The accelerated ripening of cholesterol-reduced Cheddar cheese by crosslinked β-cyclodextrin

Article Outline

• Abstract
• Introduction
• Materials and Methods
  • Materials
  • Milk Treatment and Cholesterol Removal
  • Manufacture of Cheddar Cheese
• Extraction and Determination of Cholesterol
  • Analysis of Chemical Composition and Yield of Cheese
  • Analysis of Short-Chain FFA
  • Analysis of FAA
  • Rheological Analysis
  • Sensory Analysis
  • Statistical Analysis
• Results and Discussion
  • Global Composition
  • Short-Chain FFA
  • FAA
  • Rheological Characteristics
  • Sensory Characteristics
  • Ripening Study
  • Short-Chain FFA
  • FAA
  • Rheological Characteristics
  • Sensory Characteristics
• Acknowledgments
• References
• Copyright

Abstract 

This study was carried out to investigate the influence of salt content on cholesterol-reduced Cheddar cheese obtained by a treatment with crosslinked β-cyclodextrin (β-CD) and to find if the ripening process was accelerated in cholesterol-reduced cheese. The crosslinked β-CD used was made by adipic acid. A primary study indicated that the chemical and rheological properties were not changed by the salt addition and the composition of Cheddar cheese treated with crosslinked β-CD was similar to untreated Cheddar cheese. Approximately 91 to 92% cholesterol reduction was observed in the cheeses that were treated using β-CD. In a subsequent study, we found accelerated ripening by the crosslinked β-CD based on the productions of short-chain free fatty acids and free amino acids. In rheological properties, elasticity, cohesiveness, and gumminess scores in the cholesterol-reduced Cheddar cheese were significantly greater at 5 wk ripening than those in the control at 4 mo ripening. At the early stage of ripening, most flavor properties such as rancidity, bitterness, and off-flavor in the cholesterol-reduced cheese were greater. With ripening, however, those scores changed to similar or lower scores than those in the control. The present study indicated that the crosslinked β-CD treatment for cholesterol removal showed accelerated ripening effect on the properties of Cheddar cheese.

Key words: Cheddar cheese, crosslinked β-cyclodextrin, cholesterol removal, accelerated ripening

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Introduction 

The quality of cheese, as perceived by the consumer, will pass through a maximum during ripening. The characteristic properties (i.e., flavor and consistency) take a certain time to develop (Walstra et al., 1999). Storage and maintenance of cheese are expensive because of investments in buildings and machinery and costs of energy and labor. Reducing the ripening time is therefore attractive from an economic point of view. Acceleration of cheese ripening offers undoubted economic and technological advantages to producers (Fox, 1989a). The use of elevated ripening temperatures to accelerate proteolysis is one of the most practical methods to accelerate ripening (Law, 1984; Aston et al., 1985; Fox and McSweeney, 1998; O’Reilly et al., 2003). In addition, Yokoyama et al. (1992) filed a patent for acceleration of cheese ripening using high pressure, which reported that Cheddar cheese could be ripened in 3 d by treatment at 50MPa, compared with a 6-mo ripening period for conventional Cheddar cheese.

The ripening of Cheddar cheese involves a concerted series of microbiological, biochemical, and physicochemical changes that are collectively responsible for the development of its texture, flavor, and aroma (Mc-Sweeney, 2004). Accelerated cheese ripening processes are primarily aimed at accelerated flavor formation (i.e., a strong proteolysis or lipolysis), while maintaining a satisfactory texture. Most studies on the acceleration of cheese ripening were done by incorporating various proteolytic enzymes into milk or cheese curds during cheese manufacture (O’Keeffe et al., 1978; Kwak et al., 1989). During ripening, the cheese casein is hydrolyzed into peptides and free amino acids (FAA), and milk fat into FFA to have authentic cheese flavor and texture (Morris, 1978; Fox, 1989b). Texture is one of the primary quality attributes of Cheddar cheese, with its development being inextricably linked with the biochemical and physicochemical changes that occur during ripening (Lucey et al., 2003). To date, the exact mechanisms responsible for texture development of Cheddar cheese during ripening have not been fully elucidated.

In our previous study (Kwak et al., 2002), it was reported that cream treated with β-cyclodextrin (β-CD) before cheese manufacture showed accelerated ripening in Cheddar cheese. Based on those findings, the objectives of this study were to examine the influence of salt content on properties of cholesterol-reduced Cheddar cheese and whether crosslinked β-CD treatment may have an effect on ripening acceleration on Cheddar cheese or not.

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Materials and Methods 

Materials 

Raw milk was obtained from Biggrae Dairy Plants (Kyunggi-do, Korea). Commercial β-CD (purity 99.1%) was purchased from Nihon Shokuhin Cako Co. Ltd. (Osaka, Japan). Cholesterol and 5α-cholestane were purchased from Sigma Chemical Co. (St. Louis, MO), and all solvents were gas chromatography grade.

