Texture Assessment of French Cheeses K.D

JFS: Sensory and Nutritive Qualities of Food

Texture Assessment of French Cheeses K.D. ANTONIOU, D. PETRIDIS, S. RAPHAELIDES, Z. BEN OMAR AND R. KESTELOOT

ABSTRACT: The texture of a variety of French cheeses was studied by examining their compositional and mechanical parameters. The data obtained were correlated to those derived from a panel assessment of the sensory textural attributes of the samples. Statistical treatment of the results employing cluster analysis, analysis of variance, and redundancy analysis revealed that the most influential objective variables to characterize the cheese texture are the dry matter content and the resistance to force compression at 10% deformation of the initial sample height. These variables were highly correlated with sensory attributes such as hardness, brittleness, cohesiveness, and adhesiveness. Key Words: cheese texture, French cheeses, sensory evaluation, cheese rheology, cheese characterization

Introduction sponse. A selection of traditional French G3 are Emmental, Beaufort, Pyrenees EXTURE IS ONE OF THE MOST IMPOR- cheeses was used as testing material. Brebis, and Comte Vieux. Ttant quality parameters that deter- Since, the textural characteristics of To investigate which variables affect the mines the identity of a cheese and greatly French cheeses cover a broad spectrum of classification of the cheeses and in what affects its consumer preference. The rela- properties, it was thought that it would be manner, an one-way analysis of variance tionship of textural attributes of cheeses ideal to use the selected cheeses as suit- was conducted. It can be seen (Table 1) with manufacturing and compositional able case studies for texture examination. that the pronounced differentiation of the parameters has been studied for a range group G3 cheeses in relation to the other of cheese varieties, such as Cheddar Results and Discussion groups is due to their greater values of the (Creamer and Olson 1982), Cheddar and DM content and the parameters FF and FR Cheshire (Green and others 1985), Appen- Classification of the cheeses (G3 > G1 > G2) as well as FB, FH, HARD, and zell, Emmental, Tilsit, and Gruyere (Eber- Considering the mean values per COHE (G3 > G1 = G2). The G3 cheeses with hard 1985), La Serena (Fernandez Del cheese sample from all variables exam- DM content > 65% belong to the category of Pozo and others 1988), Camembert and ined, cluster analysis revealed that the hard cheeses. Thus, it is obvious that val- Saint-Paulin (Kfoury and others 1989), cheese varieties could be classified into 2 ues of sensory and instrumental variables buffalo milk Cheddar (Patel and others distinct clusters, one of which can be final- assumed to be related with hardness and 1993), Teleme (Raphaelides and others ly divided into 2 groups making up in total consistency are statistically significantly 1995), Parmigiano Reggiano (Noel and 3 groups (Fig. 1). The cheese varieties that greater than those of the other 2 groups. others 1996) and Cheddar-like goat fall into these 3 groups are as follows: Group G2 cheeses belong to the mold-rip- cheese (Attaie and others 1996). group G1 are Mûnster, Valencay, Tomme ened varieties with a DM content ranging Several attempts have been made to de Savoie, Fourme de Salers, Roquefort, from 41% to 53%. They especially differen- correlate objective measurements with and Bleu d’Auvergne; Group G2 are Cam- tiate from the other groups in relation to sensory textural attributes for a wide vari- embert, Pont l’ Eveque, Reblochon, Saint pH value (G2 > G3 = G1), REC (G3 = G1 > ety of cheeses. Most of the studies em- Nectaire, and Brie de Meaux; and Group G2), instrumental adhesiveness (G2 > G1 = ployed the measurement of mechanical parameters derived from the develop- ment of the General Foods Texture Profile Analysis (TPA) technique (Szczesniak 1966). Some of these studies reported that high (Lee and others 1978) or satisfactory (Chen and others 1979) correlations were achieved for a number of mechanical parameters and sensory attributes. Other studies (Green and others 1985; Jack and others 1993; Raphaelides and others 1995) reported, however, that very poor correlations were obtained for any mechanical and sensory parameter examined using

Sensory and Nutritive Qualities of Food the TPA technique for the types of cheeses they examined. The present study was initiated to investigate whether it is possible to define certain mechanical parameters, measured by a texturometer, that could be reliably Fig. 1—Dendrogram of French cheese varieties clustering showing the arrangement of the related to sensory textural and chemical samples according to the combined effect of chemical, mechanical and sensory variables. attributes of cheeses. This might be help- Abbreviations of cheese varieties : (MUN) Mûnster, (EMM) Emmental, (ROQ) Roquefort, (BEA) Beaufort, (CAM) Camembert, (REB) Reblochon, (PLE) Pont l’ Eveque, (BDM) Brie de Meaux, ful to cheese manufacturers to satisfy (TDS) Tomme de Savoie, (VAL) Valencay, (SAN) Saint Nectaire, (PYB) Pyrenees Brebis, (BDA) quality control and predict consumer re- Bleu d’Auvergne, (COV) Comte Vieux, (FDS) Fourme de Salers.

