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.

Deliquescence is a first order phase transition from solid to solution that occurs at a relative humidity (RH) that is characteristic to the solid ingredient. In blends containing more than one component with deliquescent behavior, the RH of the solid-solution transition will be lowered, leading to some level of dissolution at relatively low RH conditions. Dissolution arising as a result of deliquescence will impact the chemical and physical stability of complex food systems. Because chemical reactions occur much more readily in solution, deliquescence will enhance the degradation of labile food ingredients. RH fluctuations will lead to cycles of deliquescence and efflorescence (crystallization), which will contribute to particle agglomeration and caking. This review addresses the phenomenon of deliquescence, the significance of deliquescence to the food industry, measurement techniques, the kinetics and thermodynamics of deliquescence, the behavior of mixtures of deliquescent salts (including phase diagrams and thermodynamics of binary systems), and consequences of deliquescence on chemical and physical stability of powdered food and nutritional ingredient blends.

The degradation behaviors of catechins in dilute aqueous systems, including tea beverages and catechin solutions, have been documented; however, their reaction kinetics in green tea concentrated solutions, and impacts of pH, concentration, and temperature thereon, have not yet been established. In this study, reactions were conducted at pH levels ranging from 1.5 to 7, concentrations ranging from 1 to 1666.7 mg/mL, and temperatures ranging from 25 to 120 °C. Catechin contents were determined using high-performance liquid chromatography. Catechins were found to be more stable at high concentrations around pH 4. An empirical model for catechin content was established as a function of pH and temperature and showed good correlation between green tea concentrated solutions and previous reports of catechin stability in powder systems. These results provide useful approaches for shelf life calculations and catechin loss predictions at given temperature and pH conditions in green tea concentrates.

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BackgroundCassava starch, the economically important agricultural commodity in Thailand, can readily be cast into films. However, the cassava starch film is brittle and weak, leading to inadequate mechanical properties. The properties of starch film can be improved by adding plasticizers and blending with the other biopolymers.ResultsCassava starch (5%w/v) based films plasticized with glycerol (30 g/100 g starch) were characterized with respect to the effect of carboxymethyl cellulose (CMC) concentrations (0, 10, 20, 30 and 40%w/w total solid) and relative humidity (34 and 54%RH) on the mechanical properties of the films. Additionally, intermolecular interactions were determined by Fourier transform infrared spectroscopy (FT-IR), melting temperature by differential scanning calorimetry (DSC), and morphology by scanning electron microscopy (SEM). Water solubility of the films was also determined. Increasing concentration of CMC increased tensile strength, reduced elongation at break, and decreased water solubility of the blended films. FT-IR spectra indicated intermolecular interactions between cassava starch and CMC in blended films by shifting of carboxyl (C = O) and OH groups. DSC thermograms and SEM micrographs confirmed homogeneity of cassava starch-CMC films.ConclusionThe addition of CMC to the cassava starch films increased tensile strength and reduced elongation at break of the blended films. This was ascribed to the good interaction between cassava starch and CMC. Cassava starch-CMC composite films have the potential to replace conventional packaging, and the films developed in this work are suggested to be suitable for low moisture food and pharmaceutical products.