Survival of <i>Lactobacillus acidophilus </i>in Fruit-Flavored Greek Yogurt Acid Whey

Greek yogurt has become much more popular within the last 15 to 20 years. The by-product of Greek yogurt manufacture is acid whey. Although acid whey has been considered a waste product, researchers are exploring various uses of this whey. Since the health benefits of consuming probiotics are widely known, one may propose adding probiotics to acid whey to form a probiotic beverage. Typically, probiotic bacteria do not thrive in acidic conditions. It would be beneficial to determine if the probiotic Lactobacillus acidophilus can survive in these acidic conditions. The objectives were to determine the growth of L. acidophilus in acid whey resulting from manufacturing Greek yogurt and to study any changes in apparent viscosity, pH, and titratable acidity over 4 weeks of refrigerated storage. Plain yogurt was manufactured, and whey was separated from plain yogurt to yield Greek yogurt and acid whey. Acid whey was batch pasteurized, cooled, sweetened, flavored with pineapple flavoring, inoculated with L. acidophilus, and stored at 4°C for 4 weeks. The log L. acidophilus counts progressively decreased from 7.84 immediately after manufacture to 2.06 at week 4. There were no significant changes in pH and titratable acidity of the pineapple-flavored probiotic acid whey over 4 weeks of storage, indicating product stability over shelf life. Viscosity changed over the storage time with minimum values at week 2 and maximum values at week 4. Although the counts declined over 4 weeks of storage, some L. acidophilus survived in the pineapple-flavored acid whey.

Parameterization of below-cloud scavenging for polydisperse fine mode aerosols as a function of rain intensity

The below-cloud aerosol scavenging process by precipitation is one of the most important mechanisms to remove aerosols from the atmosphere.Due to its complexity and dependence on both aerosol and raindrop sizes,wet scavenging process has been poorly treated,especially during the removal of fine particles.This makes the numerical simulation of below-cloud scavenging in large-scale aerosolmodels unrealistic.To consider the slip effects of submicron particles,a simplified expression for the diffusion scavenging was developed by approximating the Cunningham slip correction factor.The derived analytic solution was parameterized as a simple power function of rain intensity under the assumption of the lognormal size distribution of particles.The resultant approximated expression was compared to the observed data and the results of previous studies including a 3D atmospheric chemical transport model simulation.Compared with the default GEOS-Chem coefficient of 0.00106R0.61 and the observation-based coefficient of 0.0144R0.9268,the coefficient of a and b in∧m=aRb spread in the range of 0.0002-0.1959 for a and 0.3261-0.525 for b over a size distribution of GSD of 1.3–2.5 and a geometric mean diameter of 0.01-2.5μm.Overall,this study showed that the scavenging coefficient varies widely by orders of magnitude according to the size distribution of particles and rain intensity.This study also demonstrated that the obtained simplified expression could consider the theoretical approach of aerosol polydispersity.Our proposed analytic approach showed that results can be effectively applied for reduced computational burden in atmospheric modeling.