Maria Luiza Rodrigues de Souza

Comparison of six filleting methods and their relation with fillet yield and by-products of Nile Tilapia (Oreochromis niloticus) processing

Current experiment evaluates six filleting methods for Nile tilapia with regard to fillet yield (FIY), ventral abdominal muscles (AMY), hypaxial muscles (HMY), residues (REY), crude skin (CSY), clean skin (CSY) and fleshed (FEY). Methods consisted of: F1 = filleting of whole fish and skinning of the fillet with knife, (WFS); F2 = skinning of whole fish with pliers and filleting (WSF); F3 = headless fish and filleting; skinning of fillet with knife (HFS); F4 = headless fish, skinning with pliers and filleting (HSF); F5 = headless fish; removal of fins; filleting and skinning with knife (HFFS); F6 = headless fish; removal of fins, skinning with pliers and filleting (HFSF). Twenty tilapias were used for each treatment in a completely randomized design. Filleting method affected all analyzed yield. WSF had the best fillet yield and hypaxial muscle (36.58% and 4.22%, respectively); lowest yield was provided by HFS (33.66% and 3.31%, respectively). With regard to abdominal muscle, HFFS (2.00%) and HFSF (2.02%) were the best. In the case of residues, WSF gave the best result (57.96%); HSF was the best method for clean skin and fleshing (4.14% and 45.52%, respectively), with WSF (4,00% and 46.11%) as next to best result.

Influência do método de filetagem e categorias de peso sobre rendimento de carcaça, filé e pele da tilápia do Nilo (Oreochromis niloticus)

RESUMO - O objetivo deste trabalho foi avaliar o efeito do metodo de filetagem (F 1 = retirada da pele com alicate e filetagem; F 2 = filetagem e retirada da pele, com faca e auxilio de alicate) e a categoria de peso (P 1 =250-300 g; P 2 =301-350 g; P 3 =351-400 g e P 4 = 401450 g) sobre o rendimento de carcaca (RC), file (RF) e pele da tilapia do Nilo. Foram utilizadas 48 tilapias, em delineamento inteiramente casualizado. Houve efeito para metodo de filetagem, sendo a media de F 1 (56,43 e 36,67%) superior a de F 2 , 53,46 e 32,89%, respectivamente, para RC e RF. Para categoria de peso, as medias P 1 (56,49 e 37,34%) e P 2 (56,34 e 36,40%) foram superiores em relacao a P 3 (53,27 e 31,98%) e P 4 (53,71 e 33,42%), respectivamente, para RC e RF. Porcentagens de pele bruta, limpa e de descarne foram superiores para F 2 , mas nao houve efeito para as categorias de peso. A filetagem F 1 proporcionou melhores rendimentos e resultados de pele e, para categoria de peso, P 1 e P 2 , maiores rendimentos.

Efeito do peso de tilápia no nilo (Oreochromis niloticus) sobre e rendimento e a qualidade de seus filés defumados com e sem pele

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.

Defumação da tilápia do Nilo (Oreochromis niloticus) inteira eviscerada e filé: aspectos referentes às características organolépticas, composição centesimal e perdas ocorridas no processamento

The objective of the experiment was to evaluate the smoking process effect of whole eviscerated and fillet of Nile tilapia on the organoleptic characteristics (appearance, aroma, color, flavor, texture, salt content and general acceptance), percent weight loss (PP) and proximate composition. FP1 (whole eviscerated fish, 5 hour smoking) and FP2 (fillet, 4 hour smoking) were compared. Scaled, eviscerated fish, FP1 and fillets cut by only one person, FP2 were submitted to brine (30%) and smoking process. Average yield for FP1 and FP2 was 63.98% and 27.11%, respectively. Average loss weight during smoking for fillet (31.33%) was higher, when compared to whole fish (27.04%). Sensorial analysis showed that whole fish was more accepted, regarding flavor and salt content; however, aroma, color and texture were not different between whole fish and fillet. Smoking process reduced moisture and increased crude protein, lipid and ash contents. Losses were higher for fillet, which presented higher crude protein and lower lipid contents compared to whole fish. It was also verified that fillet flavor can be improved by correcting the brine step.

Análise da pele de três espécies de peixes: histologia, morfometria e testes de resistência

This study was carried out to analyse the skin of three species of fish (piavucu Leporinus macrocephalus, pacu prata Mylossoma sp e piraputanga Brycon hilarii) through histological and morphometrical analysis and resistance tests after hardening. Skin samples from the dorsal region were taken and fixed in Bouin solution for 24 hours. They were embedded in paraffin, cut 5 µm thick and stained by Hematoxylin-eosin technique. The cuts were analyzed by light microscopy. A EMIC dynamometer was used for the physical mechanical analysis of the skin in 10 samples, longitudinally oriented from the dorsal region of each specie of fish. The dermis of those fishes has a structural pattern common to teleosts, but the setting and distribution of collagen fibers was different among the analyzed species. The skin dermis thickness differed among the three species by the morphometrical analysis. No difference was observed for the resistance test to traction in piraputanga leather (16.88 N/mm2) as well as in piavucu leather (18.50 N/mm2). The results for the skin of both fish species were higher than those for pacu (11.83 N/mm2). The value of stretching as to the point of rupture was higher for piavucu (52.83%) and piraputanga (60.45%), showing no difference among them, but it was lower for pacu (33.83%). The progressive tearing was greater in pacu skin (36.51 N/mm). The skin of the three analyzed species can be turned into leather for the manufacture of several artifacts.