Milk Treatment and Cholesterol Removal 

Bulk raw milk was pasteurized at 72°C for 15s and cream was separated at 50°C using a cream separator (CE Elecrem, Vanves, France). Pasteurized cream (15kg) was stirred with 10% crosslinked β-CD at 1,400rpm with a blender (Tops, Misung Co., Seoul, Korea) in a temperature-controlled water bath at 40°C for 30min, and then centrifuged at 166×g for 10min to remove β-CD. All treatments were run in triplicate (Han et al., 2005). The cholesterol-removed cream was mixed with skim milk at 70.4kg/cm² (HC 5,000, Microfluidics Corp., Newton, MA).

Manufacture of Cheddar Cheese 

The cholesterol-reduced milk (15kg) was warmed to 36°C. A frozen concentrated direct vat set mesophilic lactic acid starter culture for Cheddar cheese (R-703, Chr. Hansen's Lab., Copenhagen, Denmark) was added to the milk. The cheese making process was described by Metzger and Mistry (1994). After manufacturing, to study the effect of salt addition on properties of cholesterol-reduced Cheddar cheese, 5 concentrations of salt (0, 1.0, 1.5, 2.0, 2.5, or 3.0%) were added. Then, the pressed cheeses were weighed and vacuum packaged in a barrier bag for ripening at 5°C. In a preliminary experiment, we found that the cholesterol-reduced cheese obtained by β-CD treatment ripened faster than conventional Cheddar cheese; consequently, we fixed sampling points as follows: the control cheese was manufactured from whole milk, salted 2%, and ripened for 0, 2, 4, 6, and 8 mo and cholesterol-reduced cheeses were ripened for 1, 3, 5, 7, and 9 wk. The cheese-making experiment was carried out in triplicate as 3 controls and 3 cholesterol-reduced samples and each batch of cheese making was divided into different salt concentrations.

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Extraction and Determination of Cholesterol 

For the extraction of cholesterol, 1g of cheese sample was placed in a screw-capped glass tube (15mm×180mm), and 500μL of 5α-cholestane (1mg/mL) was added as an internal standard. The sample was saponified at 60°C for 30min with 5mL of 2 M ethanolic potassium hydroxide solution (Adams et al., 1986). After cooling to room temperature, cholesterol was extracted with 5mL of hexane (Adams et al., 1986). The process was repeated 4 times. The hexane layers were transferred to a round-bottomed flask and dried under vacuum. The extract was redissolved in 1mL of hexane and was stored at −20°C until analysis.

Total cholesterol was determined on a silica fused capillary column (HP-5, 30m×0.32mm inner diameter×0.25μm thickness) using Hewlett-Packard 5890A gas chromatograph (Palo Alto, CA) equipped with a flame-ionization detector. The temperatures of the injector and detector were 270 and 300°C, respectively. The oven temperatures were programmed to increase from 200 to 300°C at 10°C/min and hold for 20min at 300°C. Nitrogen was used as a carrier gas at a flow rate of 2 mL/min with a split ratio of 1/50. Quantitation of cholesterol was done by comparing the peak areas with a response of an internal standard.

The percentage of cholesterol reduction was calculated as followed: cholesterol reduction (%) = 100 − (amount of cholesterol in β-CD-treated cheese × 100 / amount of cholesterol in control). Cholesterol determination for control was averaged with each batch of treatments.

Analysis of Chemical Composition and Yield of Cheese 

Cheese was analyzed for moisture, fat, salt, and protein using the methods of the Association of Official Analytical Chemists (AOAC, 1984). Cheese yield was determined as weight of cheese × 100/weight of milk.

Analysis of Short-Chain FFA 

Cheese samples (1g) were removed periodically from the cheeses at 0, 2, 4, 6, and 8 wk, extracted with diethyl ether and hexane for 2h, and eluted through a 10-mm inner diameter glass column containing neutral alumina, as described by Kwak et al. (1990). A Hewlett-Packard model 5880A gas chromatograph equipped with a flame ionization detector was used. The preparation of FFA was achieved using a 15 m×0.53mm inner diameter Nukol fused-silica capillary column (Supelco Inc., Belle-fonte, PA). The gas chromatograph was operated with helium carrier gas at 2 mL/min, hydrogen gas at 37 mL/min, and air at 300 mL/min. The column oven was programmed for an initial holding for 1 min at 110°C, heating to 180°C at 5°C/min for 10 min, and holding for 20 min. The temperature for both the injector and detector was 250°C. All qualitative analyses were done by relating each peak area of individual FFA to the peak area of tridecanoic acid as an internal standard. Each FFA was identified by the retention time of a standard.

Analysis of FAA 

Reverse phase-HPLC analysis of the FAA was performed according to the method of Izco et al. (2000). Samples were analyzed on a Waters HPLC system (Waters Corp., Milford, MA) consisting of a 600 pump and a 486 tunable absorbance detector at 254 nm. The column used was a Waters PicoTag C₁₈ reversed-phase column maintained at 46°C. For identification of amino acids, methionine sulfone was added as an internal standard. A gradient with 2 solvents was used to run the sample: solution A, consisting of 70 mM sodium acetate adjusted to pH 6.55 with acetic acid and containing 2.5% acetonitrile; and solution B, containing 45% acetonitrile, 40% water, and 15% methanol. Before each injection, the column was equilibrated with solvent A for 2 min.