168 JOURNAL OF FOOD SCIENCE—Vol. 65, No. 1, 2000 © 2000 Institute of Food Technologists G3) and sensory adhesiveness (G2 > G1 > Table 1—Mean values and ranges of chemical, mechanical, and sensory variables between groups of cheeses (G1, G2, G3) as defined by cluster analysis and one-way analysis of G3). The high pH value and the softening variance: p-values of significance and SNK-test comparisons of the cheese texture are characteristics of the mold-ripened cheeses. In mold-rip- Group 1(G1) Group 2 (G2) Group 3 (G3) ened cheeses, lactic acid produced by Min Mean Max Min Mean Max Min Mean Max starters is utilized by molds and yeasts. Chemical variables p Comparisons Lactic acid breakdown leads to neutraliza- DM (%) 48.98 54.75 60.98 41.21 48.57 53.12 64.97 65.53 66.05 <0.001 G3>G1>G2 tion of the curd. For instance, the surface of FAT/DM (%) 45.17 54.57 61.68 46.63 49.89 52.88 48.29 50.17 52.23 0.176 ns TN/DM (%) 5.59 6.04 6.95 5.72 6.70 7.63 5.09 5.92 6.90 0.212 ns a traditional Camembert reaches a pH val- BC (%)a 3.68 6.45 8.16 3.66 4.31 5.21 2.66 4.63 6.34 0.087 ns ue about 7.0 at the end of the ripening pro- PH 5.12 5.78 6.93 6.12 7.03 7.60 5.54 5.87 6.68 0.015 G2>G3 = G1 cess, whereas the pH at the center is Mechanical variables FF (N) 1.85 6.76 14.40 0.15 0.63 1.15 22.20 27.60 32.50 <0.001 G3>G1>G2 around 6.0 (Gripon 1987). The curd of FR (N) 0.98 4.39 9.89 0.02 0.30 0.66 15.70 19.51 23.60 <0.001 G3>G1>G2 Camembert, which is firm and brittle at the FB (N) 2.44 12.62 34.00 0.00 0.98 3.53 33.80 52.43 74.50 <0.001 G3>G1 = G2 beginning of ripening, later becomes soft. FH (N) 6.96 25.92 53.80 6.10 15.06 27.80 50.90 95.20 177.30 0.005 G3>G1 = G2 REC 0.48 0.61 0.70 0.16 0.40 0.57 0.68 0.71 0.72 0.003 G3 = G1>G2 The softening could, thus, be explained by DEF (%) 22.50 27.23 31.80 0.00 19.48 54.10 24.40 35.75 52.90 0.385 ns two processes: (1) as1- casein breakdown by COH 0.05 0.07 0.13 0.14 0.28 0.69 0.05 0.08 0.09 0.057 ns rennet and (2) a rise in pH caused by the GUM (N) 0.35 1.76 2.80 0.85 3.72 6.40 2.50 5.68 7.70 0.026 ns ADH (cm2) 0.00 1.11 1.80 1.69 2.67 3.76 0.00 0.00 0.00 0.001 G2>G1 = G3 surface flora (Gripon 1987). The high adhe- Sensory variables(cm)b siveness of the G2 group is attributed to HARD 2.45 6.46 10.92 2.36 3.81 5.54 9.59 11.33 13.44 0.001 G3>G1 = G2 the pronounced proteolysis of the mold- ELAS 2.65 3.84 5.04 6.29 7.73 9.30 2.99 7.49 13.75 0.045 ns ripened cheeses. The group G1 cheeses FRAC 8.26 9.74 11.05 1.49 4.12 6.65 2.70 6.73 9.44 0.002 G1>G3 = G2 COHE 0.33 4.91 7.78 5.91 6.80 8.12 8.66 10.11 13.08 0.006 G3>G2 = G1 differentiate from those of the other 2 ADHE 4.09 7.66 11.63 11.23 12.36 14.70 0.89 3.47 5.18 <0.001 G2>G1>G3 groups not only in DM, FF, FR, and sensory CHEW 1.60 5.42 7.79 6.04 7.42 9.14 7.63 9.21 11.68 0.027 G3...G2...G1 adhesiveness but also in sensory fractura- DM = dry matter. FAT/DM = fat in dry matter. TN/DM = total nitrogen in dry matter. BC = brine concentration. FF = compression force at 10% deformation. FR = recovery force. FB = break force. FH = compression force at 80% bility where G1 > G2 = G3. The DM of this deformation. REC = recovery. DEF = deformation. COH = cohesiveness. GUM = gumminess. ADH - adhesiveness. HARD group ranges from 49% to 61%, which plac- = hardness.ELAS = elasticity. FRAC = fracturability. COHE = cohesiveness. ADHE = adhesiveness. CHEW = chewiness. a[Salt content/(Salt content+moisture content)] × 100 es the group between the other 2 groups. bMean values of distance measured on a 15-cm line, as described in the text. The sensory adhesiveness exhibited by Dotted lines indicate overlapping differences ns= not significant this group is due to the varieties Mûnster, Roquefort, and Bleu d’Auvergne. These 3 Table 2—Correlation matrix between chemical, mechanical, and sensory variables of french cheeses belong to