Commercial cheese is manufactured by bacterial fermentation of pasteurized milk. Selected bacteria, referred to as starter cultures, are added to the milk to implement the fermentation. However, some Wild bacteria, nonstarter bacteria, may also be present in cheese, which may alter the desired quality of the cheese. Thus, cheese manufactured under seemingly identical conditions in two cheese-making facilities may produce cheese of differing quality due to the present of different indigenous nonstarter bacteria. To test the impact of two nonstarter bacteria, R50 and R21, on cheese quality, the nonstarter bacteria were added to the cheese to see if it impacted the quality of the cheese. The researchers decided to use four types of nonstarter bacteria: a control ( no nonstarter bacteria added), addition of R50, addition of R21, and addition of a blend of R50 and R21. Twelve containers of cheeses were made, 3 of each of the four types of nonstarter bacteria, with the type of bacteria randomly assigned to the cheese containers. Each of the 12 containers of cheese was then divided into four portions. The four portions were then randomly assigned to one of four aging times: 1 day, 28 days, 56 days, and 84 days. At the end of the specified aging period, the cheese was measured for total free amino acids. The researchers were particularly interested in the bacterial effects and their interaction with aging times.