals zinc, iodine, calcium, iron and magnesium. Four main factors, possibly contributing to the variability of these micronutrient levels, were investigated: (1) type of product, (2) type of laboratory (between-laboratory reproducibility), (3) time of the year (month) in which analyses were carried out (May–October) and (4) freshness of the product. The type of product and laboratory emerged as factors contributing mostly to the total variability in concentrations of vitamins (on average ~50% explained). However, none of the products consistently contained higher or lower levels compared to the other products and most target levels were met except for vitamin B 2 in both dairy and fruit products and for folic acid and vitamin C in some fruit products. Differences between products were regarded as acceptable. Extensive evaluation of multiple lab results should be emphasised within the manufacturing process of enriched foods.