Potassium (1:1) Chloride and Low Sodium Chloride Concentrations on Quality of Cheddar Cheese1

Effect of Sodium/Potassium (1:1) Chloride and Low Sodium Chloride Concentrations on Quality of Cheddar CheeseI R. C. LINDSAY, S. M. H A R G E T T , and C. S. BUSH Department of Food Science University of Wisconson Madison 53706

difficult to meet the recommended salt intake with a diet composed of processed and manuCheddar cheese samples containing factured foods presently available. Consumers either 1.25, 1.5, or 1.75% sodium chloare becoming increasingly aware of sodium and ride or 1.25 or 1.5% sodium/potassium potassium in foods and the apparent relationchloride (1:1, molar basis) were manuship between hypertension and ingestion of factured from a split lot of cheese curd. sodium (1, 8). Therefore, consumers may exert Sensory analysis of the cheeses through pressures on the government and food industry 9 mo aging at 3°C showed that all samto provide sodium and potassium labeling of ples were acceptable although some bitterfoods (30). This pressure can be expected to ness was observed, especially in the cheese include that for provision of acceptable, recontaining 1.5% mixture. Body and texduced sodium alternatives to traditional prodture of samples were firm, reflecting the ucts. In anticipation of this action, some cheese 35% moisture content of the samples. manufacturers already have begun marketing Cheeses containing potassium chloride had products to meet the developing demand (10). higher contents of free fatty acids than Several unresolved issues surrounding the those with only sodium chloride. Mean final development of guidelines and regulations consumer preference scores showed that for sodium and potassium in foods were dissome consumers recognized and preferred cussed in detail during a conference sponsored the fuller salty taste of cheeses with by the American Medical Association (28). higher sodium chloride concentrations Major concerns about suggested lowering of over those with the small amounts or the sodium chloride content in some foods include mixture. Unsalted Cheddar cheese was the possibility of losing the technological disliked strongly by a laboratory panel. functionality and preservative effects of sodium chloride in these foods, especially those preINTRODUCTION served by fermentation (18). Salt strongly The cheese industry may find it advisable to influences the ripening of Cheddar cheese (7, consider voluntarily decreasing salt where 26), which is expressed in terms of rates of possible "in cheeses to maintain consumer flavor and body development (15, 24) as well as demands now experienced for cheeses. Pro- quality of flavors developed (9, 22, 25). posed dietary goals for the US include a recAlternatives for foods with reduced sodium ommendation for reducing sodium chloride include simple lowering of concentrations of intake from around 15 g per day currently NaCI, partial substitution of NaC1 with other ingested by adults (2, 20) to 8 g (4) and the US salts, such as KC1, and combinations of the Food and Drug Administration has proposed aforementioned practices along with inclusion regulations requiring declaration of sodium and of other flavor modifying ingredients. A mixpotassium on food labels (3). Because salt is rare of NaCI/KC1 (1:1, molar basis) has been used so widely in foods currently, it may be commercially available on the retail market for several years, but little has been published about its potential role in processed foods. Recently, however, this NaC1/KC1 mixture has Received April 3, 1981. performed adequately at certain concentrations 1Research supported by the College of Agricul- in some canned vegetables where it improved tural and Life Sciences (Hatch No. 2400), the Sensory Analysis Laboratory, and the Cheese Research the Na/K ratio (31). Since Cheddar cheese may have less demanding requirements for high salt Institute, University of Wisconsin, Madison. ABSTRACT

1982 J Dairy Sci 65:360--370

360

EVALUATIONOF LOW-SALTCHEDDARCHEESE concentrations than some cheeses for control of microflora and biochemical processes, possibilities for reducing sodium exist. Our data were developed in an exploratory study to evaluate effects of a 1:1 NaCI/KC1 salt mixture (molar basis) and lowered NaC1 concentrations on the quality of Cheddar cheese. MATERIALS A N D METHODS Manufacture of Experimental Cheddar Cheese