Rheological Analysis 

Cylindrical samples (2cm diameter×4.5cm height) were cut, and force-distance curves were obtained using a Sun Rheometer (CR-200D, Sun Scientific Co., LTD., Tokyo. Japan) with a crosshead of 50 nm/min and a chart speed of 100mm/min. From these curves, the basic characteristics of the texture profile were determined, including hardness, elasticity, cohesiveness, gumminess, and chewiness. The point of greatest force during the first compression was the hardness. The extent to which the sample returned to its shape between the first and second compressions was the elasticity. The ratio of the area under the second compression curve was the cohesiveness. Gumminess and chewiness were calculated as hardness × cohesiveness and gumminess × elasticity, respectively.

Sensory Analysis 

For the sensory test, cholesterol-reduced cheese was stored at 4°C for 0, 2, 4, 6, and 8 wk. A 10-member trained panel evaluated randomly coded Cheddar cheese. The texture, color, flavor, and taste were evaluated on a 7-point scale (1 = very weak, 2 = slightly weak, 3 = weak, 4 = moderate, 5 = strong, 6 = slightly strong, and 7 = very strong). A randomized, balanced, complete block design was used (Cochran and Cox, 1957) that resulted in 2 replications for all samples.

Statistical Analysis 

One-way ANOVA (SAS Institute, 1985) was used. The significance of the results was analyzed by the least significant difference test. Difference of P<0.05 was considered to be significant.

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Results and Discussion 

Global Composition 

As a first experiment, we attempted to find the optimal concentration of salt added to cholesterol-reduced Cheddar cheese to obtain chemical and rheological properties similar to those of the control cheese. In the composition of cholesterol-reduced cheese treated by crosslinked β-CD, moisture content of cheese was in the range of 41.6 to 45.1%, fat 36.3 to 37.8%, and protein 27.1 to 27.7% (Table 1). There was a significant difference between the control and the cholesterol-reduced cheese in moisture content. However, no difference was found in fat and protein contents. Treatment with β-CD increased the cheese moisture content, which resulted from a slow curd drainage usually found in reduced-fat Cheddar cheese (Metzger and Mistry, 1994). In addition, β-CD treatment may increase the incorporation of casein or other protein compounds via fat-protein network. No change in fat content indicated that cross-linked β-CD did not change the size of fat globules; therefore, no fat was released in manufacture of the cholesterol-reduced cheese.

Table 1. Gross composition, yield, and cholesterol removal for control and cholesterol-reduced (CR) cheeses with differing salt content

Cheese type	Moisture	Fat	Protein	Yield	Cholesterol removal
Control1	40.2±1.2a	37.5±3.0a	27.7±2.2a	10.1±0.1a	—
CR-1.0%2	45.1±2.1b	37.1±2.6a	27.5±1.3a	11.5±0.2b	91.9±3.3a
CR-1.5%	44.9±2.9b	36.7±1.6a	27.5±1.1a	11.8±0.2b	90.8±2.2a
CR-2.0%	43.6±1.2ab	36.3±3.1a	27.2±0.9a	12.4±0.1b	91.9±1.8a
CR-2.5%	44.7±1.0b	37.2±2.2a	27.1±1.2a	11.6±0.3b	90.6±2.2a
CR-3.0%	41.6±2.4a	37.8±1.0a	27.0±2.0a	10.9±0.2a	91.9±1.2a

Short-Chain FFA 

No specific effect of salt addition was found in production of short-chain fatty acids (Table 2). In the control cheese and cholesterol-reduced cheese with 1% salt, similar amount of individual fatty acids were found, whereas C₄ was increased in cholesterol-reduced cheeses containing 1.5% salt or greater concentrations. Total amount of short-chain FFA were similar to the control, 1, and 2.5% salt-added groups. We did not find any trend relating lipolysis to salt content in the present study.

Table 2. Short-chain free fatty acid content for control and cholesterol-reduced (CR) cheeses with differing salt content

Treatment	Short-chain FFA concentration (ppm)
	C4	C6	C8	C10	Total
Control1	2.7±0.2a	2.2±0.1a	2.4±0.2b	2.9±0.2b	10.2±0.5b
CR-1.0%2	2.8±0.2a	2.2±0.2ab	2.5±0.2b	2.7±0.1b	10.2±0.4b
CR-1.5%	3.3±0.2b	2.0±0.1a	1.6±0.1a	1.7±0.1a	8.6±0.3a
CR-2.0%	2.6±0.1a	1.9±0.1a	1.9±0.2a	1.8±0.1a	8.2±0.2a
CR-2.5%	3.3±0.1b	2.7±0.1b	1.4±0.1a	2.7±0.1b	10.1±0.2b
CR-3.0%	4.8±0.2c	2.8±0.1b	2.1±0.1ab	1.3±0.1a	11.0±0.4c

FAA 

The determination of total FAA is shown in Table 3. No difference in the FAA content was observed between control and cholesterol-reduced cheeses at the beginning of the ripening (or after manufacture), regardless the level of salt. Free amino acid content ranged from 23.7 to 31.6 μmol per g of cheese (Table 3).

