Biochemical pathways for the production of flavour compounds in cheeses during ripening: A review

In the paper

“Although LAB (Lactococcus, Lactobacillus, Streptococcus) are weakly proteolytic, they possess a very comprehensive proteinase/peptidase system that has been studied extensively and reviewed (e.g., [49,72,73]).”

What the sources say

• Partly supported

  In the ‘Streptococcus lactis var.’ section (page not provided), the paper describes limited casein hydrolysis by Streptococcus starter bacteria and peptidases in some strains. It does not establish a comprehensive proteinase/peptidase system across all three named genera or say that system has been extensively reviewed. It also describes extensive proteolysis by lactobacilli and highly proteolytic Streptococcus strains, qualifying the blanket description of LAB as weakly proteolytic. (LLM, conf=0.83)

  cites [49] 49. Dunn H.C., Lindsay R.C., Evaluation of the role of microbial Strecker-derived aroma compounds in unclean-type flavours of Cheddar cheese, J. Dairy Sci. 68 (1985) 2859-2874. sourceExperimental — accuracy not yet measured
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [72] 72. Kungi E.R.S., Micrav I., Hagting A., Poolman B., Konings W.N., The proteolytic system of lactic acid bacteria, Antonie Leeuwenhoek Int. J. Gen. M. 70 (1996) 187-221.
• ?Not checked — no full text of the sourcecites [73] 73. Law J., Haandrikman A., Proteolytic enzymes of lactic acid bacteria, Int. Dairy J. 7 (1997) 1-11. source

In the paper

“and it has been suggested [49] that perhaps the enzymatic or chemical modification of amino acids is the critical factor.”

What the sources say

• Partly supported

  The Results and Discussion (page unavailable) links amino-acid-derived compounds and peptidase activity to flavor development during Cheddar ripening. It does not suggest that enzymatic or chemical modification of amino acids is the critical factor in cheese ripening overall. (LLM, conf=0.78)

  cites [49] 49. Dunn H.C., Lindsay R.C., Evaluation of the role of microbial Strecker-derived aroma compounds in unclean-type flavours of Cheddar cheese, J. Dairy Sci. 68 (1985) 2859-2874. sourceExperimental — accuracy not yet measured

In the paper

“LAB possess a cell envelope-associated proteinase (PrtP), several intracellular oligoendopeptidases (PepO) and (PepF), at least 3 general aminopeptidases (PepN, PepC, PepG), a glutamyl aminopeptidase (PepA), a pyrolidone carboxylyl peptidase (PCP), a leucyl aminopeptidase (PepL), a prolyl-dipeptidyl aminopeptidase (PepX), a proline iminopeptidase (PepI), aminopeptidase P (PepP), prolinase (PepR),”

What the sources say

• Partly supported

  In the “Streptococcus lactis var.” section (page unavailable), the paper says some strains of Streptococcus cremoris possess peptidases and discusses proteolysis by lactobacilli and starter bacteria. It does not identify PrtP or any of the other named enzymes, or establish that LAB generally possess the listed set. (LLM, conf=0.82)

  cites [49] 49. Dunn H.C., Lindsay R.C., Evaluation of the role of microbial Strecker-derived aroma compounds in unclean-type flavours of Cheddar cheese, J. Dairy Sci. 68 (1985) 2859-2874. sourceExperimental — accuracy not yet measured
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [72] 72. Kungi E.R.S., Micrav I., Hagting A., Poolman B., Konings W.N., The proteolytic system of lactic acid bacteria, Antonie Leeuwenhoek Int. J. Gen. M. 70 (1996) 187-221.
• ?Not checked — no full text of the sourcecites [73] 73. Law J., Haandrikman A., Proteolytic enzymes of lactic acid bacteria, Int. Dairy J. 7 (1997) 1-11. source

In the paper

“Both species produce aspartyl proteinases and metalloproteinases; P. camemberti also possesses an intracellular acid proteinase, whereas P. roqueforti produces a broad specificity carboxypeptidase, an extracellular metallo-aminopeptidase (see [57]) and amino-and carboxypeptidases [110].”

What the sources say

• ?Not checked — no full text of the sourcecites [57] 57. Foissy H., Examination of Brevibacterium linens by an electrophoretic zymogram technique, J. Gen. Microbiol. 80 (1974) 197-207. source
• ?Could not verify

  Split into 2 atoms — 0 confirmed, 0 partially supported, 0 disputed, 0 misattributed, 2 unverifiable. Expand the claim to see per-atom verdicts.

  cites [110] 110. Molimard P., Spinnler H.E., Review: com- pounds involved in the flavour of surface mold- ripened cheeses: origins and properties, J. Dairy Sci. 79 (1996) 169-184. sourceExperimental — accuracy not yet measured

In the paper

“Nonstarter lactobacilli in Gouda and Vacherin du Haut-Doubs (also known as Mont d'Or) cheeses are thought to be responsible for producing p-cresol [32], whereas phenol has been found in high concentrations in Limburger cheese [111].”

