Influence of simultaneous variations in temperature and relative humidity on chemical stability of two vitamin C forms and implications for shelf life models.

Vitamin C powder ingredients are popular food fortificants and are among the most commonly added nutrients. While information on degradation kinetics and shelf life of vitamin C exists, current models are limited in their applicability to systems where relative humidity (RH) and temperature are varied simultaneously, and where phase transformations occur. This study monitored stability of two forms of vitamin C (sodium ascorbate and ascorbic acid) under various RH and temperature conditions. Vitamin C was measured colorimetrically, and stability data were used to improve understanding of vitamin C shelf life when deliquescence occurs during storage. RH and temperature both significantly impacted vitamin stability, though RH had a larger effect. Vitamin dissolution preceded extensive degradation and was found to be a good predictor of vitamin C loss. This research highlights the importance of considering phase transformations when constructing shelf life models and maintaining vitamin C in the solid state for enhanced stability.

Melamine detection in infant formula powder using near- and mid-infrared spectroscopy.

Near- and mid-infrared spectroscopy methods (NIR, FTIR-ATR, FTIR-DRIFT) were evaluated for the detection and quantification of melamine in infant formula powder. Partial least-squares (PLS) models were established for correlating spectral data to melamine concentration: R(2) > 0.99, RMSECV ≤ 0.9, and RPD ≥ 12. Factorization analysis of spectra was able to differentiate unadulterated infant formula powder from samples containing 1 ppm melamine with no misclassifications, a confidence level of 99.99%, and selectivity > 2. These nondestructive methods require little or no sample preparation. The NIR method has an assay time of 1 min, and a 2 min total time to detection. The FTIR methods require up to 5 min for melamine detection. Therefore, NIR and FTIR methods enable rapid detection of 1 ppm melamine in infant formula powder.

Impact of deliquescence on the chemical stability of vitamins B1, B6, and C in powder blends.

Single vitamin ingredients and blends in premixes are widely used in the food and supplement industries and are predominantly in powder form. To meet label claims and/or determine appropriate overages, it is important to characterize the stability of these ingredients. Although moisture is a known promoter of instability in powder blends, the combined effects of storage relative humidity (RH), formulation, and deliquescence on the stability of these systems are not well-characterized. The objective of this study was to determine the effect of deliquescence on the stability of vitamins B 1, B 6, and C and their mixtures. Deliquescence points (RH 0s) for all formulations were determined by moisture sorption analysis. Single, binary, ternary, and quaternary mixtures of thiamin HCl, pyridoxine HCl, sodium ascorbate, and fructose were stored in RH-controlled environmental chambers between 43 and 98% RH at 22 degrees C for up to 12 weeks. Vitamin stability was determined by high-performance liquid chromatography (HPLC). Formulation and storage RH significantly affected vitamin stability. Thiamin and ascorbate degradation were significantly promoted above the RH 0, while pyridoxine was least affected by storage RH. The deliquescence lowering phenomenon enhanced moisture sorption of blends at RHs below the RH 0s. Ascorbate enhanced thiamin degradation. Therefore, formulation, storage conditions, and the relation of these to deliquescence points may affect the shelf life, quality, and functionality of vitamin blends and should be considered in product development, processing, storage, and use.