Food Structure Volume 6 Number 1 Article 6 1987 The Size Distribution and Shape of Curd Granules in Traditional Swiss Hard and Semi-Hard Cheeses M. Ruegg U. Moor Follow this and additional works at: https://digitalcommons.usu.edu/foodmicrostructure Part of the Food Science Commons Recommended Citation Ruegg, M. and Moor, U. (1987) "The Size Distribution and Shape of Curd Granules in Traditional Swiss Hard and Semi-Hard Cheeses," Food Structure: Vol. 6 : No. 1 , Article 6. Available at: https://digitalcommons.usu.edu/foodmicrostructure/vol6/iss1/6 This Article is brought to you for free and open access by the Western Dairy Center at DigitalCommons@USU. It has been accepted for inclusion in Food Structure by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. FOOD MICRO STRU CT URE, Vol. 6 (1987) , pp. 35 - 46 073 0-541 9/87$3 . 00+. 00 Scanni ng Mic roscop y Inte rnational , Chic ag o ( AM F O' Ha re ) , IL 60666 USA THE SIZE DIST RIB UTION AND SHAP E OF CUR D GRANULE S IN TRADIT IO NA L SWISS HARD AND SEMI - HARD CHEESE S M. RU egg and U. Moor Federal Dairy Research Institute 3097 Li ebefel d, Sw i t ze rland Abstract Curd granul e junction patterns in hard The importance of both the size a nd uni­ (Emmenta l er, Gruyere, Sb rinz) and semi-hard form s ize di s tribution of curd granules f or cheeses (Appe nze ll er , Tilsiter, Raclette) wer e cheese quality ha s always been emphasized, in vi sualized on s l ices and examined using light old and mode rn text books on cheese (e . g., microscopy and digital image analysis. Hori­ Steinegger, 1904 ; Fl e i schmann and Weigmann, zontal and vertical sections were cut in diffe­ 1932; Mai r -Wal db urg et al., 1974 ; Scott, rent zones of the loaves, in order to obtain 1981) . The approximate s i ze of the granules i s informati on on the orientati on of the flattened given in the r ec ipe of each cheese variety. It curd gr anul es. depend s on the way in which the coagulum i s c ut The frequency hi stag rams of the c r oss and on the subsequent the rmal and mechanical sec tion areas could in most cases adequately be treatment in the vat and press. Stirr ing and de scribed as a l og -normal distribution~ The heating causes the protein matrix to s hrink and .va1 expe l whey (syneresis). Sy ne resi s continues to ~~~~a~ 31 u~~ ~~~~edm:£o~0 ~ . ~7ar~o :~~5 s~~i -~~~d some extent during pressing. Several studi es cheeses, respectively. assessed the s ignificance of the size of the An e lli ptical form factor was used as a granul es and the curd dust for factors such as measure of the deformation of the granules. The syneresis (Kammerlehner, 1974), eye formation aver age ratio of the e lliptical axes was in the (Clark, 1918; Koestl er , 1933; Hostettler, 1943; range of 0 .41 to 0.56 in horizontal and 0.33 to Schu l z, 1953; Bolliger and Burkhalter, 1g57; 0.48 i n vertical sections. The difference Fll.ieler and Ka ufmann , 1985), cheese yield between the form factors i n the orthogonal (Sc hwarz and Munm, 1951; Bo lliger a nd sec ti ons was 1 es s pronounced i n the Appenze 11 er Burkhal ter, 1957) , moisture, fat con t ent and and Tilsiter cheeses than in the other varie­ ac idification (Koestl e r , 1933; Bo lliger and ties. Significantl y diff erent junction patterns Burkhalter, 1957; Fl uel er and Kaufma nn, 1985) . were observed in regions of the edges and sides The separation of differentl y s i zed particles. of the original billets of curd . The micro­ before pressing and its influence on the qua ­ graphs reveal ed interesting features around the lity of Emmental cheese has been studied by eyes and in the cheese ri nd. Dorner and Ritter (1942) and Bo lliger and Semi - mechanized and traditionally manu­ Burkhalter (1957). Bohac (1970) used frozen factured Appenze 1 1er and Ti 1 s iter cheeses had secti ons to study the orientation of the fl at­ different curd granul e junction patterns, tened curd granules in hard cheese after pres­ ma inly because of di ffer ent moulding and press­ s ing. The grain boundaries in curd and cheese, ; ng arrangements . whi ch are known to have a low fat conte nt (K ing, 19 58 ; Mulder et al., 1966; Han sson et al., 1966), have been studied by va ri ous a uth­ ors and with different techniques i ncl udi ng microscopy of frozen or embedded thin sections Initial paper r eceived Dec ember 12, 1986 (e.g., review by Heinrich, 1968; Fricker and Manuscript received Ma rch 26, 1987 Meyer, 1960), sanded preparations of dehydrated Direct inquiries t o M. W. Ruegg slices (Ka l ab, 19 77; Kalab et al., 1982; Ruegg Telephone numbe r: 41 -31- 598 166 et al., 1985) a nd elec tron mi croscopy (Fricker and Meyer, 1960; Hostettler, 1961; An nibaldi and Nanni , 1979; Ruegg et al., 1980) . Effects of various manufacturing processes and equip­ me nt on junction patterns in chedda r cheese Key words: Cheese, curd granules , light have been i nvesti gated by Emmons et al. ( 1980), m1croscopy, digital image analysis, s i ze Ka lab et al. (1982) and Lowrie e t al. (1982). distributi on, sampl e preparation technique, With very few excepti ons, the work. on s ize mi eros tructu re. 35 M. Ruegg and u. Moor and si ze di s tributi on conducted in the past was Typical di ameters and heights of cheese loaves of a qualitative nature. Very few quantitative were: Emmenta l er 85/20, Gruyere 55/12, Sbrinz data on the sha pe and size of granules after 55/15, Tilsiter 25/7, Appenzeller 33 / 9 and cutting or within the cheese body after pres­ Racl ette 33/7 em. sing are available. Dorner and Ritter (194 2) most probably were the first who s tudied sys­ temati ca lly the size and shape of curd granules throughout loaves of Emmental cheeses . They 3 ' I s took into account the elongation of the curd granules after pressing and measured the diam­ ~ eters on differently oriented cross sections I s {horizontal, vertical, 45° angle). The small (! size of frozen sections and the manual mea sure­ ~ ments permitted the collection of on l y a limi­ I • t ed number of data. Using techniques similar to c--- those introduced by Kalab {1977) and Kalab et al. {1982) together with digital image analy­ zer s. greater s urface areas can be observed an d the acquisition of a large number of data for stereological and statistical analyses becomes possible {Ruegg et al., 1985). In the present work, the size-distribu­ tion. shape and orientation of curd granul es i n some important Swiss hard- and semi-har d type cheeses were examined by means of light micros­ copy and digital image analyses. The primary aim wa s t o obtain reference data for normal first quality cheeses and to inves tigate the extent to which these were affected by differ­ ent manufacturing equipment. The micrographs Fig. 1. Schematic drawing of cheese showing the also revealed useful information about the fine sampling zones for vertical (1 to 6) and hori­ s tructure around the eyes and in the cheese zontal (7 to 12) sections. rind. Materials and Methods Cheese samples Mature Emmenta l er, Gruyere, Sbrinz, Appen­ zell e r, Tilsiter and Raclette cheeses were obtai ned directly from different Swi ss f actor­ ies. Raclette cheese was produc ed from pasteur­ ized milk . Th e other cheese varieties were manufactured traditionally from raw milk ac­ cording to procedures de sc ribed in various textbook s {Mugg li et al., 1959 , Peter and Zollikofer, 1966, Mair-Waldburg et al., 1g74 , Steffen et al., 1987) . The size di stribution of the freshly cut curd particles was as described in s tandard recipes and varied between approxi­ ma tely the s ize of hazelnuts (4 - 8) mm and wheat grains (2-4 mm; e.g., Mair-Waldburg et Fig. 2. Samp ling zone s for semi-hard cheeses in al . , 1974). Loaves of each variety were pur­ the region of the former edge {e l and side { s l chased from 5 to 8 different manufacturers and part of the billets of curd. sampl es were taken from the outer and central zone as indicated in Fig. 1. Vertical (nr. 1 to 6 ) and horizontal sections (nr. 7 to 12} were cut to obtain information about the orien­ Preparation of specimens and microscopy tation of the curd granules inside the cheese A procedure s 1m1i a r to that propo sed by body . The curds of Appenzeller, Tilsiter and Ka lab et al. (1982) wa s used. The horizontal Ra cl et te cheeses were prepressed i n rectangular and vertical sec ti ons , 35 x 25 x 2 IMl, were block s before filling into the r egular round fixed, stained, dehydrated and defatted suc­ hoops . Sections were therefore taken in these cessively with the foll owing soluti ons and cheeses in the region of the original edge and solvents: side part of the billets of curd as shown in - %~utara l dehyde/acrolein {6%, 3%), 2-4 d at Fig.