STUDY ON WATERFOWL MEAT TEXTURE – A COMPARISON BETWEEN THE HISTOLOGICAL AND RHEOLOGICAL METHODS

R.M. Radu-Rusu, M.G. Usturoi, Claudia Pânzaru

Abstract
   Among the most used methods in investigating meat structure and texture and its estimated incidence on the sensorial ultimate quality felt by the consumer there is the shear force instrumental measurement using a device with adjustable force and a measurement chamber endorsed with a V gap blade, also known as Warner Bratzler tool. This instrument picks data during sample shearing, in terms of forces necessary to cut the myofibrilar (M force) compound and also the connective compound (C force) of the meat, reported to the elapsed time or distance till total shearing of the sample by the blade. We found out it would be great to compare this instrumental method of muscle toughness estimation with a method belonging to fundamental sciences, using histological and histometrical techniques on the same muscles. The biological material consisted in 20 pieces of breast meat, commercially available as refrigerated duck and goose meat in supermarket (10 samples of duck breast and 10 pieces of goose breast). Out of these material, there were shaped 10 rectangular samples from each breast (10 x 10 = 100 samples per waterfowl species, sized 4 cm length x 1 cm width x 1 cm depth) which were submitted to shear force testing using an Instron type texture analyzer. From the same breast pieces, there were cut 0.5 cm x 0.5 cm x 1 cm samples (5 samples per breast), using the same pattern of muscle fibers orientation like in the previously harvested samples, in order to submit them to paraffin inclusion, microtome cross-section and HEMB coloring, in order to prepare and examine smears using a Motic M230 microscope. Myocytes diameters, cross-section areas were measured and calculated, then reporting to the amount of muscle cell within a 1st order muscle fascicle and to its outer circumference and overall surface, the proportion of pure muscle and connective tissues were derived. The proportions found were compared to those derived from shear forces values readings, knowing the C force instrumentally measured is approx. 0.75-0.9 positively correlated with the connective tissue in muscle. The differences between the instrumental shear force detection of connective tissue and the histological method were quite low and not significantly different. Therefore, it could be stated that the quick instrumental rheological method depicts with accuracy the tissual structure of the muscles, at least at the experimental level we approached.