What the sources say

• Partly supported

  The Discussion (page unavailable) reports cresol in one Vacherin–Mont d’Or sample and relates it to reports of cresol in some Gouda cheeses. It does not identify the compound as p-cresol or attribute its production to nonstarter lactobacilli; instead, it discusses a hypothesis of bacterial contamination of rennet and says the origin in its Vacherin sample is uncertain. The Limburger clause has a separate citation and is not assessed here. (LLM, conf=0.88)

  cites [32] 32. Dumont J.P., Roger S., Cerf P., Adda J., Étude de composés volatils neutres présents dans le Vacherin, Lait 54 (1974) 501-516. sourceExperimental — accuracy not yet measured
• ?Not checked — no full text of the sourcecites [111] 111. Molimard P., Le-Quere J.L., Spinnler H.E., Les lipides et la flaveur des produits laitiers, Oléagin. Corps Gras Lipides 4 (1997) 301-311.

In the paper

“Ammonia is an important constituent in many cheeses such as Camembert, Gruyère and Comté [53], and P. camemberti, G. candidum and Br.linens play a major role in ammonia production [67].”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [53] 53. Eriksen S., Flavour of milk and milk products. 1. The role of lactones, Milchwissenschaft 31 (1975) 549-552.
• Supported

  The citation [67] is attached to the claim about ammonia-producing microorganisms, not the preceding claim about Camembert, Gruyère and Comté. In “Lactate Metabolism and Ammonia Production by Pure Cultures of Ripening Microorganisms” (page unavailable), the paper reports rapid ammonia production by P. caseicolum and says G. candidum and B. linens make significant contributions during traditional mold surface-ripening, with B. linens contributing when present and supplied with amino acids. The paper uses P. caseicolum rather than the citing sentence’s P. camemberti. (LLM, conf=0.86)

  cites [67] 67. Karahadian C., Lindsay R.C., Integrated roles of lactate, ammonia, and calcium in texture development of mold surface-ripening cheese, J. Dairy Sci. 70 (1987) 909-918. source

In the paper

“The solubility of Ca-D-lactate is less that that of Ca-L-lactate, and Ca-D-lactate may crystallize in cheese forming white specks, particularly on cut surfaces (see [51]).”

What the sources say

• ?Not checked — no full text of the sourcecites [51] 51. Elsden S.R., Hilton M.G., Waller J.M., The end products of the metabolism of aromatic amino acids by Clostridia, Arch. Microbiol. 107 (1976) 283-288. source

In the paper

“Freshly-made curds of various cheese varieties have bland, and largely similar, flavours and it is during the ripening period that flavour compounds are produced which are characteristic of each variety.”

In the paper

“Certain starter bacteria (e.g., Streptococcus thermophilus) are unable to metabolize the galactose moiety of lactose and must grow with galactose-positive (Gal + ) microorganisms (e.g., Gal + lactobacilli), or galactose will accumulate in the curd.”

In the paper

“Acetate, an important flavour compound in many cheeses, in addition to being formed from lactose by lactic acid bacteria (LAB) may also be formed as a result of citrate and lactate metabolism (see below), or as a product of the catabolism”

In the paper

“Propionibacterium sp. in Swiss-type cheeses grow once the cheeses are transferred into the warm-room after brining and preferentially metabolize L-lactate to propionate, acetate and CO 2 (see Scheme 2).”

In the paper

“The yeasts and moulds rapidly metabolize lactate to CO 2 and H 2 O, and the pH of the cheese surface increases.”

In the paper

“The major biochemical pathways which occur in cheese ripening are the following: the metabolism of residual lactose, lactate and citrate (sometimes, although erroneously, referred to as 'glycolysis'), liberation of free fatty acids, FFA (lipolysis), associated catabolic reactions and the degradation of the casein matrix to a range of peptides and free amino acids, FAA (proteolysis), and subsequent”

In the paper

“Lactate contributes to the flavour of acid-curd cheeses and probably also contributes to the flavour of ripened cheese varieties, particu-larly early in maturation.”

In the paper

“The mesophilic starter bacteria produce lactic acid in the curd (ca.1%), which is quickly metabolized by secondary microorganisms (initially Geotrichum candidum and Debaryomyces hansenii, followed later by Penicillium camemberti and perhaps coryneform bacteria like Brevibacterium linens).”