the category of the mold- cheese samples. Correlation coefficients greater than 0.700 are shown (critical values at 0.05 probability level: r =0.514) ripened cheeses; Roquefort and Bleu 0.05,13 d’Auvergne especiallybelong to the blue- DM pH FF FR REC FB FH ADH HARD ELAS COHE veined cheeses that show extensive pro- FF 0.855 teolysis. The brittleness, expressed by frac- FR 0.858 0.999 REC 0.837 -0.842 turability, shown by the G1 group cheeses FB 0.799 0.886 0.893 could be attributed to their high brine con- FH 0.719 0.725 0.935 centration which ranges from 3.7% to 8.2%. COH -0.770 ADH -0.907 -0.778 -0.776 -0.865 -0.734 HARD 0.795 0.871 0.866 0.750 0.895 0.819 -0.807 Multivariate analysis FRAC -0.757 An effort was made to investigate pos- COHE 0.741 0.777 0.761 ADHE -0.860 -0.811 -0.808 -0.852 -0.841 -0.776 0.879 -0.929 sible correlations among the various pa- CHEW 0.862 rameters. Thus, a correlation matrix (Table DM = dry matter. FAT/DM = fat in dry matter. TN/DM = total nitrogen in dry matter. BC = brine concentration. FF = 2) was formed that included the composi- compression force at 10% deformation. FR = recovery force. FB = break force. FH = compression force at 80% deformation. REC = recovery. DEF = deformation. COH = cohesiveness. GUM = gumminess. ADH = adhesiveness. HARD = hardness. tional, instrumental, and sensory vari- ELAS = elasticity. FRAC = fracturability. COHE = sensory cohesiveness. ADHE = sensory adhesiveness. CHEW = chewiness. ables of all samples. As it can be seen, fairly strong correlations in the majority (r > 0.700) were obtained among the FF, FR, sensory adhesiveness showed the oppo- nificant (greater than 2). The variable DM and FB variables. ADH was negatively cor- site behavior. Sensory cohesiveness was produced the highest value of interset correlated to FF, FR, FB, and REC as it should positively correlated with FB, FH, and sen- relation for axis 1 (0.866) and both pH and have been expected since REC could be sory hardness, which could be expected BC for axis 2 although with loose value (- considered as representing elasticity since the panelists perceived the firmness 0.641 and 0.632 respectively). whereas ADH represents plasticity in the of the texture of the sample just before it The overall dependent (sensory and rheological sense. was ruptured during biting. mechanical) and explanatory (chemical) Between, mechanical, and composi- Three criteria of variable importance variable relation explained 95% of the total tional variables, the DM was highly corre- were employed for the redundancy analy- variation regarding the first 2 major axes. lated with FF, REC, and FB as it should sis, namely, forward selection of variables, Sensory and mechanical variables alone have been expected since the high dry t-values of the canonical coefficients, and explained 70.2% of the total variation. matter content signifies the presence of a interset correlation coefficients with axes 1 Fig. 2 gives a global view of the effect of more compact network structure while the and 2, (Table 3, Ter Braak 1988). The step- all variables both dependent and explan- plasticizing effect of the water is less for wise forward procedure revealed the dry atory on the 15 cheese samples based on low water content. matter as the most important variable in the results of the redundancy analysis. Sensory hardness is positively correlat- the analysis followed by pH, BC, and TN/ Variables with longer arrows are more im- ed with FF, FR, FB, FH, REC, and DM and DM. All the above variables are important portant in producing effects while those negatively correlated with ADH, which is for a second reason: the t-values of their with the same direction show positive cor- roughly as expected. On the other hand, canonical coefficients are statistically sig- relation and those with inverse direction

