Introduction. Material and methods

Transcription

1 Milk quality and cheese yield of four European and African goat biotypes bred in a semi arid area of Argentina Northwest Victor Herrera *, Mónica Chavez 1, María F. Gonzáles 2, Javier M. Quinteros 2, Marcela E. Ogas 2 and Roxana Páez 3 Introduction Cheese is the most important commercial product obtained from goat milk. One reason may be that this product allowed extending shelf life of milk. other is that cheese has sensorial attraction: a wide variety of textures and flavors are available. Many factors are linked to cheese quality and yield, among them milk quality is an important one (Boyazoglu and Morand-Fehr. 2001). Milk quality of different goat biotypes is studied to understand and to improve its contribution to cheese quality and yield (Verdier-Metz et al. 2001; Oliszewski et al. 2002; Gou et al. 2004; Fekadu et al. 2005; Chavez et al. 2006). Saanen, Anglo-Nubian, Toggenburg and Alpine goat biotypes had European and African origin and they had been introduced in Argentina during 80 s from Australia and New Zealand. However, there are little information published about milk quality and cheese yields from these different biotypes after a period of adaptation in Argentina. The objectives of the present work were to evaluate and to compare milk and cheese quality parameters and cheese yields of Saanen, Anglo-Nubian, Toggenburg and Alpine biotypes bred together at similar feed and management conditions in semi-arid area of Northwest of Argentina (NWA). Goat from the four referred biotypes were bred at Catamarca province (NWA), located at 568 m over the sea. Material and methods Bulk milk samples and milk used to cheese manufacture came from animals in good health conditions from the dairy goat farm of the Instituto Nacional de Tecnología Agropecuaria (INTA) of Catamarca (average annual rain recording 403mm; average temperature 20.7ºC). Saanen (S), Anglo-Nubian (A-N), Alpine (A) and Toggenburg (T) herds were in their 5 th month of lactation during experiment and were formed by 15, 11, 12 and 15 animals respectively. They were fed in alfalfa field (Medicago sativa) and supplemented with 700g/day of corn grain (60%) and alfalfa hay (40%). Trail consisted of milking animals once a day, collecting bulk milk samples for analysis and elaborating cheese with the same procedure (INTA Protocol PP 1/09. pressed uncooked cheese with Streptococcus thermophilus, 1.5% and Lactobacillus plantarum ETC17, 0.3% as starter cultures provided * Instituto Nacional de Tecnología Agropecuaria- Catamarca vgherrera@correo.inta.gov.ar, Instituto Nacional de Tecnología Agropecuaria de Salta 1 ; de Catamarca 2 y de Rafaela 3.

2 by CERELA-CONICET). Trail was applied to every biotype during the same journey and repeated in two other days within the week. Milk analyses were: gross composition (%, w/w total solid, protein, fat and ash) by ultrasonic method (Lactostar); nitrogen profile (micro- Kjeldalh) and 6.38 was the parameter used to calculate true protein, casein and whey protein. Cheese yield (kg of cheese per 100 l of milk) was measured after 12h of elaboration and before brining. Cheese yields were adjusted to moisture content to calculus according to Gou et al. (2004) formula (MY i = Yield i *average moisture/moisture i ). Cheese quality parameters were measured when cheeses were fresh: humidity (%, gravimetric method with halogenous balance); salt (%, IRAM ); protein (%, Kjeidahl FIL-IDF, 1993); fat (%, IRAM 14003) and ph (Bradley et al, 1993). Descriptive statistics, ANOVA and correlation analysis were performed using Infostat program (2009) and α= Results and discussion Average and standard deviation of milk quality parameters of every goat biotype are shown in Table 1 and Table 2. Results were in agreement to previous data (Morgan et al. 2003; Soryal et al. 2004; Gou et al. 2004). It was important to note that biotype Anglo-Nubian presented higher value of protein than the one expected. Chavez et al. (2006) and Scaltritti and Chavez (2009) reported 4.09±0.21 and 3.91±0.18% of Anglo-Nubian protein concentration respectively in herds of the region. However, high protein values may occur because of genetic resource. On the other hand, Saanen and Alpine biotypes presented milk fat values lower than those reported (3.94±0.18 and 4.13±0.27% respectively) by Scaltritti and Chavez (2009) from herd of the same region; low fat values may be connected to animal diet. Saanen and Toggenburg biotypes showed the lowest no protein nitrogen. This may indicate that these biotypes had better response to nutritional aspect; however further studied should be done on the subject. Table 1: Mean values of milk quality parameters and standard deviation according to goat biotype Biotype Fat (%) Protein (%) Ash (%) Total solids (%) A- N 4.40 ±0.54 b 4.53 ±0.25 b 0.89 ±0.04 a ±1.11 b S 2.98 ±0.14 a 3.18 ±0.19 a 0.96 ±0.01 ab ±0.24 ab A 2.66 ±0.29 a 3.12 ±0.09 a 0.98 ±.04 b ± 0.42 a T 3.12 ±0.27 a 3.03 ±0.08 a 0.96 ±0.01 ab ±0.32 ab Table 2: Protein profile and no protein nitrogen content according to goat biotype Biotype True protein (%) Casein (%) casein/ True Prot.*100 Whey protein (%) No protein nitrogen (%) A-N 4.40±0.25 b 3.43±0.18 b ±0.09 a ±6e -4 b S 3.06±0.19 a 2.30±0.24 a ±0.08 a ±6e -4 a A 2.98±0.10 a 2.10±0.18 a ±0.11 a ±1e -3 b T 2.91±0.08 a 2.14±0.08 a ±0.07 a ±6e -4 ab