In the paper

“Racemization of lactate has little impact on flavour but may have undesirable nutritional consequences, particularly for infants.”

In the paper

“The production of D-lactate during ripening is probably greater in cheeses made from raw milk but, as far as we are aware, only few studies have investigated this [130,131].”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [130] 130. Steffen C., Konzentration und Konfiguration des milchsäre im reifenden Emmentalerkäse, Diss. 4630, Eidy Tech. Hochschule, Zurich, 1971.
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [131] 131. Steffen C., Glättli H., Steiger G., Flückiger E., Bühlmann C., Lavanchy P., Nick B., Vergle- ichende Untersuchungen von Greyerzerkäsen mit und ohne Nachgärung. I Bakteriologische, biochemische, chemische und rheologische Untersuchungen, Schweiz. Milchwirtsch. Forsch. 9 (1980) 19-27.

In the paper

“The metabolism of lactose to lactate is essential to the production of all cheese varieties.”

In the paper

“Citrate metabolism by citrate-positive lactococci or Leuconostoc spp. is important in certain varieties (e.g., Dutch cheeses).”

In the paper

“The carbon dioxide produced is essential for eye development; and propionate and, to a lesser extent, acetate contribute to the flavour of these cheeses.”

In the paper

“The principal products of lactose metabolism are L-or D-lactate or a racemic mixture of both, although some strains, e.g., Leuconostoc spp., produce other products, e.g., ethanol [140].”

What the sources say

• ?Not checked — no full text of the sourcecites [140] 140. Vedamuthu E.R., The dairy Leuconostoc: use in dairy products, J. Dairy Sci. 77 (1994) 2725-2737. source

In the paper

“Hundreds of compounds have been implicated in cheese flavour; some of which have been identified in Cheddar cheese and are listed in Table I.”

What the sources say

• ?Not checked — no full text of the sourcecites [138] 138. Urbach G., Relations between cheese flavour and chemical composition, Int. Dairy J. 3 (1993) 389-422. source

In the paper

“Concentrations of amino acids generally increase during ripening, with the exception of Arg, the concentration of which is reported to decrease later in ripening [114].”

What the sources say

• ?Not checked — no full text of the sourcecites [114] 114. Nelson J.H., Jensen R.G., Pitas R.E., Pregastric esterase and other oral lipases -a review, J. Dairy Sci. 60 (1977) 327-362. source

In the paper

“Acetoin is produced from α-acetolactate by the action of acetolactate decarboxylase.”

In the paper

“Diacetyl is usually produced only in small amounts (1-10 µg•mL -1 in milk), but acetoin is generally produced in much higher quantities (10-50fold higher than diacetyl concentrations).”

In the paper

“Milk contains ca. 8 mmol .L -1 citrate, most of which is lost in the whey during cheesemaking, since ca.94% of the citrate is in the soluble phase of the milk.”

In the paper

“Deacidification of the cheese surface has a major impact on the growth of coryneform bacteria (Br.linens does not grow below pH 5.8), plasmin activity (which is optimum at alkaline pH) and has a major effect on cheese texture since Ca 2+ precipitates at the surface as Ca 3 (PO 4 ) 2 , causing a Ca 2+ gradient to develop within the cheese.”

In the paper

“The action of coagulant has been implicated in the formation of bitter peptides in cheese, and thus factors that affect the retention and activity of rennet in the curd may influence the development of bitterness.”

In the paper

“Medium and small peptides and FAA contribute to the background flavour of most cheese varieties [139] and some individual peptides have 'brothy', 'bitter', 'nutty' and 'sweet' tastes.”

What the sources say

• ?Not checked — no full text of the sourcecites [139] 139. Urbach G., Contribution of lactic acid bacteria to flavour compound formation in dairy prod- ucts, Int. Dairy J. 5 (1995) 877-903. source

In the paper

“Cit + microorganisms do not utilize citrate as an energy source, but rather it is cometabolized with lactose or some other sugar.”

In the paper

“Nevertheless, the low concentration of citrate in cheese curd (10 mmol .kg -1 ) is of great importance since it may be metabolized to a number of volatile flavour compounds by certain mesophilic starters (citrate-positive, Cit + , lactococci and Leuconostoc sp.) by pathways summarized in Figure 5.”

In the paper

“Elastase degrades α s1 -and β-caseins within 6 h of incubation, producing a wide range of peptides detectable by urea-polyacrylamide gel electrophoresis (PAGE), and has a broad specificity on β-casein [27];”

What the sources say

• ?Not checked — no full text of the sourcecites [27] 27. Considine T., Healy A., Kelly A.L., McSweeney P.L.H., Proteolytic specificity of elastase on bovine β-casein, Food Chem. 66 (1999) 463-470. source

In the paper

“Deacidification is essential for the growth of coryneform bacteria, which dominate the smear during ripening and are responsible for the characteristic flavour of these cheeses [93,120].”