Vol. 65, No. 1, 2000—JOURNAL OF FOOD SCIENCE 169 Sensory and Nutritive Qualities of Food Texture of French Cheeses . . .

2 2 Table 3—Statistics of the redundancy analysis: R and cumulated R values of the forward pattern of 2 subsets of variables. The first selection of variables, t-values of the canonical coefficients, and interset correlations of the chemical variables with axes 1 and 2 subset is represented by HARD and DM, alternated between the mechanical vari- t-values of Canonical coefficients Interset correlations ables FB, FF, and FR (appearing nearly identical) and REC. This variable subset Variable R2 Cum R2 AXIS 1 AXIS 2 AXIS 1 AXIS 2 determines the cheeses COV, BEA,and DM 0.43 0.43 7.232 0.323 0.866 -0.272 PYB and also the TDS variety, which al- FAT/DM 0.01 0.74 -0.035 -1.075 -0.378 -0.554 TN/DM 0.06 0.73 2.141 0.221 -0.174 0.598 though belongs to group G1 according to BC 0.16 0.59 -2.538 -3.232 -0.234 -0.656 the clustering results, is positioned here pH 0.08 0.67 -1.549 3.054 -0.475 0.632 due to its high dry matter content (57.6%) DM = dry matter. FAT/DM = fat in dry matter. TN/DM = total nitrogen in dry matter. BC = brine concentration). in conjunction with its high sensory hardness score and its high values of mechanical parameters related to hardness. It show negative correlation. The intensity of G3 on the lower right quartile. The upper should be noted that this subset of vari- this correlation increases as the angle be- right quartile is occupied by only one ables is also strongly and negatively corre- tween the variables diminishes. Appar- cheese (EMM). lated with the variables of group G2. Em- ently, 2 variables with angle direction of Three bundles of variables with strong mental is uniquely expressed by the sec- 90o are totally not correlated. Samples po- positive correlations appear in the graph. ond subset of variables, CHEW and COHE sitioned close to an arrow of a variable The first bundle consists of 2 pairs of strongly correlated with GUM, and sec- show strong relationship. The cheese sam- strongly correlated variables of different ondarily by ELAS. Emmental possesses a ples are shown to be easily classified ac- approach, pH with COH and ADHE with unique rubber-like texture that clearly cording to their position in the graph into ADH, and these are indicative of G2- distinguishes this variety from all the oth- the 3 groups: G2 on the upper left part of cheeses.The second bundle of the vari- ers examined. This kind of texture is best the graph, G1 on the lower left part, and ables clearly describes the G3-cheeses in a described by the aforesaid sensory variables. Finally, the third bundle of variables, that is FAT/DM, BC, and FRAC represent the group G1 cheeses. These variables are strongly and negatively correlated with ELAS and to a lesser degree with GUM, CHEW, and COHE. From the discussion above, it can be seen that the mechanical variables that are more highly correlated with sensory and chemical variables are the FF and FR, which are actually identical. On the other hand, from all TPA parameters measured, the only one that substantially contrib- utes to the characterization of the varieties is adhesiveness. This is because adhesiveness expresses the stickiness of the sample after the termination of the compression and simulates the same phenome- non occurring in the mouth during mastication of certain French cheeses. These varieties possess the easily perceived property to become sticky to the teeth after biting. However, the importance of this mechanical variable is of limited value since it only helps to differentiate the sticky cheeses from the no-sticky ones. The reason why the 10% compression measurements (i.e., the FF and FR variables) better evaluate the cheese texture than the 80% compression measurements (i.e., FH, FB, etc.) could be attributed to the fact that the panelists, on testing, press the samples in their mouth not only slowly but Sensory and Nutritive Qualities of Food Fig. 2—Biplot based on redundancy analysis of french cheese samples and sensory/physical also cautiously so that they have sufficient profile with respect to 5 chemical variables. The lines for sensory/physical and chemical variables display the approximate correlation coefficients between these 2 sets of variables. time to sense the full magnitude of the re- Abbreviations: (MUN) Mûnster, (EMM) Emmental, (ROQ) Roquefort, (BEA) Beaufort, (CAM) sistance exhibited by the sample prior to Camembert, (REB) Reblochon, (PLE) Pont l’ Eveque, (BDM) Brie de Meaux, (TDS) Tomme de rupture. This action was here imitated by Savoie, (VAL) Valencay, (SAN) Saint Nectaire, (PYB) Pyrenees Brebis, (BDA) Bleu d’Auvergne, (COV) Comte Vieux, (FDS) Fourme de Salers, DM (Dry matter), FAT/DM (Fat in dry matter), TN/ compressing the samples by 10% of their DM (Total nitrogen in dry matter), BC (Brine concentration), FF (Compression force at 10% initial height at a low speed (1cm/min). deformation), FR (Recovery force), FB (Break force), FH(Compression force at 80% deforma- The 10% deformation ensures that only tion), REC (Recovery), DEF (Deformation), COH (Cohesiveness), GUM (Gumminess), ADH (Ad- hesiveness), HARD (Hardness), ELAS (Elasticity), FRAC (Fracturability), COHE (Cohesiveness), limited secondary bonding was destroyed ADHE (Adhesiveness), CHEW (Chewiness). and the structure can be easily recovered

