"Impact of Concentrated whey on dairy products"

Abstract

Whey retains 50% of milk solids and can be transformed into various products like whey protein concentrate, whey proteins isolate, powder and whey cheese. The production of whey cheese (Ricotta) is the cheapest way to conserve whey by the small scale cheese producers in Pakistan. The impact of temperature (60-90°C), pH (3-7) and CaCl2 concentration (2.0-6.0mM) on the Ricotta cheese yield from liquid and concentrated whey was investigated in the study. Twenty preliminary experiments were run following Central Composite Design (CCD) on liquid and concentrated whey separately. Response Surface Methodology (RSM) was used to optimize the conditions and obtained an empirical polynomial model to fit the experimental data. The conditions optimized by the RSM showed lower yield than the observed values developed by CCD. Three best conditions for higher observed yield values were selected for the production of Ricotta cheese from liquid (RCLW1: 75°C, pH 8.4, CaCl2 4mM, RCLW2: 100°C, pH 5, CaCl2 4mM, RCLW3: 90°C, pH 7, CaCl2 6mM) and concentrated whey (RCCW1: 75°C, pH 8.4, CaCl2 4 mM, RCCW2: 100°C, pH 5, CaCl2 4mM, RCCW3: 90°C, pH 7, CaCl2 6mM) with the addition of buffalo skim milk (9:1 ratio). The RCCW2 and RCLW3 exhibited the highest yield, proteins and total solids. The fat and ash contents were higher in RCCW as compared to RCLW. The lactose and total solids varied from 5.42 to 5.82% and 29 to 34% respectively among cheese samples. Total viable counts (TVC) of Ricotta cheese were in the range from 4.16×104 to 7.19×104 cfu g-1. Comparatively higher numerical values of TVC were observed in RCLW than RCCW. Yeast and molds varied from 1.20×102 to 3.51×102 cfu g-1 and RCCW1 had the highest count. Higher scores were awarded to RCLW3 followed by RCLW2 with respect of sensory evaluation. The cheeses prepared from concentrated whey (CW) obtained poor scores due to its dark color and bitter taste. The CW was also used for yogurt (5-30%) preparation. The increase in total solids (13 to 23%) with the addition of CW had a positive impact up to 10%, but the higher levels produced some quality defects in yogurts like syneresis, low WHC and viscosity. It is concluded from research that Ricotta cheese prepared from liquid and concentrated whey at 90°C, pH 7, CaCl2 6mM has higher yield, but RCCW can be used as an ingredient in other food products due to its higher fat content and protein content but not for direct consumption due to its lower sensory quality as compared to RCLW. It is also concluded that addition of 10% concentrated whey to yogurt improves the sensory, rheological and compositional attributes of set yogurt.