Table 3. Free amino acid content for control and cholesterol-reduced (CR) cheeses with differing salt content

Treatment	Amino acid, μmol per g of cheese
	Asp	Glu	Ser	Thr	Arg	Ala	Tyr	Met	Val	Phe	Ile	Leu	Lys	Total FAA
Control1	0.62	0.47	5.24	0.27	1.27	0.42	3.67	0.38	0.35	4.58	2.42	2.85	1.17	23.7±3.5a
CR-1.0%2	0.75	0.72	3.93	0.53	2.75	2.25	4.34	0.15	0.25	2.36	2.75	3.27	3.45	27.5±2.1ab
CR-1.5%	0.37	1.62	2.30	0.64	3.12	1.24	2.75	0.33	0.64	4.47	2.91	5.55	4.21	30.2±2.7b
CR-2.0%	0.22	1.21	3.14	0.12	0.64	0.83	5.47	0.14	0.60	3.65	2.72	4.93	2.32	26.0±1.9ab
CR-2.5%	0.64	0.81	4.42	0.24	3.92	1.27	3.84	0.53	0.43	2.27	2.37	6.15	4.67	31.6±2.2b
CR-3.0%	0.83	1.15	1.65	0.22	3.97	0.97	6.32	0.47	1.37	4.25	2.59	4.47	2.45	30.7±1.5b

Rheological Characteristics 

The rheological properties of cholesterol-reduced Cheddar cheeses with different amounts of salt are shown in Table 4. Rheological properties in the cholesterol-reduced cheeses containing 1.0% salt were similar to those in the control except elasticity and chewiness. The control and 1% salt-added cholesterol-reduced cheeses showed significantly higher hardness and lower chewiness scores compared with the other cheeses. The cohesiveness scores were similar in the control, 1% salt-added, and 3% salt-added cheeses, but others were significantly different. Elasticity scores were significantly higher in all cholesterol-reduced cheeses regardless of salt content. The gumminess score for the 1% salt-added cholesterol-reduced cheese was the lowest score of all the types of cheeses. Based on these results, we found that cholesterol-reduced cheeses with 1% salt were the most similar to control cheeses.

Table 4. Rheological properties for control and cholesterol-reduced (CR) cheeses with differing salt content

Treatment	Hardness (g)	Elasticity	Cohesiveness	Gumminess	Chewiness
Control1	145.8±4.2c	57.0±2.1a	43.5±0.9a	97.8±3.0b	49.3±3.8a
CR-1.0%2	155.9±5.4c	72.7±3.0b	43.4±2.3a	63.6±2.1a	56.3±4.9a
CR-1.5%	122.2±3.2b	81.7±3.7bc	67.9±2.8c	84.0±3.2ab	69.2±3.2b
CR-2.0%	123.8±2.2b	90.6±6.1c	60.3±1.3bc	92.9±5.2b	85.5±2.2c
CR-2.5%	129.0±2.7b	85.7±4.6bc	56.6±3.2b	87.6±4.1ab	89.4±4.0c
CR-3.0%	101.5±3.9a	65.6±1.2b	43.3±4.0a	100.0±2.9c	94.8±3.2d

In general, the values for the texture profile analysis parameters hardness, cohesiveness, springiness, and chewiness decreased as ripening progressed (O’Mahony and McSweeney, 2005). It is known that moisture content and extent of primary proteolysis influence the rheological properties of cheese (Guinee, 2003). There was a significant (P<0.05) reduction in the hardness of cholesterol-reduced cheeses except for 1.0% salt cheeses (O’Mahony and McSweeney, 2005). The significant (P<0.05) reduction in hardness (i.e., softening) of the cholesterol-reduced cheese was due to the greater moisture content (Creamer and Olson, 1982).

Sensory Characteristics 

The sensory attributes of cholesterol-reduced Cheddar cheese are shown in Table 5. The most significant difference was found in rancidity and off-flavor characteristics between the control and cholesterol-reduced cheese. Both rancidity and off-flavor in the cholesterol-reduced cheese were significantly greater than those in the control. Bitterness also showed higher scores in all the cholesterol-reduced cheeses except for 1% added cheeses. In texture properties, both granularity and spreadability of cheeses with different levels of salt showed similar scores to the control. However, smoothness score in the cholesterol-reduced cheeses was higher than in the control.

Table 5. Sensory characteristics for control and cholesterol-reduced (CR) cheeses with differing salt content

Treatment	Appearance	Flavor			Texture
	Yellow color	Rancidity	Bitterness	Off-flavor	Granularity	Spreadability	Smoothness
Control1	3.7±0.1b	1.4±0.1a	1.6±0.1a	1.1±0.1a	3.0±0.1a	3.3±0.1ab	1.9±0.1a
CR-1.0%2	2.4±0.1a	2.4±0.1b	1.7±0.1×	2.1±0.1b	3.7±0.2ab	3.3±0.1ab	3.4±0.1b
CR-1.5%	2.3±0.1a	2.3±0.1b	2.9±0.2b	2.1±0.1b	4.4±0.2b	3.9±0.1b	3.6±0.2b
CR-2.0%	2.0±0.1a	2.4±0.1b	2.6±0.1b	1.9±0.1ab	3.7±0.2ab	3.4±0.1ab	3.4±0.2b
CR-2.5%	2.0±0.1a	2.1±0.1b	2.9±0.2b	2.3±0.1b	3.1±0.1a	2.3±0.1a	2.9±0.1ab
CR-3.0%	2.1±0.1a	2.3±0.1b	2.4±0.1b	2.0±0.1b	3.7±0.2ab	3.9±0.2b	4.1±0.2c

Ripening Study 

In the subsequent experiment, cholesterol-reduced cheeses containing 1% salt were compared with conventional control Cheddar cheeses during the ripening process. Ripening time was fixed at 9 wk for cholesterol-reduced cheeses and at 8 mo for control cheeses.

