Influence of processing and packaging conditions on probiotic survivability rate, physico-chemical and sensory characteristics of low calorie synbiotic milk beverage.

The work presented in this research communication was carried out to prepare low calorie synbiotic milk beverage by optimizing water and sugar level and to investigate the effect on its storage ability of different packaging materials (polypropylene, high impact polystyrene, high-density polyethylene and glass). Addition of both water and sugar significantly (P < 0.05) affected the viscosity, probiotic count and sensory properties. Based on the findings, 40% water and 8% sugar level were optimized for the preparation of the beverage. Apparent viscosity and acidity increased whilst pH and probiotic counts declined during storage, irrespective of packaging materials. The prepared beverage remained most acceptable at refrigeration temperature up to a period of 15 and 12 d when packaged in glass and high impact polystyrene, respectively. Furthermore, it retained a minimum recommended level of probiotic (7 log cfu/ml) during storage for 15 d at 4 °C.

Development and validation of an analytical method for determination of bronopol and kathon preservative in milk.

The bronopol and kathon are chemical preservative which prevent degradation of milk samples and maintain authenticity in analysis. The detection is based on HPLC-UV-Vis spectroscopy, in which C18 column (250 mm × 4.6 mm, 5 µm) was used for chromatographic separations, with a mobile phase comprising 0.1% phosphoric acid in water: Methanol: 0.1% phosphoric acid in acetonitrile (80:10:10) at a flow rate 0.8 ml/min at ambient temperature and with the UV detection at 250 nm for bronopol and 274 nm for kathon. The retention time of bronopol, kathon (MI 2-methyl-4-isothiazolin-3-one) and kathon (CMI 5-chloro-2-methyl-4-isothiazolin-3-one) was 4.52 min, 3.98 min and 6.68 min respectively with a total run time of 10 min. The linearity of the method was satisfactory with regression coefficient (R2) = 0.99. The limit of quantification was 72, 240, 390 mg L-1 for bronopol, kathon (MI) and kathon (CMI) respectively. Five spiked levels (62.5, 125, 250, 500 and 1000 mg L-1) were used to determine the recovery of bronopol, kathon (MI) and kathon (CMI) which was found to be 95.41 ± 11.84, 95.75 ± 8.21 and 92.22 ± 14.64% respectively, with relative standard deviations in the range 5.9-14.6%. The standardized analytical method was successfully used to rapidly detect bronopol and kathon in milk samples.