Published in Scientific Papers. Series D. Animal Science, Vol. LXIII, Issue 2
Written by Răzvan Mihail RADU RUSU, Marius Giorgi USTUROI, Roxana Nicoleta RAȚU, François DJITIE KOUATCHO, Gabriel Vasile HOHA, Alexandru USTUROI, Claudia PÂNZARU, Ana LEAHU, Mircea OROIAN, Sorina ROPCIUC
Bromelain is a vegetal originating enzyme known for its effects on meat tenderization. The purpose of this study was to investigate to which extent the treatment with two sources of bromelain affects the histological properties of pork loin (myocytes integrity, proportion of connective and pure muscular tissues) as well the textural ones (shear force) and its technological parameters (drip loss and cooking yield). Forty-five slices of swine Longissimus dorsi muscles (10 mm thickness) were used as biological material, randomly assigned to a control group (CG-no bromelain hydrolytic treatment-15 slices), to B1 group (triturated pineapple, diluted with distilled water 1:1, resulting 50% aqueous extract - 15 slices kept in marinade 12 hours) and to B2 group (bromelain 1% aqueous solution prepared from commercial food additive, bromelain powder of 2000 GDU/g - 15 slices, kept in marinade 12 hours). Tissue square pieces were sampled from the center of the loins and submitted to paraffin impregnation technique, followed by a hematoxylin, eosin, methylene blue staining and studied via photonic microscopy for the histometric assessments. Cubic samples of were also cut from each slice and submitted to a shear force reading cell. Water holding capacity was then measured on the meat provided by half of the remained slice surface, using the grinding-centrifugation technique while cooking yield was calculated after samples weighing and cooking through deep frying at 250°C into sunflower oil, during 15 minutes. The results suggested that bromelain treatments affected the histological integrity of the samples, more than 17.5 % of endomysium being hydrolyzed in experimental groups, compared to control one. This resulted in apparent increase of the surface occupied by muscular tissue (+6.92% B1vs. CG and +13.18% B2 vs. CG) (P<0.05; P<0.01), versus the one occupied by the connective fibers, as observed and measured within the microscopic field. Bromelain treatments induced better tenderness, suggested by lower instrumentally measured shear force (52.13 N in CG, 48.52 N in B1 and 44.48 N in B2). However, better water holding capacity was measured in CG (WHC=16.78%) due to less tissue disintegration, compared to experimental groups B1 (WHC=14.21%) and B2 (WHC=13.47%) (P<0.05). The cooking yield was consequently better in CG (CY=74.35%), due to lower exudation than in enzymatically treated meat (B1, CY=71.82%; B2, CY=70.25%). Therefore, bromelain enzymatic treatment improves the histological and, subsequently, textural features of pork loin, while the technological properties were reduced by the enzymatic proteolysis. It still remains to investigate to which extent the textural improvement is justified by loss of technological properties and by certain taste and flavor expected alterations, due to the known bromelain bittering potential.
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