Cheese was manufactured in the University of Wisconsin Dairy Products Laboratory. Whole milk (3.5% fat) was ~asteurized at 62.8°C for 30 rain, cooled to 3 lvC, and inoculated with a commercial frozen lactic cheese starter (Hansen's Redi-Set, Chr. Hansen's Laboratory, Milwaukee, WI). Single-strength calf rennet (Rennet Extract, Marschall Division, Miles Laboratories, Madison, WI) was employed. Curd was cooked at 39°C before draining and cheddaring. Cheddared curd was milled at pH 5.2 and .5% titratable acidity. Five lots of milled curd weighing 12 kg each were separated from each other and then were salted at either 1.9 or 2.5% (wt/wt) with noniodized NaCI (Cheese Salt, Diamond Crystal, St. Clair, MI) or NaC1/KC1 mixture (1:1, molar basis; Lite Salt ®, Morton's Salt Division, Morton-Norwich Products, Chicago, IL). The lower salting rate was selected because it was about 75% of the usual rate, and this degree of reduction for the NaCI/KC1 mixture has been useful in other foods for still providing salty taste while minimizing the bitter taste of KCI (5). Later analyses showed that 30 to 40% of the salts were lost with whey during mixing, hooping, and pressing. After pressing into 9-kg rectangular blocks, cheese was wrapped (Cell-O-Poly to Foil, American Can Co., Neenah, WI) and placed at 3°C (+ 1°C) for low-temperature aging. Cheese blocks were cut into 500 g pieces after 90 days and were repackaged in barrier film pouches (100 gauge Nylon/Saran/2 mil CopolymerSurlyn; < 1 CC/645 cm 2/24 h oxygen transmission rate; Curwood, Inc., New London, WI) that were sealed under reduced pressure (50 mm of Hg; Multivac Packaging Machine, Model AG1, Sepp Haggenmuller KG, Wolfertschwenden, West Germanic). Aging of cheese then was continued at 3-C until samples were removed at appropriate times for analysis.

361

Comparison samples of regular and unsalted commercial Cheddar cheese were purchased locally from a retail store. The regular cheese had been aged over 90 days, and the unsalted cheese had been aged over 60 days. Sensory Analysis Procedures

Samples were tempered by holding at ambient termperature (ca. 21°C) for 1 h before packages were opened and cheese was sliced into individual portions of ca..5 × 4 x 4 cm. Individual samples were presented to panelists on white uncoated paper plates (15 cm diameter) coded with 3-digit random numbers. For descriptive analysis, either the intermediate or the low NaC1 cheeses 'were presented both as coded and as identified reference samples. Descriptive analysis panels were composed of 21 to 27 individuals experienced in sensory evaluation procedures. Panelists were seated in individual booths equipped with running water and indoor fluorescent lighting. Water and unsalted soda crackers were provided free choice. A structured intensity of difference scale (16) and linear, semi-structured quantitative descriptive analysis scales (23) were included on ballots. The difference intensity determination required the judges to compare each coded sample with the reference and then to assess the intensity of overall difference for each pair. Separate scales were used to evaluate cheeses for saltiness, bitterness, astringency, off-flavor intensity, acidity, Cheddar cheese flavor, firmness, and overall preference. Marked judgments were coded on a seven-point basis. Consumer panelists were enlisted from the clientele of the University of Wisconsin-Madison Dairy Salesroom, and the approximate age distribution was 17 to 25 (50%), 26 to 34 (25%), 35 to 50 (20%), and over 50 yrs (5%). Each group was composed of approximately equal numbers of males and females. Approximately 150 observations were obtained for each product. Panelists were seated at individual booths in the salesroom, and samples were rated on either a seven-point hedonic scale or perceived quality scale. Data from each panel session were analyzed for differences among samples by an analysis of variance appropriate for a randomized complete block design (21). For each sensory attribute, statistical analysis provided the mean scores for Journal of Dairy Science Vol. 65, No. 3, 1982

362

LINDSAY ET AL.

each sample, the F-value for all samples, and least significant differences for sample comparisons. Chemical Analyses

Elemental analyses were by inductively coupled plasma-atomic emmission spectrometry (6; Raltech Scientific Services, Madison, WI). Measurement of pH was with a quinhydrone electrode (26). Fat and moisture were determined by official AOAC methods (12). Free fatty acids were determined by the m e t h o d reported by Woo and Lindsay (29). RESULTS A N D DISCUSSION

A summary of general compositional characteristics of the experimental cheeses is in Table 1. Total salt concentrations were calculated as chlorides from measured sodium and potassium contents of the cheeses (Table 2) and ranged from 1.25 to 1.75%. Terms of low, intermediate, and high were assigned to these salt concentrations to facilitate discussions, but amounts of salt-in commercial Cheddar cheese may reach 2%, particularly in cheese for processing. All of the experimental cheeses from the split-lot of curd contained around 35% moisture

