Romano cheese

Production of a Romano Cheese Flavor by Enzymic Modification of Butterfat... 

A Romano cheese-like aroma was produced from a butter-fat emulsion by treating it with a crude enzyme mixture isolated from Candida rugosa. The emulsion consisted of 20% butterfat and 1.5% Tween 80 in a buffer solution. The treated emulsion was held at 37°C for three hours and then aged at room temperature for three days to develop the cheese-like flavor. The volatile flavor components were isolated from both the enzyme modified butterfat (EMB) and a commercial sample of Romano cheese. The flavor isolates were separated into acidic and nonacidic fractions and analyzed by gas chromatography-mass spectrometry. The results showed good correlation between the acidic fractions of the two samples. The acidic fractions contained similar relative concentrations of eight short-chain fatty acids (C2 - Cj q). Methyl ketones and esters were major components in the nonacidic fraction of the EMB. 

A microbial esterase, Mucor miehei esterase, has been extensively studied for flavor development in cheese and was found to produce flavor notes resembling those of Fontina and Romano cheeses (4). 

The purpose of this study is to investigate the production of a Romano cheese-like flavor by enzyme modification of butterfat. Candida rugosa was selected for enzyme modification of butterfat since it possesses a high lipase activity. 

Romano Cheese and Butterfat. The volatile flavor compounds were isolated from the EMB sample, a commercial sample of Romano cheese and a butterfat control sample by vacuum steam distillation. Volatiles were isolated from 2.5L EMB in five batch isolations. The EMB was mixed in a Waring blender prior to each isolation. Romano cheese was obtained from a commercial source (Stella Romano cheese, Universal Foods Corp., Milwaukee, WI). Volatiles were isolated from 700 gm Romano cheese in five batch isolations. One hundred and forty grams of cheese were cut into pieces for each isolation and slurried with 360 ml 0.1% sodium phosphate buffer solution in a blender. Volatiles were also isolated from 500 ml of butterfat emulsion control sample (207. butterfat). 

The slurry samples of EMB, Romano cheese and butterfat were vacuum distilled at 50°C for 8 hours. The volatiles were condensed in a series of cold traps cooled with a dry ice-acetone slurry. The condensates collected in the traps were combined, saturated with sodium chloride and extracted with ethyl ether. 

A crude enzyme mixture was isolated from the fermentate of Candida rugosa (ATCC No. 14,830), which is reported to produce high activity lipases ( ). The enzyme mixture was added to a 20% butterfat emulsion. A cheese-like flavor developed after 3 hours of incubation at 37°C. A desirable Romano cheese note developed after continued incubation at room temperature for three days. Nelson (6) studied lipolyzed butterfat flavor and concluded that the surface active characteristics of both fatty acids and mono- and diglycerides were important in the lipolyzed system. A tempering period of hours or even days was usually required to establish equilibrium at the interface of aqueous and fat phases. He pointed out that the lipolyzed flavor appeared to intensify as the equilibration proceeded and that this intensification was sometimes mistaken for residual lipolytic activity. 

Sensory Evaluations. Summary descriptions of the aroma and flavor-by-mouth of the EMB were established by a panel of five trained flavorists. The aroma of the neat sample was described as strong cheesy, strong Romano cheese-like with slight milky, creamy, ketonic and soapy notes. The aroma of the sample in a 0.5% NaCl solution at a level of 0.6% was described as soapy and milky with slight Romano cheese-like, acid and ketonic notes. The flavor-by-mouth of the sample in the NaCl solution was described as containing slight sharp cheese, bitter and waxy notes. 

Acidic Components. The Romano cheese-like flavor of the enzyme-modified butterfat led to a study of its volatile flavor compounds. Table I lists the compounds identified, their absolute concentra-... 

The composition of the samples is very similar. Both contain eight n-fatty acids (C2 - C q). In addition, sorbic acid, a preservative, was present in the commercial product. The quantity of the acidic components isolated from the volatiles of the EMB sample was more than three times greater than that of the commercial Romano cheese. Harper (12) reported that butanoic acid and other higher fatty acids may be related to the intensity and character of Romano cheese flavor. 

Nonacidic Components. Figure 1 shows the total ion chromatograms obtained from the nonacidic fractions of the flavor isolates. A total of 22 compounds were identified in the EMB and 12 in the Romano cheese. Table II lists the volatile flavor compounds identified in the nonacidic fractions. 

A series of ethyl esters of fatty acids, from butanoate to tetradecanoate, were identified in the EMB. Two esters, ethyl oc-tanoate and ethyl nonanoate, were found in Romano cheese. Esters are important flavor compounds in cheeses however, a high concentration of esters may cause a "fruity" defect in cheese flavor, y- and 6-dodecalactone were identified in the EMB sample as well as in Romano cheese. Lactones are well distributed in food flavors. 

Benzaldehyde and phenylacetaldehyde were identified in Romano cheese. These two compounds also have been found in Cheddar, Swiss and Blue cheeses. Benzaldehyde has a powerful, sweet, almond-like odor and exists in many foods. Phenylacetaldehyde has a strong, sweet floral, penetrating aroma and is found in many cooked foods. 

Figure 1. Total Ion Chromatograms of the Nonacidic Fractions from the Enzyme Modified Butterfat (EMB) and Romano Cheese.

Comparison of the acidic volatile profiles indicates that the EMB is similar to Romano cheese. This correlates well with the flavorists impressions of the aroma and flavor-by-mouth of this sample. Nonacidic volatile flavor profiles of EMB and Romano cheese are dissimilar. This indicates different formation pathways for these two samples. Current studies are investigating applications of the EMB as a flavoring agent and the feasibility for commercial application. 

Ho s group at Rutger s describe the use of enzymes from Candida rugosa to convert butterfat to a series of neutral and acidic compounds possessing a Romano cheese flavor. Similar technology is used by the food industry to produce enzyme modified cheese from young Cheddar cheese. The final product possesses a more intense natural aroma and taste. Similar techniques could undoubtedly be used for the production of other natural cheese flavors. 

Other enzymes, such as lipase, which could come from pig (which have been used for some Romano cheeses) need to be verified. Even preservatives, such as propionate, must be reviewed before using. Any animal fatty acid derivatives must be carefully monitored, or halal certified by a mullah, before using with other halal ingredients. Animal fatty acids will always be a concern for halal due to possible pork contamination, either of ingredients or from equipment. 

Presumably, the oxidation of lactate to acetate also occurs in other hard and semihard cheeses but studies are lacking. Production of lactate in Romano cheese was monitored by Mora et al. (1984). As with other varieties, L-lactate predominated initially, reaching a maximum of —1.9% at 1 day (Deiana et al., 1984). The concentration began to decrease at 10 days and was 0.2 to 0.6% at 150 to 240 days. Some of the decrease was accounted for by racemization to D-lactate, which reached a maximum at —90 day (up to 0.6% in some cheeses) and then declined somewhat. In some cheeses, acetate reached very high levels (1.2%) at —30 days, but decreased to 0.2% at 90 days the agents responsible for the metabolism of acetate were not identified, but yeasts Debaryomyces hansenii) may have been involved. 

Deiana, P., Fatichenti, F., Farris, G. A., Mocquot, G., Lodi, R., Todesco, R., and Cecchi, L. (1984). Metabolism of lactic and acetic acids in Pecorino Romano cheese made with a combined starter of lactic acid bacteria and yeasts. Lait 64, 380-394. 

Romano cheese 16 Label, flavor, appearance Cheddar cheese 7 Label,... 

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