170 JOURNAL OF FOOD SCIENCE—Vol. 65, No. 1, 2000 to a large extent. In the case of 80% defor- ers 1993) was focused solely on the senso- part of the price scale of these instruments mation, most of the primary bonding is ry evaluation of the texture of hard and and not necessarily by a machine such as ruptured, and the fracturing of the struc- semi-hard cheeses. In this study, it was at- Instron. By performing simple compres- ture is not only extensive but also uncon- tempted to define, using trained taste sion measurements, a cheese manufac- trolled. Thus, minor differences that distin- panelists, sensory parameters that might turer can easily, cheaply, and rapidly mon- guish the texture of one variety from the be suitable to characterize the texture of itor the constancy in texture of produce other are easily overlooked. This observa- cheeses. They did not try to relate the de- with a degree of accuracy that is accept- tion was also stated by Walstra and Peleg rived sensory parameters to instrumental able for industrial purposes. (1991). Hence, it can be said that the 10% ones. Thus, this study is of limited practi- compression measurements of the cheese cal value for the cheese manufacturers Conclusion samples are more sensitive than the 80% who are not able and willing to employ a CCORDING TO THE RESULTS OF THE compression measurements. Besides, most number of trained panelists for quality Avarious statistical methods employed, of the TPA parameters were unable to dif- control purposes but are only willing to in- the objective variables that mostly help to ferentiate the cheese varieties as the statis- vest in an instrumental technique that will classify the cheese varieties into groups tical analysis revealed. Walstra and Peleg reliably enable them to control their prod- and to characterize their texture are: pri- (1991) for this reason recommended that ucts fairly rapidly and at a minimum cost. marily, the dry matter content and the in- the use of the TPA attributes for cheese tex- The present study revealed that the strumental parameters FF and FR and, ture analysis be discouraged. texture of cheeses can be determined with secondarily, the pH, FB, FH, recovery, and A collaborative study that was carried fairly reasonable accuracy using instru- adhesiveness. All sensory textural at- out by a group of European dairy institu- mental techniques. These techniques can tributes employed were able to differenti- tions under the auspices of the European be performed by commerciallyavailable ate the cheese samples examined, with Union FLAIR Program (Lavanchy and oth- texturometers that belong to the lower the exception of elasticity and chewiness.