Short-Chain FFA 

The production of short-chain FFA was considered to be an important aspect of this study. The production of short-chain FFA in the control and cholesterol-reduced cheeses during storage is shown in Table 6. The total amount of short-chain FFA was significantly lower in the cholesterol-reduced cheese treated by the cross-linked β-CD at early stages of ripening, for example, at 3 and 5 wk compared with the control at 2 and 4 mo ripening (P<0.05). However, it increased sharply after 7 and 8 wk of ripening, reaching similar values of those of control cheeses that ripened for 6 and 8 mo. In the control, the amount of total short-chain FFA increased from 9.17 to 98.64 ppm in 8 mo, but it increased from 10.22 to 108.93 ppm for the cholesterol-reduced Cheddar cheese at only 9 wk of ripening. These results indicate that the cholesterol-reduced Cheddar cheese ripening by crosslinked β-CD accelerated faster than that with no treatment. With regard to FFA production, we may assume that small particles of fat due to β-CD treatment can be easily released from cheese curds in the process of cheese manufacture.

Table 6. Short-chain fatty acid content for control (R) and cholesterol-reduced (CR) cheeses ripened at 5°C

Treatment	Short-chain FFA concentration (ppm)
	C4	C6	C8	C10	Total
CR-1 wk1	3.8±0.2a	2.7±0.2a	3.5±0.1a	3.6±0.2a	13.5±0.6a
R-0 mo2	2.7±0.2a	2.2±0.1a	2.4±0.2a	2.9±0.2a	10.2±0.5a
CR-3 wk	8.8±1.0b	4.2±0.2a	5.5±1.1a	5.6±0.4a	23.9±4.3ab
R-2 mo	14.0±2.2bc	10.3±1.2b	8.0±0.9ab	12.1±1.7b	44.2±5.2b
CR-5 wk	23.1±3.0c	12.1±2.0b	9.4±0.9ab	17.1±1.5b	61.7±5.6c
R-4 mo	24.8±4.1c	14.5±1.7b	12.3±2.1b	18.6±2.0bc	70.2±3.2c
CR-7 wk	30.7±3.1cd	15.1±2.9b	17.1±1.8bc	22.5±1.9c	85.4±5.0d
R-6 mo	34.6±3.2cd	17.2±3.2bc	13.9±2.5b	24.2±2.0c	89.9±5.1d
CR-9 wk	37.8±2.2d	18.2±2.0bc	22.0±1.3c	30.0±2.1d	108.9±6.4e
R-8 mo	31.2±3.2cd	20.7±1.2c	19.9±2.8bc	27.0±2.3cd	98.6±7.7e

FAA 

The production of total FAA during ripening is shown in Table 7. The principal amino acids present in both cheeses during ripening were tyrosine, phenylalanine, leucine, and lysine (Table 7). In agreement with these results, leucine and phenylalanine were also reported to be the most abundant FAA in miniature Cheddar-type cheeses ripened at 8°C for 2 mo (O’Mahony et al., 2003). Shakeel-Ur-Rehman et al. (2004) also reported glutamic acid, valine, leucine, and phenylalanine to be the most abundant FAA in Cheddar cheeses ripened at 8°C for 180 d.

Table 7. Free amino acid content for control (R) and cholesterol-reduced (CR) cheeses ripened at 5°C

Treatment	Amino acid, μmol per g of cheese
	Asp	Glu	Ser	Thr	Arg	Ala	Tyr	Met	Val	Phe	Ile	Leu	Lys	Total FAA
CR-1 wk1	0.79	0.88	4.13	0.59	2.91	2.25	4.64	0.19	0.31	4.15	2.95	4.56	4.11	32.6±8.0a
R-0 mo2	0.62	0.47	5.24	0.27	1.27	0.42	3.67	0.38	0.35	4.58	2.42	2.85	1.17	23.7±3.5a
CR-3 wk	1.98	2.01	4.65	0.93	3.12	1.77	13.14	1.87	0.89	13.28	2.94	12.82	5.14	64.5±7.9b
R-2 mo	2.99	2.15	4.45	1.21	2.92	1.18	7.51	1.49	1.14	13.12	3.81	8.62	7.19	57.8±4.2b
CR-5 wk	3.42	3.24	4.60	1.72	3.99	2.09	13.66	1.75	1.39	15.32	2.91	15.09	6.02	75.2±8.0c
R-4 mo	3.37	2.44	4.47	1.53	3.32	1.35	12.02	1.50	1.11	17.46	3.29	13.13	8.48	73.5±6.1c
CR-7 wk	3.96	3.13	4.94	1.82	4.09	1.61	14.98	2.09	1.25	18.01	3.21	18.21	12.60	89.7±6.8d
R-6 mo	3.86	2.85	4.59	1.27	1.97	1.16	15.62	1.79	1.21	19.76	3.19	16.39	11.62	85.2±12.5d
CR-9 wk	5.11	3.39	5.42	1.09	4.63	2.37	17.88	2.32	1.51	22.71	3.23	20.96	15.30	105.6±10.2e
R-8 mo	4.37	3.20	4.51	1.63	3.26	1.63	18.81	2.18	1.22	24.75	3.21	19.24	13.89	101.7±11.3e

