This paper summarizes the results of 2 studies designed to investigate the influence of several manufacturing and curing treatments on the appearance of Cheddar cheese defects. Specifically, 2 defects, calcium lactate crystal formation and the expulsion of free liquid (weeping) were monitored in Cheddar cheese. Both studies were conducted at a commercial cheese manufacturing facility that produces Cheddar in 18.14-kg (40-lb) blocks. In the first study we monitored cheese calcium, both total and soluble during manufacture and early curing. In the second study we measured cheese pH from 3 d through 8 mo, as well as some factors that are influenced by cheese pH. Early cheese pH (3 d to 7 d) patterns were used to select vats of cheese for retail packaging. Mild Cheddar packaged at 30 d postmanufacture and sharp Cheddar packaged at 8 mo postmanufacture from the same vats were monitored for the incidence and severity of the defects. Our results indicated that factors measured in early stages of manufacture and curing (less than 7 d) such as cheese pH at mill, lactic acid concentration, nonprotein nitrogen, and calcium (total and soluble) in cheese did not correlate with the appearance of either calcium lactate or expulsion of free liquid in packaged cheeses. Factors including pH, lactic acid concentrations, and soluble calcium measured during curing (greater than 7 d) of cheese were found to be statistically significant in the development of defects and appeared to be associated with use of specific starter culture groups. In the study, 5 different starter culture groups, each consisting of a 4-strain blend of Lactococcus lactis ssp. cremoris and Lactococcus lactis ssp. lactis, were used to manufacture the cheeses. Cheese manufactured with one particular culture group showed no incidence of calcium lactate crystal formation or weeping during curing and shelf-life of cheeses in this study. This starter group also generated the least amount of pH change in cheese during the first month of curing. From these results we conclude that starter culture group, more than any other factor measured, played an important role in the development of calcium lactate and liquid expulsion defects in Cheddar cheese. Starter culture group appeared to strongly influence cheese pH, lactic acid, and soluble calcium concentrations during curing and storage.

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Colorado Springs Utilities (Utilities) recently conducted an evaluation on the feasibility of using biosolids as a biofuel for power generation. It focused on the viability of transporting raw primary and secondary solids from the Las Vegas Street Wastewater Treatment Facility (LVSWWTF) to the Martin Drake Power Plant (Drake), using steam from any one of the three natural circulation coal-fired boilers to thermally dry the biosolids, and then beneficially using the dried product as a renewable energy fuel source. LVSWWTF's treatment capacity is rated at 2.8 cubic meters per second (m 3 /s) for total cold weather flow and 3.2 m 3 /s for warm weather flow [65 million gallons per day (mgd)/75mgd]. The boilers at Drake are rated at 49 megawatts (MW), 85 MW, and 140 MW.The study demonstrated that the process would be economically and technically viable. Commingling and co-firing the dried biosolids with coal in the Drake facility should have negligible impact on power generation capacity or boiler operation, with minimal risk of slagging or fouling. Odor control, dust control, condensate return, and reliability issues were also determined to be manageable. The energy potential of Utilities' dried biosolids is on the order of 18,600 kilojoule (kJ)/dry kilogram (kg) [8,000 British thermal unit (Btu)/dry pound (lb)], making it equivalent to a sub-bituminous coal. In addition to evaluating the technical and economic feasibility of this process, the team investigated the experiences of power utilities in Europe with co-firing biosolids and coal.