Materials and Methods testing. Also samples were taken from at tween contact surfaces. least 5-mm deep in the cheeses to limit In all series of determinations, the Cheese samples the effects of surface drying (Jack and cross head and the chart speeds of the Fifteen cheese samples, purchased others 1993). Two series of determina- instrument were 10 mm/min and 50 from a cheese specialty shop, were stud- tions were made using separate samples: mm/min respectively. The determina- ied. Thesamples belonged to the follow- (1) Compression at 10% deformation tions were replicated 4 times for each ing cheese varieties: Mûnster (MUN), of the initial sample height. Parameters sample treatment. Emmental (EMM), Roquefort (ROQ), measured were: force at peak height of Beaufort (BEA), Camembert (CAM), Re- 10% compression (FF); recovery force Sensory evaluation blochon (REB), Pont l’ Eveque (PLE), (FR), measured after the sample was re- Sensory testing was carried out using Brie de Meaux (BDM), Tomme de Savoie laxed under constant compression for a an experienced 35-member panel, se- (TDS), Valencay (VAL), Saint Nectaire time period equal to that elapsed for the lected from the department’s staff. The (SAN), Pyrenees Brebis (PYB), Bleu completion of the 10% compression; per- panel’s experience on sensory assess- d’Auvergne (BDA), Comte Vieux (COV), centage recovery (REC) to the initial ment was acquired through training, us- Fourme de Salers (FDS). height of the compressed sample at the ing the methodology suggested by the point of the FR measurement. French Standards Association (AFNOR Composition (2) Compression at 80% deformation 1990) for sensory analysis as well as The chemical analysis of the cheese of the sample. Each sample was com- through their regular participation, for at samples was carried out employing the pressed axially in 2 consecutive com- least 3 to 4 years, in similar kinds of following methods: dry matter content pression cycles («two bites» according to projects concerning cheeses, meat prod- by the gravimetric method of Mumm TPA technique). Parameters measured ucts, processed fruits, etc. and others (1970); salt content by the were: force recorded at the first signifi- The technique used for the sensory method of Schneider and Roeder (1979); cant break of the sample and designated assessment was that of the unstructured fat content by the method of Gerber and as FB (represents TPA-brittleness); per- scaling: The panelists were asked to nitrogen content by the Kjeldahl method centage deformation of the compressed taste the samples in 6 runs, i.e., the same (Kirk and Sawyer 1991). sample at the point of the first signifi- samples allocated to each panelist wer- cant break, designated as DEF; peak etested by him/her 6 times (runs). In Texture measurements force during first compression cycle, des- each run, a separate attribute was as- Textural properties were measured ignated as FH (TPA- hardness); cohe- sessed, i.e., hardness (HARD), elasticity with an Instron Universal Testing Ma- siveness or the ratio of positive area dur- (ELAS), fracturability (FRAC), cohesive- chine, Table model 1140 (Instron Ltd, ing second compression cycle to that ness (COHE), adhesiveness (ADHE), High Wycombe, Bucks, U.K.), operating in during the first compression, designated and chewiness (CHEW). For each run, a the compression mode. Cylindrical sam- as COH; gumminess or the product of FH reference was employed that was arbi- ples were prepared from each cheese and COH, designated as GUM; adhe- trarily chosen, after a series of prelimi- block, using a metal borer of the same in- siveness or the negative force area dur- nary tests were conducted, to represent ner diameter as the diameter of the sam- ing the first «bite», designated as ADH. the mean level of the attribute of con- ples. Test piece dimensions were 21 mm The measurements were carried out cern. All references were samples of a both in diameter and height. Samples using a 36-mm dia flat plate probe as French cheese variety (Mont des Cats) were cut at 4 °C and left at room tempera- compression attachment lubricated with that was not one of the cheeses exam- ture (20 °C) for at least 30 min prior to vegetable oil to overcome friction be- ined. A balanced incomplete block de-

Vol. 65, No. 1, 2000—JOURNAL OF FOOD SCIENCE 171 Sensory and Nutritive Qualities of Food Texture of French Cheeses . . .