and, therefore, were considered low-moisture samples. Each was also slightly mealy and short throughout the 9 mo aging, reflecting the low-moisture content and relatively low pH. Salt to moisture ratios (S/M) of 4 to 6 are usually recommended for best Cheddar cheese flavor development and preventing excessive proteolysis and bitterness (9, 15), and both the low NaC1 and the low NaC1/KC1 samples were below recommended. Limited microbial analysis showed that the high NaC1, high NaC1/KCI, and low NaCI/KCI samples at about 15 mo age had similar counts of about 1.2 x 106/g on plate count agar whereas the low NaCI sample had a count of 8.6 x 106/g (13). All samples were negative for Staphylococcus aureus by using Baird-Parker medium. Extensive proteolysis, characterized by a soft body and texture, was not observed for any of the experimentally prepared samples, y e t bitterness was noted for samples regardless of the type of salt. Measurement of pH revealed that experimental cheeses were similar in this regard also, although cheeses containing the KC1 mixtures appeared to show slightly higher pH than those with NaC1. Analysis of free fatty acids after 9 mo showed that the cheeses with the NaC1/KCI

TABLE 1. Analytical data for experimental Cheddar cheese samples manufactured from a split-lot of milled curd.

Measurement Total salt (NaCI -- KCI, %)a pH (at 9 mo) Fat (at 9 mo, %) Moisture (at 9 mo, %) Salt/moisture levelb Free fatty acids (at 9 mo, ppm) Butyric Caproic Capryllic Capric Laurie Myristic Palmitic Stearic, oleic, linoleic Total

Low NaC1 1.25 5.00 34.0 35.5 3.5 <4 9 6 25 32 72 191 176 515

Experimental cheese samples Intermediate High Low NaCI NaC1 NaCI/KC1 1.50 5.00 34.0 35.3 4.2 <4 5 4 25 30 124 260 177 629

1.75 5.00 34.0 35.3 4.9 • .

.C

1.25 5.01

34.3 34.7 3.6 <4 20 6 31 35 105 311 458 970

acalculated as chloride salts from Na and K contents. bsalt/moisture × 100; Lawrence and Giles (15); calculated using indicated total salt levels. CData not available. Journal of Dairy Science Vol. 65, No. 3, 1982

Intermediate NaCI/KCI 1.50 5.05

34.2 35.1 4.3 <4 15 7 33 48 106 325 389 927

EVALUATION OF LOW-SALT CHEDDAR CHEESE

salt mixtures contained higher total concentrations than those with NaC1 only, and this was the case especially for the C] 6 and C] s members. These results indicate more extensive lipase activity in those cheeses and agree with (24). However, elevated butyric acid was not observed as was reported by Thakur et al. (24) for unsalted Cheddar cheese• These workers reported butyric acid up to 109 mg/kg of unsalted cheese and 82 mg/kg for salted cheese after 3 mo aging at 9 to 10°C. Because the analytical procedure used by Thakur et al. (24) extensively distorted data by induced hydrolysis (29), and because rancid flavors were not reported for cheeses by the authors, it can be assumed that short-chain free fatty acid concentrations were substantially lower than those reported. Analytical data and nutritionally-related calculations for sodium and potassium in the cheeses are provided in Table 2, and results for other elements are summarized in Table 3. For comparison, data in USDA Handbook No. 8 (27) for average Cheddar cheese also are shown. For experimental cheeses, lowering the NaC1 concentration to 1.25% substantially reduced the sodium amount per serving of cheese as compared to usual salt concentrations (ca. 2%), but the ratio of Na to K remained high. However, use of the NaCI/KC1 mixture effectively brought the Na:K ratio near the desired .5 on a gravimetric basis, or 1.0 on a molecular basis (11, 20), while also greatly reducing the amount of sodium per serving compared to usual Cheddar cheese. Data for other elements measured in the cheeses showed that the samples were similar (Table 3), and only copper concentration varied among samples. Apparently, salts employed provided most of the copper; the unsalted cheese had a low concentration, and the amount in salted samples paralleled the amount of salt added. Concentrations of iron were uniformly much lower than that given in USDA Handbook No. 8 (27). Evaluation of experimental cheeses by experienced dairy products judges provided general characterizations of the flavor and body of the samples over the study period. The body of all samples was considered short and mealy throughout the 9 mo of aging, and it was scored from 3 to 4 on the American Dairy Science Association (ADSA) scorecard scale. The ADSA flavor scores for the intermediate NaC1/KC1 and

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I Journal of Dairy Science Vol. 65, No. 3, 1982

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T A B L E 4. S u m m a r y o f m e a n scores for t h e d e s c r i p t i v e s e n s o r y a n a l y s i s o f e x p e r i m e n t a l C h e d d a r c h e e s e a f t e r 3 m o aging. Sample attributes