What the sources say

• ?Not checked — no full text of the sourcecites [93] 93. McSweeney P.L.H., Nursten H.E., Urbach G., Flavours and off-flavours in milk and dairy prod- ucts, in: Fox P.F. (Ed.), Advanced Dairy Chem- istry, Chapman and Hall, London, UK, 2nd ed., vol. 3, 1997, pp. 403-468. source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [120] 120. Ney K.H., Wirotama I.P.G., Investigation of the aroma constituents of Fontina -an Italian cheese, Fette Seifen Anstrichm. 80 (1978) 249-251.

In the paper

“Certain sequences in the caseins are particularly hydrophobic and, when excised by proteinases, can lead to bitterness.”

In the paper

“Amines, including biogenic amines, are produced in cheese by enzymatic decarboxylation of FAA [65]; the relative concentration of each amine depends on the cheese variety and the non-starter microflora.”

What the sources say

• ?Not checked — no full text of the sourcecites [65] 65. Joosten H.M.L.J., Stadhouders J., Conditions allowing the formation of biogenic amines in cheese. 1: Decarboxylase properties of starter bacteria, Neth. Milk Dairy J. 41 (1987) 247-258. source

In the paper

“Br. linens secretes an extracellular proteinase and an aminopeptidese and possesses a number of intracellular peptidases, which may be released on cell lysis [117].”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [117] 117. Ney K.H., Wirotama I.P.G., Unsubstituted aliphatic monocarboxilic acids, alpha-keto-acids, and amines in Cheddar cheese aroma, Z. Lebensm. Unters. Forsch. 146 (1971) 337-343.

In the paper

“Acetate is produced from citrate in equimolar concentrations.”

In the paper

“The gene encoding the citrate transport mechanism is plasmid-encoded.”

In the paper

“Blueveined cheeses are characterized by the growth of P. roqueforti throughout the cheese, and Camembert and Brie by the growth of P. camemberti on the surface.”

In the paper

“Bitterness in cheese is due mainly to hydrophobic peptides and is generally regarded as a defect, although bitter notes may contribute to the desirable flavour of mature cheese.”

In the paper

“Catabolism of FAA probably plays some role in flavour development in all varieties, but it is particularly significant in mould and smear-ripened cheeses [53].”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [53] 53. Eriksen S., Flavour of milk and milk products. 1. The role of lactones, Milchwissenschaft 31 (1975) 549-552.

In the paper

“Citrate is not metabolized by S. thermophilus nor by thermophilic lactobacilli, but is metabolized by certain mesophilic lactobacilli in the NSLAB flora.”

In the paper

“Diacetyl could be produced directly from acetaldehyde-thiamine pyrophosphate (TPP) and acetyl-CoA by enzymic action, but diacetyl synthase has never been identified clearly in LAB.”

In the paper

“Alternatively, α-acetolactate, formed from the reaction of pyruvate and acetaldehyde-TPP, is very unstable and could be decarboxylated non-oxidatively to form acetoin, or oxidatively to form diacetyl.”

In the paper

“Fox and Wallace [50] have suggested that flavour and the concentration of FAA could not be correlated, since different cheeses (e.g., Cheddar, Gouda and Edam) have very different flavours, although the concentration and relative proportions of FAA are generally similar.”

What the sources say

• ?Not checked — no full text of the sourcecites [50] 50. Eigel W.N., Butler J.E., Ernstrom C.A., Farrell H.M. Jr., Harwalkar V.R., Jenness R., Whitney R.McL., Nomenclature of proteins of cow's milk: fifth revision, J. Dairy Sci. 67 (1984) 1599-1631. source

In the paper

“Pure cultures of Leuconostoc sp.do not produce acetoin or diacetyl because pyruvate is an intermediate of both lactose and citrate metabolism and the pyruvate produced from citrate metabolism is converted to lactate and acetylphosphate (via acetyl-CoA).”

In the paper

“The principal amines in most cheeses are tyramine and histamine (see Scheme 6) produced by decarboxylation of Tyr and His, respectively [53,124]”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [53] 53. Eriksen S., Flavour of milk and milk products. 1. The role of lactones, Milchwissenschaft 31 (1975) 549-552.
• Not checked yet

  Checked before — its earlier verdict is held back until a new check runs.

  cites [124] 124. Olson N.F., The impact of lactic acid bacteria on cheese flavor, FEMS Microbiol. Rev. 87 (1990) 131-147. source

In the paper

“The principal amino acids in Cheddar cheese are Glu, Leu, Arg, Lys, Phe and Ser [147].”

