Journal of Dairy Research

Research Article

Effects of different storage conditions, the farm and the stage of lactation on renneting parameters of goat milk investigated using the Formagraph method

Michele Pazzolaa1 c1, Filippo Baliaa1, Maria Luisa Dettoria1, Maria Consuelo Muraa1, Vincenzo Carcangiua1 and Giuseppe Massimo Vaccaa1

a1 Department of Animal Biology, University of Sassari, via Vienna 2, 07100 Sassari Italy

Abstract

This study evaluated the effect of storage on renneting properties of goat milk investigated using the Formagraph method. Milk samples from 169 goats in three farms (F1, F2 and F3) were analysed during an entire lactation (45, 75, 105, 135 and 165 days in milking DIM), to obtain renneting parameters, both from fresh milk and after storage with Bronopol and freezing at −20°C and −80°C. As regards fresh milk, mean values of clotting time were between 12·51 (45 DIM) and 13·29 min (105 DIM and F2), the curd firming time between 1·77 (45 DIM) and 2·15 min (F1) and curd firmness between 42·09 (165 DIM) and 49·55 mm (45 DIM). No statistical difference was recorded after storage. After regression analysis, all prediction models showed significance value at P<0·001 with the highest R2 value for clotting time, 0·710 (fresh vs. frozen milk at −20°C), and the lowest for clot firmness, 0·281 (fresh vs. frozen milk at −80°C). Results demonstrated that assessment of goat milk coagulation properties using the Formagraph method is also achievable after freezing or Bronopol addition.

(Received January 14 2011)

(Accepted May 08 2011)

(Online publication July 21 2011)

Correspondence:

c1 For correspondence; e-mail: pazzola@uniss.it