Efeito da técnica de curtimento e do método utilizado para remoção da pele da tilápia-do-nilo sobre as características de resistência do couro

Um estudo foi realizado com o objetivo de avaliar os efeitos do metodo de remocao da pele do file (com alicate e com maquina) e da tecnica de curtimento (com ou sem sais de cromo, bioleather) sobre a resistencia da pele de tilapia-do-nilo (Oreochromis niloticus). Foram retiradas as peles de 40 tilapias (450 g), 20 com uso de alicates e 20 com auxilio de maquina. Apos o curtimento e a retirada dos corpos-de-prova, as peles foram encaminhadas a um laboratorio aclimatizado (23oC e 50% de umidade relativa do ar) para realizacao dos testes de resistencia em dinamometro EMIC, com velocidade de afastamento entre cargas de 100 ± 20 mm/mm. O metodo de retirada da pele do file nao afetou os resultados dos testes de tracao e rasgamento progressivo. A pele retirada com a maquina apresentou elongacao superior (88,48%) a removida com alicate (71,09%). Peles curtidas com sais de cromo (25,54 N/mm; 12,18 N/mm2) foram mais resistentes que as curtidas sem sais de cromo (bioleather) (13,11 N/mm; 9,89 N/mm2). Peles curtidas por estas tecnicas (com cromo e bioleather) podem ser utilizadas na confeccao de vestuarios, pois as medias dos testes de tracao, alongamento e rasgamento progressivo foram superiores a 9,80 N/mm2, 60% e 14,72 N/mm, respectivamente, valores minimos recomendados para couros curtidos ao cromo.

Extruded snacks with the addition of different fish meals

Tilapia, salmon, tuna and sardine meals were prepared to develop and analyze extruded snacks with residue meal from fish processing. Residue meals were included in five types of corn snacks: control (0% fish meal) and four with 9% tilapia, salmon, tuna and sardine meals. Although moisture, lipids and carbohydrates rates did not differ among the snacks, protein rates increased with the increment of fish meal, reaching 11.85% in the tuna snack. Tuna and sardine snacks had the highest iron levels. The most abundant fatty acids were linoleic, oleic, palmitic, linolenic and stearic acids, with sardine, salmon and tuna snacks presenting the highest values of n-3 series fatty acids. Greater luminosity rate was reported for salmon snack, followed by tilapia, tuna and sardine snacks. The highest sensory acceptance index was verified in tilapia (78.07%) and salmon (72.40%). A 9% addition of residue meals of tilapia, salmon and tuna improved the nutritional value of the snacks.

Fresh pasta enrichment with protein concentrate of tilapia: nutritional and sensory characteristics.

With the goal of developing and characterizing the nutritional and sensory aspects of fresh pasta supplemented with tilapia protein concentrate, four types of pasta were prepared, with inclusion of 0, 10, 20, or 30% of tilapia protein concentrate. Linear effects were observed (P < 0.01) in crude protein, total lipids, ash, carbohydrate, and caloric values; these parameters increased with increasing amounts of tilapia protein concentrate in the pasta. The concentration of Na, P, Ca, Mg, and Zn increased linearly (P < 0.01) in correlation with the increase in protein concentrate content, while Fe content decreased linearly (P < 0.01). In the sensory analysis, texture, overall impression, and the acceptance index demonstrated a cubic regression (P < 0.05), with the inclusion of 20% protein concentrate yielding the best scores. Including up to 30% of tilapia protein concentrate in pasta yields an increased nutritional value, but based on the sensory results, 20% of tilapia protein concentrate in pasta is the recommended maximum level.

Histologia da pele da carpa prateada (Hypophtalmichthys molitrix) e testes de resistência do couro

The objectives of this trial were to analyze the skin histology and to evaluate the influence of tanning technique and the direction removal of samples on skin quality of silver-plated carp (Hypophtalmichthys molitrix). Twenty-three fishes were sacrificed and the skin was removed for tanning. Samples of three fishes were settled in formol 10% and, after inclusion in paraffin, the samples were cut with approximately 5 mm of thickness and colored by the hematoxylin-eosin technique (HE). After skin tanning, the samples were removed for resistance tests. The tests were done with EMIC dynamometer, at removal speed of 100 ± 20 mm/mm, in a climatized environment (23oC) and 50% air relative humidity for 24-h period. The skins tanned with chromium salts showed greater resistance to tensile strenght (16.96 N/mm2), elongation (51.49%) and progressive tearing (16.75 N/mm) than those tanned without chromium salts (tensile strenght = 9.12 N/mm2, elongation = 17.48% and 11.36 progressive tearing = N/mm). No effect of direction removal of samples on tensile strenght, elongation, rupture load, progressive tearing, maximum force, and force load was observed. The tanning technique (with or without chromium salts) affect the resistance of the silver-plated carp skin. The technique with chromium salts results in bigger resistance to leather.

Preparation of Extruded Snacks with Flavored Flour Obtained from the Carcasses of Nile Tilapia: Physicochemical, Sensory, and Microbiological Analysis

ABSTRACT This study aimed to develop extruded snacks including flour obtained from Nile tilápia carcasses, and then evaluate the chemical composition, colorimetry, thiobarbituric acid reactive substances, and microbiology. There was a significant increase in the levels of crude protein, ether extract, ash, and minerals, as well as a reduction in carbohydrates as more flour was included in the snacks. Increased levels of flavored flour caused reduction in the brightness of snacks. Oxidative rancidity was not detected in snacks. The inclusion of flour improved the nutritional value of extruded snacks without changing sensory characteristics. Microbiologically, the snacks are suitable for human consumption.