Samples

Intensity of difference a

Saltiness intensityb

Bitterness IntensityC

Astringencyd

Off-flavor intensitye

Acidity intensityf

Cheddar cheese flavorg

Firmness h

Overall preference i

(Mean scoresJ) Panel session 1 L o w NaC1 (1.25%) (reference) L o w NaCI/KCI (1.25%) Commercial unsalted Panel session 2 I n t e r m e d i a t e NaCI (1.5%) ( r e f e r e n c e ) High NaCI (1.75%) I n t e r m e d i a t e NaCI/KCI (1.5%)

<

1.70 x 2.57Y 6.23 z

3.83x 3.52 x 2.04Y

2.95 x 3.42 x 3.51 x

3.52 x 3,49 x 3.01X

2.40 x 2.57 x 4.26Y

3.82 x 3.62 x 2.68Y

4.33 x 4,23 x 2.16Y

4.91 x 4.69 x 2.27Y

4.68 x 4.29 x 2.75Y

2,51 x 2.51x

3.30x,y 3.50x

2.75 x 2.95 x

3.46 x 3.44 x

2.42 x 2.18 x

3.50 x 3.79 x

3,89 x 4,01 x

4.47 x 4.90 x

4.24 x 4.01 x

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would be reduced greatly compared to salted cheeses. The salted cheese samples were remarkably similar (Table 4) after 3 mo aging, but in each of the salt concentration-based groupings, it was apparent that KC1 was influencing perceived flavor properties of those containing this salt. Scores indicated that KCl-contalning samples were slightly less salty and slightly more bitter. The mean preference scores also indicated a trend for lower preference scores for these samples compared to salted counterparts. Voluntary comments from some panelists indicated a perception of unusual less full, salty flavors and slightly astringent mouthfeel sensations which were apparently attributable

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flavor intensity than the intermediate NaC1 sample. The intermediate NaC1/KC1 sample was

also more bitter and exhibited more off-flavor than the intermediate NaC1 sample, and the body of the KCl-containing sample also was significantly softer than its NaC1 counterpart. These combined properties resulted in a significantly lower overall preference score for the intermediate NaC1/KCI sample than for either

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TABLE 6. S u m m a r y of mean scores for the descriptive sensory analysis of e x p e r i m e n t a l Cheddar cheese after 9 m o aging. Sample a t t r i b u t e s

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I n t e n s i t y of difference a

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Bitterness intensity

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Firmhess

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O 3.99 x

4.53 x 3.90x

3.97x 3.97x

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4.16 x 4.31 x

4.42 x 4.38 x

4.15 x 4.28 x

4.25 x

3.97 x

4.18 x

3.59Y

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3.50 x 3.57 x

2.80 x 3.00 x

3.82x 3.71 x

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2.38 x 2.71x,y

3.49 x 3.63 x

3.30 x 3.29 x

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3.04Y

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ascales as given in Table 4. bn -- 26 and 24, respectively. x'YMean scores in same c o l u m n w i t h i n a panel session w i t h same superscript are n o t significantly different at 5%.

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LINDSAY ET AL.

and a nearly significant higher bitterness intensity. However, slight bitterness was noted by some panelists in both NaCI samples also. Consumer preference evaluations also were conducted for selected experimental Cheddar cheese samples after 9 mo aging. Because the intermediate NaC1 sample exhibited the best overall Cheddar cheese character of the samples, it was selected for inclusion in further comparisons with lower-salt cheeses. The data in Table 7 show that the intermediate NaC1 sample was significantly preferred over both the low NaC1/KC1 sample (panel session 1) and the low NaC1 sample (panel session 2). Comparison of preference mean scores between panels show that the consumer groups reacted similarly to the low NaC1 and the NaCI/KC1 samples when each was evaluated against the intermediate NaC1 sample. Voluntary consumer panelist comments from the intermediate NaC1 and low NaC1/KCI sample comparison indicated that the low NaCI/KC1 sample was frequently flat and bland whereas the intermediate NaC1 sample elicited frequent comments about its fuller and better flavor. The similar comparison of the two NaC1 cheeses yielded a substantial number of voluntary responses that the low NaC1 was bland and sharp or acidic, but few specifically noted a fuller flavor for the intermediate NaCI sample as had occurred in the comparison

with the low NaCI/KC1 sample. Sensory analyses to this point had involved direct comparisons of samples and had indicated that reduced concentrations of both NaC1 and NaCI/KCI in samples caused lowered overall preference scores. The final testing involved evaluation of consumer assessment of the relative perceived quality of either intermediate or low NaC1 cheese samples based on actual tasting of one of the samples and recalling how the usually purchased medium aged Cheddar cheese would compare to that sample. In Table 8 the magnitude of the mean attitudinal score for the intermediate NaC1 sample was larger than that for the low NaC1 sample. A b o u t 85% of the panelists evaluating the intermediate NaC1 sample found this sample just as good or better than the usual medium Cheddar cheese. However, a smaller number or about 65% of the panelists evaluating the low NaC1 sample found it as good or better than the usual medium Cheddar cheese. Since foods are usually n o t directly compared in actual consumption settings, this evaluation result should reflect a reasonably accurate consumer response to low NaC1 cheese (14). Whereas some consumer resistance was noted for this sample, it appeared limited and subtle. Based on the earlier comparisons, it also seems reasonable to infer that cheeses simitar to each of the lowered NaCI

