The objective of this study was to evaluate the effect of different weights of Nile tilapia (Oreochromis niloticus) on yield and quality of smoked and in natura fillets, with and without skin. One hundred tilapias, divided into three weight classes (C1=500-600g; C2=601-700g; C3=701-800g) were used. Two fillet types, with skin and without skin were removed from each sample, salted and hot smoked. Weight affected yield of in natura (C1 = 38.54; C2 = 40.23 e C3 = 40.47%) and smoked fillets (C1 = 22.97; C2 = 24.51 e C3 = 24.68%), and in natura fillet mass index (C1 = 36.69; C2 = 39.45 e C3 = 41.18 g.cm-2). The latter was higher in classes C2 and C3. Fillet with skin had a higher (p<0.05) water activity (0.99) rate than that of fillet without skin (0.98). Salt rate was higher (p<0.01) in smoked fillets than in natura ones. It was observed higher salt levels in the C1 skinless class. With the exception of a* and b* in natura fillet, no difference was reported in color. Smoked fillets from C3 class fish were more acceptable by judges. In larger fish the equation Y= -21.52 + 0.16034X (r=0.80), where X is the weight of fish, may be employed to calculate smoked fillets size, while Y= -17.74 + 0.14198X (r=0.81) for smoked skin-less fillets. Regardless of skin presence, the smoked fillets from largest fishes (C2 and C3 classes) yielded better results (approximately 24%), as well as in the sensorial analysis, related to salt ratio and general acceptance. Fillets in natura showed low values to a* and b*. Weight classes and skin presence in the fillets had no influence in composition, but caused a variation in their area and thickness. The largest fillets were with skin, belonging to class C3.
Nile tilapia (Oreochromis niloticus); fillet mass index; fillet area; sensorial analysis; proximate composition; smoking