What the sources say

• ?Not checked — no full text of the sourcecites [147] 147. Wijesundera C., Drury L., Muthuku-marappan K., Gunasekaran S., Everett D.W., Flavour developmenet and distribution of fat globule size and shape in Cheddar-type cheeses made from skim milk homogenised with AMF or its fractions, Aust. J. Dairy Technol. 53 (1998) 107.

In the paper

“In mixed cultures, Leuconostoc sp.produce diacetyl and acetoin, perhaps because their ability to take up lactose is greatly reduced below pH 5.5.”

In the paper

“it is therefore possible that indigenous elastase in milk may be of significance to proteolysis in cheese, especially cheese produced from raw milk.”

In the paper

“Products of citrate metabolism produced by pure cultures of Cit + lactococci and Leuconostoc sp.differ: the former produce diacetyl, acetoin and CO 2 in addition to lactate, but the latter produce large amounts of lactate and acetate.”

In the paper

“Citrate metabolism is of particular importance in Dutch-type cheeses where the CO 2 produced is responsible for eye formation.”

In the paper

“Decarboxylation involves the conversion of an amino acid to the corresponding amine with the loss of carbon dioxide.”

In the paper

“The final products of proteolysis are FAA, the concentrations of which depend on the cheese variety, and which have been used as indices of ripening [6,89,114].”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [6] 6. Aston J.W., Douglas K., The production of volatile sulphur compounds in Cheddar cheeses during accelerated ripening, Aust. J. Dairy Tech- nol. 38 (1983) 66-70.
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [89] 89. McSweeney P.L.H., Fox P. F., Indices of Ched- dar cheese ripening, Proc. 5th Cheese Symp., Moorepark, Fermoy, Co. Cork, Ireland, 1997, pp. 73-89.
• ?Not checked — no full text of the sourcecites [114] 114. Nelson J.H., Jensen R.G., Pitas R.E., Pregastric esterase and other oral lipases -a review, J. Dairy Sci. 60 (1977) 327-362. source

In the paper

“relative proportions of individual amino acids are thought to be important for the development of the characteristic flavour [19].”

What the sources say

• ?Not checked — no full text of the sourcecites [19] 19. Broome M.C., Krause D.A., Hickey M.W., The use of non-starter lactobacilli in Cheddar cheese manufacture, Aust. J. Dairy Technol. 45 (1990) 67-73.

In the paper

“Acetate is produced from acetylphosphate with the concomitant production of 1 mol ATP, resulting in faster growth of the microorganism.”

In the paper

“Methanethiol is present in Camembert together with other sulphur compounds, such as 2,4-dithiapentane, 3,4-dithiahexane, 2,4,5-trithiahexane and 3-methylthio-2,4dithiapentane, and these compounds are responsible for the garlic note which can be found in well-ripened Camembert cheese [3].”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [3] 3. Adda J., Czulak J., Mocquot G., Vassal L., in: Cross H.R., Overby A.J. (Eds.), Cheese, Meat Science, Milk Science and Technology, Else- vier Sci. Publ., Amsterdam, The Netherlands, 1988, pp. 373-392.

In the paper

“In Cheddar (and other varieties made using only a primary starter), phenylethanol and phenylacetaldehyde can be produced by Strecker degradation of phenylalanine [34]; high concentrations of phenylacetaldehyde contribute to astringent, bitter and stinging flavour sensations.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [34] 34. Fox P.F., Lucey J.A., Cogan T.M., Glycolysis and related reactions during cheese manufac- ture and ripening, Crit. Rev. Food Sci. Nutr. 29 (1990) 237-253.

In the paper

“DMS is a product of the metabolism of propionic acid bacteria formed from Met, and is a component of Swiss cheese flavour [2].”

What the sources say

• ?Not checked — no full text of the sourcecites [2] 2. Adda J., Gripon J.C., Vassal L., The chemistry of flavour and texture generation in cheese, Food Chem. 9 (1982) 115-129. source

In the paper

“Catabolism of Tyr (Fig. 13c) results in the formation of p-hydroxy-phenylpyruvate.”

In the paper

“DMS concentrations in Cheddar cheese remain constant for up to 6 months, but decrease thereafter [6].”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [6] 6. Aston J.W., Douglas K., The production of volatile sulphur compounds in Cheddar cheeses during accelerated ripening, Aust. J. Dairy Tech- nol. 38 (1983) 66-70.

In the paper

“DMS and DMDS could be produced directly from methanethiol, but it is unclear how DMTS is produced in cheese.”