3 Results showed that Anglo-Nubian biotype presented the highest content of fat, protein, total solids in milk and also casein concentrations, which were important to cheese structure and yields. On the contrary, this biotype presented minor value of ash. This biotype had also the highest relation value between casein and true protein, suggesting that Anglo-Nubian had the greatest proportion of casein among studied biotype. This was in agreement to cheese yield which was the highest (Table 3). On the other hand, Saanen, Alpine and Toggenburg biotypes presented equal values of fat casein and total solids in milk and, so were cheese yields. Although Alpine showed the lowest value to the relationship between casein and true protein, yields was the same as the ones presented by Saanen and Toggenburg; probably mineral content may contribute to this. Table 3: Cheese yield and quality parameters according to goat biotype Biotype Yield Moisture Fat (%) Protein Salt (%) ph (kg/100 l) (%) (%) A-N 17.38±1.87b 53.37±1.35a 23.33±0.52b 19.10±0.96a 1.08±0.08a 5.08±0.08a S 12.57±0.55a 55.06±1.80a 20.40±0.35a 19.60±0.72a 0.88±0.10a 5.24±0.04a A 12.67±0.91ª 54.00±1.02a 21.00±0.50a 19.96±0.59a 0.86±0.08a 5.14±0.12a T 12.87±0.68a 52.79±0.97a 24.43±1.25b 19.18±0.53a 0.85±0.12a 4.98±0.15a Cheese yields obtained were in agreement to previous works. Soryal et al.(2004) reported cheese yield of Domiati cheese between 12 to 18% and Olizsewski et al. (2002) found 16.5% as mean yield value to cheese made of Criollo biotype milk. It should be mentioned that moisture content of soft cheese depended on cheese manufacturing technology; in effect Domiati cheese average moisture may be 60% (Gou et al. 2004) and moisture of Cacioricotta cheese was ranged between 48.7 and 57.1% (Albenzio et al. 2006). Chavez and McSweeney (2009) reported values of moisture, fat and protein to soft cheese of Saanen biotype milk in the northwest region of Argentina similar to those found in the present work. Values of salt were lower than those obtained by these authors ( %) and those mentioned ( %) by Albenzio et al. (2005). This variable depended on used cheese technology, also did ph. Cheese protein content of Anglo-Nubian milk was expected to be the highest value; suggesting that part of it was lost during processing. On the other hand, a good fat retention was obtained when Toggenburg milk was processed; showing that cheese technology was suitable to this milk quality biotype. The relation between moisture-adjusted cheese yield (MY) and milk composition parameters was explored. Average moisture value considered was 53.8%. Results showed that MY had correlations with casein (r=0.899), protein (r=0.895), protein plus fat (r=0.890), fat (r=0.845) and total solid (0.785). All thought casein content was the most relevant milk composition parameter to cheese yield, protein and eq.(1). were proposed to calculus since this variable was simple to measure. MY (%) = 3.22* P R 2 = 0.80 (1)

4 Conclusion The four biotypes analyzed presented good milk parameters values; however Anglo-Nubian showed the best cheese yield. Cheese yield of Saanen, Alpine and Toggenburg were the same. Studies on cheese technology to Anglo-Nubian milk should be considered in further work. References Albenzio M; Caroprese R; Marino A; Miscio A; Santillo A; Sevi A (2006) Small Ruminant Research 64: Boyazoglu J. and Morand-Fehr P. (2001) Small Ruminant Research 40:1-11. Bradley, R. L., E. Arnold, D. M. Barbano, R. G. Semerad, D. E. Smith, and B. K. Vines Chemical and physical methods in Standard methods for the examination of Dairy Products Chavez M and McSweeney P.L.H. (2009) Food Science and Technology International Annual Meeting of Córdoba. CD Vol.1 GP1:28 Chavez M; Orosco S;Torres N; Rodriguez T and Candotti J. (2006) Food Science and Technology International Annual Meeting of Córdoba. Vol. 1 P365:391. Fekadu B; Soryal K; Zeng S; Van Hekken D; Bah B and Villaquiran M. (2005) Small Ruminant Research 59: Gou M; Park Y; Dixon P; Gilmore J and Kindstedt P. (2004) Small Ruminant Research 52: Olizsewski R; Rabasa A; Fernandez J; Poli M and Nuñez M. (2002) Zootecnia Tropical 20(2): Morgan F; Massouras T; Barbosa M; Roseiro L; Ravasco F; Kandarakis I; Bonnin V; Fistakoris M; Anifantakis E; Jaubert G and Raynal-Ljutovac K (2003) Small Ruminant Research 47:39-49 Scaltritti R. and Chavez M. (2009) Food Science and Technology International Annual Meeting of Córdoba. CDVol.1 GP51:122 Soryal K; Zeng S; Min B; Hart S; Beyene F (2004) Small Ruminant Research 54: Verdier-Metz I; Coulon J and Pradel P. (2001) Anim. Res. 50: Publicado en Proceeding of 10th International conference of Goats (ISBN ). Area 02, Nº99-1, pag

5