Lactobacilli in Cheddar cheese

Abstract

With 1 Figure) Before the development of selective media for lactobacilli, it was almost impossible to determine the numbers of these organisms during the early stages of cheese ripening, when the starter streptococci were dominant. Early workers (i, 2) consequently assumed that the lactobacilli did not reach significant numbers until the streptococci had declined appreciably in numbers. This view is still expressed in recent text-books (3,4). Recent British work (5) however, using a medium which inhibited growth of the starter streptococci, indicates that the lactobacilli grow slowly but steadily from the beginning of the ripening period. This has recently been confirmed by Naylor & Sharped), who made intensive studies of one experimental cheese over a 6-month period.Since 1954 the Dairy Technology Research Unit has been studying the enhancement of flavour in Cheddar cheese made from pasteurized milk. In each series of experiments, representative cheeses have been examined at intervals for the numbers of various groups of bacteria-lactobacilli, enterococci, coliforms, lipolytic and proteolytic-as well as the total viable count. Thus we have accumulated a considerable volume of data. In view of the recent report (7) of erratic fluctuations in counts of lactobacilli it was considered timely to report our quite different findings. MATERIALS AND METHODSIn our experimental cheese-making, samples were taken (a) of the milk in the vat before adding the starter but after other special inocula had been added, and (6) of the cheese after approximately 2-5 days, 2 weeks, 3, 6 and 12 months. The cheeses were customarily ripened at 58° F. for 2 weeks, then at 40° F. for 1 year or longer. Cheese samples of about 10 g. were taken from the 10 lb. cheese with a trier, discarding the surface portion. After grinding with a pestle and mortar, 5 g. were weighed out and added to 95 ml. of 2 % sodium citrate solution tempered at 45° C. After shaking to dissolve and suspend the cheese, further dilutions were made using buffered distilled water (8) and plates poured from appropriate dilutions with Rogosa's(9) medium. Counts were made after 5 days' incubation at 32° C.

Spatial and temporal distribution of non-starter lactic acid bacteria in Cheddar cheese

“…1994). Concurrently a dramatic increase in the adventitious NSLAB population from ~log 3 to between log 6 and 7 cfu g –1 occurs (Naylor and Sharpe 1958a; Johns and Cole 1959).…”

Phenotypic and Genotypic Characterization of Non-Starter Lactic Acid Bacteria in Mature Cheddar Cheese

“…During the ripening of Cheddar cheese, the starter organisms autolyze, releasing growth substrates and enzymes; concomitantly, an increase in NSLAB levels occurs to ϳ10 7 CFU ⅐ g Ϫ1 of cheese 6 to 8 weeks postmanufacture (22,34). The NSLAB community is predominated by mesophilic (group II) lactobacilli, though pediococci and micrococci may also be found (1,8,16).…”

Effect of temperature during early stage of curing upon cheddar cheese characteristics

“…During a flavor study of 38 Cheddar cheeses, Johns and Cole (49) determined the number of lactobacilli in milk and cheese at various stages of ripening. Lactobacilli were found to multiply rapidly during the first few days of curing and a maximum level was attained at 3-6 months which declined appreciably at 1 year.…”