The cheeses made from β-CD–treated cream produced slightly lower amounts of individual FAA at an early stage of ripening period (1 and 3 wk) compared with the control (0 and 2 mo), respectively. Total amount of FAA was 104.55 μmol per g of cheese in the control and 101.73 μmol per g of cheese in the cholesterol-reduced cheese after 8 mo and 9 wk ripening periods, respectively. After 7 and 9 wk ripening, the total amount of FAA in cholesterol-reduced cheeses reached similar amounts of FAA to those of control cheeses at 6 and 8 mo. This suggests that the cheese made from β-CD-treated cream showed accelerated ripening in terms of FAA production, partly due to the accelerated proteolysis.

Proteolysis in cheese is caused by the action of the rennet retained in the curd, plasmin of the milk, and proteases and peptidases from the starter cultures used. Protease activity leads to a large amount of peptides, the so-called soluble-nitrogen fraction in a cheese. These peptides are further degraded to small peptides and FAA, the amino-nitrogen fraction in cheese. Protease and peptidase activities are dependent on the starter culture used. For this reason a lot of attention has been paid to the use of starter cultures and lactic acid bacteria, which enhance ripening and flavor formation in cheese (Smit et al., 2000; Yvon, 2006).

Rheological Characteristics 

The effect of β-CD treatment on rheological properties of the cholesterol-reduced cheese is shown in Table 8. In hardness, the control showed a significant and continuous increase during the 8-mo ripening period from 145.50 to 555.88, whereas that in a cholesterol-reduced cheese increased slightly during 9 wk of ripening from 153.8 to 279.4. Even though hardness increased in the cholesterol-reduced cheese hardness for 9 wk ripening, it could not reach similar values to control ripened for 8 mo. This result may be attributed by the high amount of moisture in the cholesterol-reduced Cheddar cheese.

Table 8. Rheological properties for control (R) and cholesterol-reduced (CR) cheeses ripened at 5°C

Treatment	Hardness	Elasticity	Cohesiveness	Gumminess	Chewiness
CR-1 wk1	153.9±5.0a	70.7±5.5c	44.3±4.7b	63.6±2.0b	56.3±2.4a
R-0 mo2	145.8±4.2a	57.0±2.1b	43.5±0.9b	97.8±3.0c	49.3±3.8a
CR-3 wk	168.2±7.2a	51.5±8.9b	45.0±2.7b	94.3±8.2c	94.7±3.2c
R-2 mo	237.5±23.2ab	61.0±13.0b	41.8±3.0b	63.0±3.8b	80.8±6.0b
CR-5 wk	164.8±19.8a	59.8±10.2b	42.0±3.5b	81.9±6.3bc	77.8±5.2b
R-4 mo	434.3±17.0c	29.5±7.5a	33.8±5.2ab	56.3±3.2ab	77.0±8.9b
CR-7 wk	216.8±9.7ab	55.8±5.8b	55.8±3.7c	65.4±8.1b	61.0±5.6ab
R-6 mo	537.9±27.9d	26.9±4.0a	24.4±1.2a	52.2±2.6ab	71.5±3.1b
CR-9 wk	279.4±13.2ab	46.2±3.2b	53.6±3.1c	64.5±7.0b	50.3±2.7a
R-8 mo	555.9±33.2d	22.4±3.1a	17.9±1.2a	42.7±5.1a	63.4±6.5ab

In the cholesterol-reduced cheese, elasticity decreased from 70.7 to 46.2 during the 9-wk ripening period. Elasticity was always higher in the cholesterol-reduced cheese compared with the control, except at 3 wk of ripening. Cohesiveness value in the cholesterol-reduced cheese was stable up to 5 wk and increased thereafter, whereas it was continuously decreased in the control. In the cholesterol-reduced cheese, the highest gumminess was found at 3 wk and decreased thereafter. Chewiness value in the cholesterol-reduced cheese up to 5 wk was greater than that of the control up to 4 mo; however, it was reversed thereafter. Based on these results, the elasticity, cohesiveness, and gumminess in the cholesterol-reduced cheese at 5 wk ripening were significantly higher than those in the control at 4 mo ripening. However, the significant low hardness scores in the cholesterol-reduced cheese needs to be studied more.

Sensory Characteristics 

The sensory attributes of cholesterol-reduced cheese are shown in Table 9. In appearance, yellow color appeared to be greater in the control than in the cholesterol-reduced cheese at the beginning of the ripening. However, color was increased dramatically over score 3 in the cholesterol-reduced cheese, even though it was still lower compared with that of the control.