sign was used, and each panelist as- erence was marked as M at the center of (1987) and performed by the CANOCO sessed 3 samples and the reference that the line. statistical software (Ter Braak 1988). One was in the form of dice, with dimensions of the attractive features of redundancy of 2 cm. The samples were taken out Statistical analysis analysis is that it leads to an ordination from refrigeration (4 °C) 30 min prior to The 35 panelists examined 3 samples diagram that simultaneously displays (1) their testing and left for equilibration at (the reference not included), according the main pattern of the variation of the room temperature. to the scheme: t = 15 samples, k = 3 sam- dependent variable set as far as this vari- The judgement of the attributes was ples per panelist, b = 35 panelists, r = 7 ation can be adequately explained by the made as follows. Hardness was deter- replicates per cheese sample, i.e., 7 independent set and (2) the main pat- mined by biting a sample dice using the judgements per sample, ␭ = 1 similar pair tern in the correlation coefficients be- molar teeth. The greater the effort the of samples appearing in the same panel- tween the dependent variables and ea- panelists made to completely penetrate ist (Cochran and Cox 1957). This bal- chof the independent variables. In sim- the sample the firmer the sample was. anced incomplete block analysis that ple terms, the redundancy analysis is a The degree of bouncing of the sample be- performs as a two-way analysis of vari- combined two-step approach to relate a tween two successive bitings indicated ance (ANOVA; samples and panelists), dependent set of variables to an inde- the magnitude of elasticity. The fractura- provided adjusted means of the sensory pendent set. First, a few ordinations axes bility was assessed by the degree of brit- variables for each cheese sample. that summarize the overall variation be- tleness shown by the sample at the first Cluster analysis on samples was per- tween the dependent variables are ex- biting. The cohesiveness was judged formed to detect potential groups (clus- tracted. Second, weighted sums of the in- from the perceived degree of consistency ters) with distinct textural characteristics dependent variables are calculated in that the sample possessed during biting. that could classify the cheeses into cate- such a way that most closely fit each of Adhesiveness was judged by the sticki- gories. The mean values per cheese sam- these ordination axes. The principal axes ness of the sample in the mouth through- ple from all variables examined (chemi- are constrained to be linear combinations out mastication, and chewiness was cal, mechanical, and sensory) were com- of the independent variables. In fact, this judged by the energy required to masti- bined to clusters, following the Ward’s analysis is a Principal Component Analy- cate the sample to a state ready for swal- method of clustering, using the Pearson’s sis of several Y variables with respect to lowing. The panelists recorded their eval- measure of distance for the sample data several X variables under the condition uation by drawing a vertical line for each (Lance and Williams 1967). The formed that the first major component of the de- sample across a horizontal line 15-cm groups were examined using one-way pendent set and the first major compo- long at the point that best reflected their ANOVA to statistically establish what dif- nent of the independent set must give a perception of the magnitude of that at- ferent characteristics they share. Multiple correlation maximum. The next two major tribute. The left end (0 cm) of the line was comparisons between the means of the components of both variable sets must marked for the hardness as very soft, for sample groups for each variable was per- also give a correlation maximum, less the elasticity as not elastic, for the fractur- formed following the Student-Newman- powerful, and so on. It differs from the ability as not brittle, for the cohesiveness Keuls test procedure (Zar 1984). factor analysis mainly in that the canoni- as not cohesive, for the adhesiveness as To elucidate the effects of the compo- cal coefficients (weights) pertain to the not sticky, and for the chewiness as easy sitional data as independent variables on unique contribution of the respective to masticate. The right end (15 cm) was both mechanical and sensory characteris- variables with a particular canonical axis; marked respectively, as very hard, very tics taken as the dependent variables of the factor loading in factor analysis repre- elastic, very brittle, very cohesive, very the cheese samples, a redundancy analy- sent the overall correlations of the respec- sticky, and difficult to masticate. The ref- sis was used as described by Ter Braak tive variables with the canonical axis.