In the paper

“Fourteen amines (primary and secondary) have been found in Cheddar cheese [102], and 8 amines in German blue-mould cheese [103].”

What the sources say

• ?Not checked — no full text of the sourcecites [102] 102. Rattray F.P., Fox P.F., Healy A., Specificity of an extracellular proteinase from Brevibacterium linens ATCC 9174 on bovine β-casein, Appl. Environ. Microbiol. 63 (1997) 2468-2471. source
• ?Not checked — no full text of the sourcecites [103] 103. Reps A., Bacterial surface-ripened cheeses, in: Fox P.F. (Ed.), Cheese: Chemistry, Physics and Microbiology, 2nd ed., vol. 2, Chapman & Hall, London, 1993, pp. 137-172. source

In the paper

“In cheeses such as Cheddar, which lacks a surface microflora, flavour is produced by starter and non-starter bacteria and their enzymes, and the production of methanethiol is thought to be a chemical process [69];”

What the sources say

• ?Not checked — no full text of the sourcecites [69] 69. Kim J.C., Olson N.F., Production of methanethiol in milk-fat coated microcapsules containing Bre- vibacterium linens and methionine, J. Dairy Res. 56 (1989) 799-811. source

In the paper

“Monoamine intoxication is characterized by an increase in blood pressure, resulting in palpitations, severe headaches, hypertension, nausea and vomiting, and has been associated with the consumption of cheese [87].”

What the sources say

• ?Not checked — no full text of the sourcecites [87] 87. McCabe B.J., Dietary tyramine and other pres- sor amines in MAOI regimens: a review. Jamer. Diet. Assoc., 86 (1986) 1059-1064. source

In the paper

“Histamine when present at high levels can result in food poisoning [123], and some cases of histamine poisoning have occurred subsequent to the consumption of cheese [135].”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [123] 123. Olivecrona T., Vilaró S., Bengtsson-Olivecrona G., Indigenous enzymes in milk. II. Lipases in milk, in: Fox P.F. (Ed.), Advanced Dairy Chem- istry. 1. Proteins, Elsevier Appl. Sci., London, 1992, pp. 292-310.
• ?Not checked — no full text of the sourcecites [135] 135. Taylor S.L., Keefe T.J., Windham E.S., Howell J.F., Outbreak of histamine poisoning associ- ated with consumption of Swiss cheese, J. Food Protect. 45 (1982) 455-457. source

In the paper

“DMTS has been associated with the aroma of cooked cabbage, broccoli, or cauliflower, and has been identified in Parmesan [10] and Cheddar [152] cheeses.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [10] 10. Barbeiri G., Bolzoni L., Careri M., Mangia A. Parolari G., Spagnoli S., Virgili R., Study of the volatile fraction of Parmesan cheese, J. Agric. Food Chem. 42 (1994) 1170-1176.
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [152] 152. Wood A.F., The determination of volatile com- pounds in cheese, M. Appl. Sci. thesis, Queens- land Univ. Technol., Brisbane, Australia, 1989.

In the paper

“2,4-Dithiapentane is an important component in Camembert flavour and can be produced by the condensation of methanethiol with formaldehyde [33].”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [33] 33. Fox P.F., Wallace J.M., Formation of flavour compounds, Adv. Appl. Microbiol. 45 (1997) 17-85.

In the paper

“Simple decarboxylation can explain the formation of most amines found in cheese, but there is no readily 312 Figure 10.General pathways for the catabolism of FAA (modified from [59]). Figure 10.Principales voies cataboliques des acides aminés libres (d'après [59]).”

What the sources say

• ?Not checked — no full text of the sourcecites [2] 2. Adda J., Gripon J.C., Vassal L., The chemistry of flavour and texture generation in cheese, Food Chem. 9 (1982) 115-129. source

In the paper

“Compounds like p-cresol, phenethanol, phenylacetaldehyde and indole have been associated with these unclean flavours, which are believed to be formed via catabolism of aromatic amino acids.”

In the paper

“No relationship has been found between the concentration of FAA and the production of amines in cheese [127], probably due to differences in the rates of decarboxylation of individual amino acids or in the rate of deamination of resulting amines [112].”

What the sources say

• ?Not checked — no full text of the sourcecites [127] 127. Smith T.A., Amines in food, Food Chem. 6 (1981) 169-200. source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [112] 112. Mulder H., Taste and flavour-forming substances in cheese, Neth. Milk Dairy J. 6 (1952) 157-167.

