Biomaterial Database

Isolation, characterization, and influence of native, nonstarter lactic acid bacteria on Cheddar cheese quality. 2001

P A Swearingen, and D J O'Sullivan, and J J Warthesen

Minnesota-South Dakota Dairy Foods Research Center, Department of Food Science and Nutrition, University of Minnesota, St. Paul 55108, USA.

To determine whether adventitious nonstarter lactic acid bacteria (NSLAB) might affect cheese flavor and quality, we studied a population of NSLAB present in 30 premium quality Cheddar cheeses (3-mo ripened) produced at a commercial facility in the United States. DNA fingerprinting analysis with a sensitive strategy for arbitrary priming polymerase chain reaction showed that 75 isolates corresponded to at least 18 distinct nonstarter organisms. According to ribotype database comparisons of representatives from the 18 groups, 9 matched Lactobacillus (closest to paracasei species), 8 matched Streptococcus thermophilus, and 1 matched to a Lactococcus species. This finding indicated that among the 75 NSLAB isolates, Lactobacillus made up 64%, S. thermophilus 32%, and Lactococcus 4%. Isolates representing 11 NSLAB groups were characterized for protease, peptidase, and diacetyl production. Based on this phenotypic analysis, two Lactobacillus isolates were evaluated as adjuncts in Cheddar cheese. All of the NSLAB identified from the adjunct cheese at 3 mo by DNA fingerprinting consisted of the adjunct lactobacilli, showing that the adjunct strains predominated throughout the early stages of ripening. The impact of adjunct lactobacilli was evident after 6 mo when free amino acids significantly increased and sensory scores improved in adjunct cheese as compared with a control cheese. The largest impact was found in adjunct cheese containing a blend of both lactobacilli strains. These results show that certain adventitious NSLAB positively contribute to flavor development.

UI	MeSH Term	Description	Entries
D007778	Lactobacillus	A genus of gram-positive, microaerophilic, rod-shaped bacteria occurring widely in nature. Its species are also part of the many normal flora of the mouth, intestinal tract, and vagina of many mammals, including humans. Lactobacillus species are homofermentative and ferment a broad spectrum of carbohydrates often host-adapted but do not ferment PENTOSES. Most members were previously assigned to the Lactobacillus delbrueckii group. Pathogenicity from this genus is rare.
D011786	Quality Control	A system for verifying and maintaining a desired level of quality in a product or process by careful planning, use of proper equipment, continued inspection, and corrective action as required. (Random House Unabridged Dictionary, 2d ed)	Control, Quality,Controls, Quality,Quality Controls
D002611	Cheese	A nutritious food consisting primarily of the curd or the semisolid substance formed when milk coagulates.	Cheeses
D004269	DNA, Bacterial	Deoxyribonucleic acid that makes up the genetic material of bacteria.	Bacterial DNA
D005511	Food Handling	Any aspect of the operations in the preparation, processing, transport, storage, packaging, wrapping, exposure for sale, service, or delivery of food.	Food Processing,Handling, Food,Processing, Food
D000596	Amino Acids	Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.	Amino Acid,Acid, Amino,Acids, Amino
D013291	Streptococcus	A genus of gram-positive, coccoid bacteria whose organisms occur in pairs or chains. No endospores are produced. Many species exist as commensals or parasites on man or animals with some being highly pathogenic. A few species are saprophytes and occur in the natural environment.
D013649	Taste	The ability to detect chemicals through gustatory receptors in the mouth, including those on the TONGUE; the PALATE; the PHARYNX; and the EPIGLOTTIS.	Gustation,Taste Sense,Gustations,Sense, Taste,Senses, Taste,Taste Senses,Tastes
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor
D016133	Polymerase Chain Reaction	In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.	Anchored PCR,Inverse PCR,Nested PCR,PCR,Anchored Polymerase Chain Reaction,Inverse Polymerase Chain Reaction,Nested Polymerase Chain Reaction,PCR, Anchored,PCR, Inverse,PCR, Nested,Polymerase Chain Reactions,Reaction, Polymerase Chain,Reactions, Polymerase Chain