References Ter Braak CJF. 1987. Unimodal models to relate species to lin. Lait 69:137-149. environment. Agricultural Mathematics Group. Wagenin- AFNOR. 1990. Norme Francaise. Analyse Sensorielle. Meth- Kirk RS, Sawyer R.1991. Pearson’s Composition and Analysis gen, Netherlands: Ministry of Agriculture and Fisheries, th odologie. NF V 09-021.Tour europe cedex 7 92049. Paris: of Foods. 9 ed. London: Longman Scientific and Tech- Box 100, NL-6700 AC. p 110-111, 128-129. A.F.N.O.R. p 1-28. nical. p 9-11, 479. Ter Braak CJF. (1988). CANOCO: A FORTRAN program for Attaie R, Richter RL, Risch E. 1996. Manufacturing parame- Lance GN, Williams WT. 1967. A general theory of classifica- canonical community ordination by partial detrended and ters and rheological characteristics of Cheddar-like hard tory sorting strategies. I. Hierarchical systems. Computer canonical correspondence analysis, principal component goat cheese. J. Dairy Sci. 79:1-7. Journal 9:373-380. analysis and redundancy analysis. Agricultural Mathemat- Chen AH, Larkin JW, Clark CJ, Irwin WE. 1979. Textural anal- Lavanchy P, Berodier F, Zannoni M, Noel Y, Adamo C, Squella ics Group. Wageningen, Netherlands: Ministry of Agricul- ysis of cheese. J Dairy Sci. 62:901-907. J, Herrero L.1993. L’ evaluation sensorielle de la texture des ture and Fisheries Box 100, NL-6700 AC. p 47-50. Creamer LK, Olson NF. 1982. Rheological evaluation of ma- fromages a pate dure ou semi-dure. Etude Interlabora- Walstra P, Peleg M. 1991. General Considerations. In: Rheo- turing Cheddar cheese. J. Food Sci. 47:631-646. toires. Lebensmit.-Wiss. u. –Technol. 26:59-68. logical and Fracture Properties of Cheese. Bulletin of the nd Cochran WG, Cox GM. 1957. Experimental Designs. 2 ed. Lee C-H, Imoto EM, Rha C. 1978. Evaluation of cheese tex- International Dairy Federation No 268. p 3-4. Brussels, Chichester, U.K.: John Wiley and Sons. 478 p. ture. J. Food Sci. 43:1600-1605. Belgium: I.D.F. Eberhard PP. 1985. Rheologische eigenschaften ausgewahl- Mumm H, Kynast S, Gussek KW, Kellermann R, Konra DH, Zar, J.H. 1984. Biostatistical analysis. 2nd ed. London: Pren- ter kasesorten [doctoral dissertation]. Technischen Hoch- Keller W. 1970. Methoden Bd. VI: Untersuchung von Milch, tice Hall. p 190-191. schule Zurich, Switzerland. Milcherzeugnissen und Molkereihiffstoffen, 3, Aufl. Ger- JFS 19990214 received 2/18/99; revised 9/23/99; accepted12/ Fernantez del Pozo B, Gaya P, Medina M, Rodriguez-Marin many: Neumann Verlag. p 25-30. 2/99. A, Nunez M.1988. Changes in chemical and rheological Noel Y, Zannoni M, Hunter EA. 1996. Texture of Parmigiano characteristics of La Serena ewes’ milk cheese during rip- Reggiano cheese: Statisticalrelationships between rheo-

Sensory and Nutritive Qualities of Food The technical assistance of Sandra Mercier and Lydie Vitse ening. J. Dairy Res. 55:457-464. logical and sensory variates. Lait 76:243–254. during the preparation and the analysis of the samples is Green ML, Marshall RJ, Brooker BE. 1985. Instrumental and Patel HG, Upadhyay KG, Miyani RV, Pandya AJ. 1993. In- greatly appreciated. sensory texture assessment and fracture mechanisms of stron texture profile of buffalo milk Cheddar cheese as Cheddar and Cheshire cheeses. J.Texture Stud. 16:351-364. influenced by composition and ripening changes. Food Authors Antoniou, Petridis and Raphaelides are Gripon JC. 1987. Mould-ripened cheeses. In: Fox PF, editor. Quality Pref. 4:187-192. affiliated with the Department of Food Technol- Cheeses: Chemistry, Physics and Microbiology. Vol 2. U.K.: Raphaelides S, Antoniou KD, Petridis D.1995 Texture evalu- ogy, T.E.I. of Thessaloniki, P.O.Box 14561, 54101 Elsevier Applied Science. p 121-149. ation of ultrafiltered Teleme cheese. J. Food Sci. 60:1211- Jack FR, Paterson A, Piggot JR.1993. Relationships between 1215. Thessaloniki, Greece. Authors Omar and rheology and composition of Cheddar cheeses and tex- Schneider K, Roeder H. 1979. Die Praktische Milchprufung Kesteloot are affiliated with ISA, Universite ture as perceived by consumers. Int. J. Food Sci. Technol. und die Kontrolle von Molkereiprodukten, Wyss Erben, Catholique de Lille, 41 rue du Port, 59046 LILLE 28:293-302. Bern. CEDEX, France. Direct inquiries to author Kfoury M, Mpagana M, Hardy J. 1989. Influence de l’affinage Szczesniak, A.S. 1966. Texture measurements. Food Technol. Raphaelides (E-mail: [email protected]). sur le proprietes rheologiques du camembert et saint pau- 20:52-58.

172 JOURNAL OF FOOD SCIENCE—Vol. 65, No. 1, 2000