In the paper

“Tyramine is a biogenic amine that is frequently detected in cheese [144], and is the most common cause of monoamine intoxication.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [144] 144. Voight M.N., Eitenmiller R.R., Role of histi- dine and tyrosine decarboxylases and mono- and diamine oxidases in amine building-up in cheese, J. Food Protect. 41 (1978) 182-186

In the paper

“The concentration of carbonyl sulphide increases throughout ripening and is less variable than other sulphur compounds [7], but no correlation has been found between its concentration and cheese flavour.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [7] 7. Aston J.W., Greive P.A., Durward I.G., Dulle, J.R., Proteolysis and flavour development in Cheddar cheese, Aust. J. Dairy Technol. 38 (1983) 59-65.

In the paper

“Methional, which can be produced by Strecker degradation [5], contributes positively to cheese flavour when present at low concentrations, while at high levels, a sweet corn-like offflavour is detectable [10].”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [5] 5. Aston J.W., Dulley J.R., Cheddar cheese flavour, Aust. J. Dairy Technol. 37 (1982) 59-64.
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [10] 10. Barbeiri G., Bolzoni L., Careri M., Mangia A. Parolari G., Spagnoli S., Virgili R., Study of the volatile fraction of Parmesan cheese, J. Agric. Food Chem. 42 (1994) 1170-1176.

In the paper

“Tyr serves as precursor for 3 compounds in cheese: tyramine formed by decarboxylation, and p-cresol and phenol formed by atypical Strecker degradation [36].”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [36] 36. Fox P.F., Singh T.K., McSweeney P.L H., Bio- genesis of flavour compounds in cheese, in: Malin E.L., Tunick M.H. (Eds.), Chemistry of Structure/Function Relationships in Cheese, Plenum Press, New York, pp. 59-98.

In the paper

“Br. linens is one of the principal microorganisms found on the surface of smear-ripened cheeses, is also present on the surface of mould-ripened varieties (e.g., Camembert), and can produce methanethiol enzymatically.”

In the paper

“The catabolic products of sulphur amino acids have been implicated as major contributors to the flavour of Cheddar and many other cheese varieties, but their importance in smear and surface-ripened cheeses appears to be accentuated by their high concentration in the surface smear [2,14,34,57].”

What the sources say

• ?Not checked — no full text of the sourcecites [2] 2. Adda J., Gripon J.C., Vassal L., The chemistry of flavour and texture generation in cheese, Food Chem. 9 (1982) 115-129. source
• ?Not matched

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  cites [14] 14. Bosset J.O., Liardon R., The aroma composi- tion of Swiss Gruyère. III. Relative changes in the content of alkaline and neutral components during ripening, Lebensm. Wiss. u. Technol. 18 (1985) 178-185.
• ?Not matched

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  cites [34] 34. Fox P.F., Lucey J.A., Cogan T.M., Glycolysis and related reactions during cheese manufac- ture and ripening, Crit. Rev. Food Sci. Nutr. 29 (1990) 237-253.
• ?Not checked — no full text of the sourcecites [57] 57. Foissy H., Examination of Brevibacterium linens by an electrophoretic zymogram technique, J. Gen. Microbiol. 80 (1974) 197-207. source

In the paper

“Although the exact pathway for the nonenzymatic formation of CH 3 SH has not been established, a mechanism proposed by Manning [84,85], in which a reducing agent produces H 2 S from cystine/cysteine, which then reacts with methionine to produce methanethiol, is accepted by many investigators [2,53,59].”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [84] 84. Manning D.J., Chemical production of essen- tial flavour compounds, J. Dairy Res. 46 (1979) 531-537.
• ?Not checked — no full text of the sourcecites [85] 85. Manning D.J., Cheddar cheese flavour studies. II: Relative flavour contributions of individual volatile components, J. Dairy Res. 46 (1979) 523-529. source
• ?Not checked — no full text of the sourcecites [2] 2. Adda J., Gripon J.C., Vassal L., The chemistry of flavour and texture generation in cheese, Food Chem. 9 (1982) 115-129. source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [53] 53. Eriksen S., Flavour of milk and milk products. 1. The role of lactones, Milchwissenschaft 31 (1975) 549-552.
• ?Not checked — no full text of the sourcecites [59] 59. Folkertsma B., Fox P.F., McSweeney P.L.H., Acceleration of Cheddar cheese ripening at ele- vated temperatures, Int. Dairy J. 6 (1996) 1117-1134. source