Table 9. Sensory characteristics for control (R) and cholesterol-reduced (CR) cheeses ripened at 5°C

Treatment	Appearance	Flavor			Texture
	Yellow color	Rancidity	Bitterness	Off-flavor	Granularity	Spreadability	Smoothness
CR-1 wk1	2.2±0.1a	2.7±0.1b	1.9±0.1a	2.1±0.2b	3.5±0.2ab	3.3±0.2a	3.4±0.2b
R-0 mo2	3.7±0.3b	1.4±0.1a	1.6±0.1a	1.1±0.1a	3.0±0.1a	3.3±0.1a	1.9±0.1a
CR-3 wk	2.9±0.2ab	3.3±0.2bc	2.7±0.2b	2.6±0.2b	3.3±0.3a	3.1±0.2a	3.1±0.3b
R-2 mo	4.1±0.3bc	1.7±0.1a	1.9±0.1a	1.6±0.2ab	4.9±0.2c	4.7±0.3c	3.3±0.3b
R-4 mo	4.1±0.3bc	3.3±0.3bc	3.3±0.2bc	3.7±0.3c	5.0±0.4c	4.7±0.4c	3.6±0.2b
CR-5 wk	3.1±0.1ab	3.3±0.2bc	3.9±0.2c	2.1±0.1b	4.3±0.3bc	4.0±0.4ab	3.7±0.3b
CR-7 wk	3.3±0.2ab	3.7±0.2c	4.0±0.4c	3.1±0.2bc	4.0±0.3b	3.9±0.3ab	3.7±0.2b
R-6 mo	4.6±0.4c	4.4±0.4cd	4.9±0.3d	3.7±0.3c	4.3±0.4bc	4.3±0.3b	3.3±0.3b
CR-9 wk	3.7±0.2b	4.7±0.3d	4.7±0.3d	2.9±0.3bc	5.1±0.3c	5.1±0.4c	4.3±0.3c
R-8 mo	4.4±0.3c	4.4±0.4cd	5.9±0.4e	3.6±0.4c	5.3±0.4c	4.9±3.2c	3.4±0.2b

In flavor properties, cholesterol-reduced cheeses showed a sharp increase of rancidity, bitterness, and off-flavor after 3 wk of ripening, exceeding the values in control cheeses ripened for 2 mo. However, after 5 wk and 4 mo, the values were mostly lower in the cholesterol-reduced cheese compared with those in the control.

Another aspect we found in the study was an increase of bitterness score in the cholesterol-reduced cheese at 3 wk of ripening and thereafter. This was probably due to a significant difference of amino acid production in the cholesterol-reduced cheese. Therefore, we may suggest that crosslinked β-CD treatment resulted in enhanced proteolysis, which could be one reason among other unknown factors. The larger increase in total and individual amino acids, including bitter amino acids, observed through the ripening period may reflect greater peptidase activity in the cholesterol-reduced cheese than in the control. Proteolysis in cheese during ripening results in an increase in peptides, which is directly related to bitterness (Fernandez-Espla and Fox, 1998; Smit et al., 2000). In texture properties, not much difference was found in granularity and spreadability between 1 wk of the cholesterol-reduced cheese and 0 mo of the control. However, the smoothness score in the cholesterol-reduced cheese was significantly higher than the control. The smoothness score was maintained throughout the ripening period in the cholesterol-reduced cheese. The present study showed the first evidence that β-CD treatment may provide an accelerated ripening effect on Cheddar cheese; therefore, further study which will focus on how β-CD affects the ripening process will be needed.

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Acknowledgments 

This study was supported by the Brain Korea 21 Project in Seoul, Republic of Korea.