TABLE 7. Response frequencies and mean scores for consumer preference panel evaluation of experimental Cheddar cheese after 9 mo aging.

Preference rating score

Like very much (7) Like moderately (6) Like slightly (5) Neither like nor dislike (4) Dislike slightly (3) Dislike moderately (2) Dislike very much (1)

Panel session 1 samples Intermediate Low NaCI NaC1/KCI (1.5%) (1.25%)

39 51 30 14 16 1 0 5.53 x

Panel session 2 samples Intermediate NaCI (1.5%)

(Frequency of responses ) 22 42 51 59 36 28 13 8 16 11 7 2 6 0 Mean scoresa 5.03Y 5.71 x

an = 150 each session. x'YMean scores with the same superscript within a panel session are not significantly different at 5%. Journal of Dairy Science Vol. 65, No. 3, 1982

Low NaCI (1.25%)

26 49 27 17 2 6 1 5.09Y

EVALUATION OF LOW-SALTCHEDDAR CHEESE

369

TABLE 8. Response frequencies and mean scores for a consumer attitude evaluation of experimental Cheddar cheese after 9 mo aging. Rating by Recalled comparison to the usual mediumaged Cheddar cheesea

Panel session 1 Low NaCI (1.25%)

Score

Panel session 2 Intermediate NaCI (1.5%)

(Frequency of responses) Much better than Moderately better than Slightly better than Just as good as Slightly poorer than Moderately poorer than Much poorer than

7 6 5 4 3 2 1

5 16 15 12 16 6 1

6 23 14 22 7 5 0 (Mean attitudinal scoresb) 4.79

4.44 aAssigned after tasting appropriate experimental sample.

bData between different panel sessions were not subjected to statistical analysis; n = 71 and 77, respectively.

and the NaC1/KC1 Cheddar cheeses would be received much better than those similar to the commercial unsalted Cheddar cheese. In addition, it appears appropriate to conclude that cheese similar to the intermediate NaCI/KC1 sample might encounter considerable consumer resistance whereas cheese similar to the low NaC1/KC1 sample probably would be received slightly less well than the low NaC1 sample because of the unfamiliar salty flavor quality of the KC1 salt. Therefore, it is likely that Cheddar cheese acceptable to the consumer can be manufactured successfully with sodium and potassium concentrations more compatible with those recommended by nutritionists (11). The overall high nutritional quality of Cheddar cheese could ease some of the potentially negative impact of the usual amounts of salt in cheese currently marketed, and even modest reductions in sodium then would be highly beneficial. However, a substantial amount of Cheddar cheese is processed into one of the many products available using trisodium citrate and sodium phosphate emulsifying salts (19). The amounts of these salts used approximately doubles the sodium concentration of processed cheeses compared to unprocessed cheeses, and considering increased moisture

contents, the index of nutritional quality of these products becomes less desirable than unprocessed Cheddar cheese by a factor of about three (11). Early manufacturing of processed cheese employed Rochelle salt or sodium-potassium tartrate as an emulsifying agent, but this was abandoned because of problems with unwanted salt crystallizations (19). However, with advances in knowledge about emulsifying systems, it would seem desirable to explore the reinstatement of the use of Rochelle salt emulsifiers as well as investigations of the use of lowered NaC1 and NaC1/KC1 salted cheeses in processed cheeses. ACKNOWLEDGMENTS

The authors express thanks to A. Woo for the F F A analyses. REFERENCES

1 Abernathy, J. D. 1979. Sodium and potassium in high blood pressure. Food Technol. 33(12):57. 2 Anonymous. 1979. FDA estimates sodium and potassium consumption. Food Prod. Devel. 13(1): 26. 3 Anonymous. 1979. Sodium and potassium labeling, Fed. Reg. 44(247):76005. 4 Anonymous. 1980. Page 20 in Toward heaIthful diets. Food and Nutrition Board, Nat. Res. Counc. Nat. Acad. Sci. Washington, DC. Journal of Dairy Science Vol. 65, No. 3, 1982

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