In the paper

“DMDS can be formed as an end-product of Strecker degradation, and has been identified in Parmesan [10], Cheddar [6,11], and surface-ripened cheeses [64].”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [10] 10. Barbeiri G., Bolzoni L., Careri M., Mangia A. Parolari G., Spagnoli S., Virgili R., Study of the volatile fraction of Parmesan cheese, J. Agric. Food Chem. 42 (1994) 1170-1176.
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [6] 6. Aston J.W., Douglas K., The production of volatile sulphur compounds in Cheddar cheeses during accelerated ripening, Aust. J. Dairy Tech- nol. 38 (1983) 66-70.
• ?Not checked — no full text of the sourcecites [11] 11. Barlow I., Lloyd G.T., Ramshaw E.H., Miller A.J., McCabe G.P., McCabe L., Correlations and changes in flavour and chemical parame- ters of Cheddar cheeses during maturation, Aust. J. Dairy Technol. 44 (1989) 7-18.
• ?Not checked — no full text of the sourcecites [64] 64. Fox P.F., McSweeney P.L.H., Proteolysis in cheese during ripening, Food Rev. Int. 12 (4) (1996) 457-509. source

In the paper

“In Emmental, 3-methylbutanal can be present at high levels, and it has been reported that even if it is not one of the compounds defining typical flavour or odour, it may play a role in suppressing the unpleasant, sweaty odour of butyric acid [113].”

What the sources say

• ?Not checked — no full text of the sourcecites [113] 113. Muller C.J., Kepner R.E., Webb A.D., Identi- fication of 3-(methylthio)-propanol as an aroma constituent in Cabernet Sauvignon and Ruby Cabernet wines, Am. J. Enol. Vitic. 22 (1971) 953. source

In the paper

“However, much work remains to be done in order to understand the mechanisms by which these primary products are converted to volatile flavour compounds.”

In the paper

“The reported pathways of Glu catabolism produce α-ketoglutarate by the action of an aminotransferase or dehydrogenase, or γ-aminobutyrate (GABA) by the action of a decarboxylase [24].”

What the sources say

• ?Not checked — no full text of the sourcecites [24] 24. Christensen J.E., Dudley, E.G., Pederson, J.A., Steele J.L., Peptidases and amino acid catabolism in lactic acid bacteria, Antonie Leeuwenhoek 76 (1999) 217-246. source

In the paper

“Three different Asp catabolic pathways have been reported [24]; however, the details and distribution of these pathways are still not well understood.”

What the sources say

• ?Not checked — no full text of the sourcecites [24] 24. Christensen J.E., Dudley, E.G., Pederson, J.A., Steele J.L., Peptidases and amino acid catabolism in lactic acid bacteria, Antonie Leeuwenhoek 76 (1999) 217-246. source

In the paper

“Much is now known of the enzyme systems involved in the conversion of caseins to FAA, but it is only recently that attention has been paid to the enzymes of starters involved in amino-acid catabolism.”

In the paper

“Thr catabolism converts Thr to acetaldehyde and Gly [86]; acetaldehyde is the flavour compound typical of yogurt flavour [134].”

What the sources say

• ?Not checked — no full text of the sourcecites [86] 86. Marshall J.D., Cole W.M., Threonine aldolase and alcohol dehydrogenase activities in Lacto- bacillus bulgaricus and Lactobacillus aci- dophilus and their contribution to flavour pro- duction in fermented milks, J. Dairy Res. 50 (1983) 375-379. source
• ?Not matched

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  cites [134] 134. Tamine A.Y., Deeth H.C., Yogurt, technology and biochemistry, J. Food Protect. 43 (1980) 939.

In the paper

“The general pathways for the formation of volatile and non-volatile compounds are now well characterized for most cheese varieties, and detailed knowledge is available on the production of the primary products of lipolysis (FFA), glycolysis (lactate and products of citrate metabolism) and proteolysis (FAA) in certain varieties (e.g., Gouda and Cheddar).”

In the paper

“However, to our knowledge there are no reports suggesting that GABA has a direct or indirect impact on cheese flavour.”

In the paper

“Cheeses containing 18-90 ppm 3-methylbutanal and 9-45 ppm 3-methylbutanol, also produced by the catabolism of branched-chain amino acids, were graded lower for flavour quality and were maltier than the control cheeses”

What the sources say

• ?Not checked — no full text of the sourcecites [18] 18. Braun S.D., Olson N.F., Microencapsulation of cell-free extracts to demonstrate the feasibility of heterogeneous enzyme systems and cofactor recycling for the development of flavour in cheese, J. Dairy Sci. 69 (1986) 1202-1208. source

In the paper

“GABA production is known to occur in cheese, and Zoon and Allersma [154] have reported a correlation between the production of CO 2 and GABA in cheese with an increasing number of eyes.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [154] 154. Zoon P., Allersma D., Eye and crack formation in cheese by carbon dioxide from decarboxyla- tion of glutamic acid. Neth. Milk Dairy J. 50 (1996) 309-318.