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References 

1. Adams ML, Sullivan DM, Smith RL, Richer EF. Evaluation of direct saponification method in determination of cholesterol in meats. J. Assoc. Anal. Chem. 1986;69:844–846
   • View In Article
2. AOAC. 1984. Official Methods of Analysis. 4th ed. Association of Official Analytical Chemists, Arlington, VA.
   • View In Article
3. Aston JW, Giles JE, Durward HG, Dully JR. Effect of elevated ripening temperature on proteolysis and flavour development in Cheddar cheese. J. Dairy Res. 1985;52:565–572
   • View In Article
   • CrossRef
4. Cochran WG, Cox GM. Experimental Designs. New York, NY: John Wiley & Sons; 1957;
   • View In Article
5. Creamer LK, Olson NF. Rheological evaluation of maturing Cheddar cheese. J. Food Sci. 1982;47:631–646
   • View In Article
   • CrossRef
6. Fernandez-Espla MD, Fox PF. Effect of adding Propiobacterium shermanii NCDO 853 or Lactobacillus casei ssp. casei IFPL 731 on proteolysis and flavor development of Cheddar cheese. J. Agric. Food Chem. 1998;46:1228–1234
   • View In Article
   • CrossRef
7. Fox PF. Proteolysis during cheese manufacture and ripening. J. Dairy Sci. 1989;72:1379–1385
   • View In Article
   • Abstract
   • Full-Text PDF (2253 KB)
   • CrossRef
8. Fox PF. Acceleration of cheese ripening. Food Biotechnol. 1989;2:133–185
   • View In Article
9. Fox PF, McSweeney PLH. Chemistry and biochemistry of cheese and fermented milks. In:  Fox PF,  McSweeney PLH editor. Dairy Chemistry and Biochemistry. London, UK: Blackie Academic & Professional; 1998;p. 379–436
   • View In Article
10. Guinee TP. Role of protein in cheese and cheese products. In:  Fox PF,  McSweeney PLH editor. Advanced Dairy Chemistry. New York, NY: Kluwer Academic/Plenum Publishers; 2003;p. 1083–1174
    • View In Article
11. Han EM, Kim SH, Ahn J, Kwak HS. Cholesterol removal from homogenized milk with crosslinked β-cyclodextrin by adipic acid. Asian-Aust. J. Anim. Sci. 2005;18:1794–1799
    • View In Article
12. Izco JM, Irigoyen A, Torre P, Barcina Y. Effect of the activity levels of the added proteolytic enzyme mixture on free amino acids in ripening Ossau-Iraty cheese. J. Chromatogr. A. 2000;881:69–79
    • View In Article
    • MEDLINE
    • CrossRef
13. Kwak HS, Jeon IJ, Park J. Effects of food grade porcine pancreatic lipase on the production of short-chain fatty acids and its contribution. Korean J. Food Sci. Technol. 1990;22:248–254
    • View In Article
14. Kwak HS, Jeon IJ, Perng SK. Statistical patterns of lipase activities on the release of short-chain fatty acids in Cheddar cheese slurries. J. Food Sci. 1989;54:1559–1560
    • View In Article
    • CrossRef
15. Kwak HS, Jung CS, Shim SY, Ahn J. Removal of cholesterol from Cheddar cheese by β-cyclodextrin. J. Agric. Food Chem. 2002;50:7293–7298
    • View In Article
    • MEDLINE
    • CrossRef
16. Law BA. The accelerated ripening of cheese. In:  Davies FL,  Law BA editor. Advances in the Microbiology and Biochemistry of Cheese and Fermented Milk. London, UK: Elsevier Applied Science; 1984;p. 209–228
    • View In Article
17. Lucey JA, Johnson ME, Horne DS. Perspectives on the basis of the rheology and texture properties of cheese. J. Dairy Sci. 2003;86:2725–2743
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (1421 KB)
    • CrossRef
18. McSweeney PLH. Biochemistry of cheese ripening. Int. J. Dairy Technol. 2004;57:127–144
    • View In Article
19. Metzger LE, Mistry VV. A new approach using homogenization of cream in the manufacture of reduced fat Cheddar cheese. 1. Manufacture, composition, and yield. J. Dairy Sci. 1994;77:3506–3515
    • View In Article
    • Abstract
    • Full-Text PDF (792 KB)
    • CrossRef
20. Morris HA. Cheese ripening research—Trends and perspectives. J. Dairy Sci. 1978;61:1198–1204
    • View In Article
    • Abstract
    • Full-Text PDF (553 KB)
    • CrossRef
21. O’Keeffe AM, Fox PF, Daly C. Proteolysis in Cheddar cheese: Role of coagulant and starter bacteria. J. Dairy Res. 1978;45:465–471
    • View In Article
    • CrossRef
22. O’Mahony JA, Sousa MJ, McSweeney PLH. Proteolysis in miniature Cheddar-type cheeses made using blends of chymison and Cynara cardunculus proteinase as coagulant. Int. J. Dairy Technol. 2003;56:52–58
    • View In Article
23. O’Mahony JAL, McSweeney PLH. Chymison-mediated proteolysis, calcium solubilization, amd texture development during the ripening of Cheddar cheese. J. Dairy Sci. 2005;88:3101–3114
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (593 KB)
    • CrossRef
24. O’Reilly CE, Kelly AL, Oliveira JC, Murphy PM, Auty MAE, Beresford TP. Effect of varying high-pressure treatment conditions on accerelation of ripening of cheddar cheese. Innov. Food Sci. Emerging Technol. 2003;4:277–284
    • View In Article
25. SAS Institute. 1985. SAS Users Guide: Statistics. Version 5 ed. SAS Inst. Inc., Cary, NC.
    • View In Article
26. Shakeel-Ur-Rehman , Waldron D, Fox PF. Effect of modifying lactose concentration in cheese curd on proteolysis and in quality of Cheddar cheese. Int. Dairy J. 2004;14:591–597
    • View In Article
27. Smit G, Verheul A, van Kranenburgm R, Ayad E, Siesen R, Engels W. Cheese flavor development by enzymatic conversions of peptides and amino acids. Food Res. Int. 2000;33:153–160
    • View In Article
28. Walstra, P., T. J. Geurts, A. Noomen, A. Jellema, and M. A. J. S. van Boekel. 1999. Cheese ripening and properties. Pages 630–638 in Principles of Milk Properties and Processes. P. Walstra, T. J. Geurts, A. Noomen, A. Jellema, and M. A. J. S. van Boekel, ed. Marcel Dekker Inc., New York, NY.
    • View In Article
29. Yokoyama, H., N. Sawamura, and N. Motobatashi, inventors. 1992. Method for accelerating cheese ripening. Eur. patent 0 469 857.
    • View In Article
30. Yvon M. Key enzymes for flavour formation by lactic acid bacteria. Aust. J. Dairy Technol. 2006;61:88–96
    • View In Article