ESTABILIDADE QUÍMICA E MICROBIOLÓGICA DE "MINCED FISH" DE PEIXES AMAZÔNICOS DURANTE O CONGELAMENTO

Foi estudada a estabilidade química e microbiológica de "minced fish" produzidos, em condições industriais, com espécies de peixes da Amazônia: aracú-comum (Schizodon fasciatus), branquinha-comum (Potamorhina latior), branquinha-de-cabeça-lisa (P. altamazonica), curimatã (Prochilodus nigricans), jaraqui-de-escama-fina (Semaprochilodus taeniurus), jaraqui-de-escama-grossa (S. insignis), mapará (Hypophthalmus edentatus), pacú-comum (Metynnis hypsauchen), pacú-manteiga (Mylossoma duriventre) e pirapitinga (Piaractus brachypomum), durante 150 dias sob congelamento a -18±1°C e -36±1°C. Com base no pH, nitrogênio das bases voláteis totais (N-BVT), substâncias reagentes ao ácido tiobarbitúrico (TBARS) e contagens de aeróbios mesófilos a 35°C e psicrotróficos a 7°C, e de coliformes totais e fecais (NMP), os "minced fish" obtidos a partir das espécies de peixes estudadas e de misturas de espécies (aracú+curimatã+pirapitinga; jaraqui+branquinha) mantiveram-se em condições de consumo, durante o período experimental. Os resultados obtidos são altamente promissores sob o ponto de vista tecnológico.

Nutritional characteristics of amazonian fish fat (Colossoma macropomum) and its effect on lipid metabolism of rats fed hypercholesterolemic diets

The effects of fat from tambaqui (Colossoma macropomum), an Amazonian fish, on some nutritional and lipid parameters in rats were evaluated. Weaned Wistar rats were fed for 6 weeks with hypercholesterolemic diets containing 7.5% of soybean oil (SO), cod liver oil (CO), lard (LA), or tambaqui fat (TF). Food consumption, weight gain, and food conversion were measured weekly. Plasma triglycerides was determined at the beginning and on the 6th week of experiment. Plasma cholesterol was determined at 0, 2, 4 and 6 weeks. After the sacrifice, hepatic lipids (triglycerides and cholesterol) and plasma triglycerides, total cholesterol and HDL fractions were determined. Food consumption and weight gain were the same for all groups. There were no differences in plasma triglycerides among the four groups in the 1st and 6th weeks. Regarding the cholesterolemia, TF animals were similar to those fed SO diet, significantly lower than in LA group but higher compared to the CO group. The levels of very low density lipoprotein + low density lipoprotein (VLDL+LDL) were higher in the TF and LA groups compared to the CO and SO groups. However, TA fed animals had high-density lipoprotein (HDL) cholesterol levels higher than the CO group. The ratio (VLDL+LDL)/HDL was higher in the LA group when compared with the remaining groups. In the TA group, the triglycerides and cholesterol concentrations in the liver were similar to the SO group. It may be concluded that tambaqui fat is a good dietary source of lipids as a substitute for lard and similar to soybean oil, as far as atherosclerosis risks is concerned.

Effects of grilling on cholesterol oxide formation and fatty acids alterations in fish

Due to the adverse effects of the cholesterol oxidation products for the human health, the search of the occurrence and the quantification of these compounds in foods are considered of great importance. In this paper the effect of grilling in hake and sardine on cholesterol oxides formation and fatty acids alterations was investigated. The main fatty acids determined in both fishes were docosahexaenoic (DHA), oleic, eicosapentaenoic (EPA) and palmitoleic. The total lipids, fatty acids and cholesterol contents were decreased significantly (p < 0.02) after thermal treatment, with simultaneous increase of the cholesterol oxides contents. The cholesterol oxides determined in both species in the present study were: 19-hydroxycholesterol, 24(S)-hydroxycholesterol, 22(S) hydroxycholesterol, 25-hydroxycholesterol, 25(R)-hydroxycholesterol and 7-ketocolesterol. Besides the presence of the cholesterol oxides in raw fishes, there were a greater number of products resulting from the oxidation of cholesterol side chain, a fact rarely observed in foods.

Effect of soaking and cooking on phytate concentration, minerals, and texture of food-type soybeans

The increasing consumption of soybeans due to its bioactive compounds has attracted interest in describing the grain's constituents and variation during processing. Phytate has been the aim of much research since it chelates essential minerals but also has beneficial antioxidant effects. This study evaluated the variation of phytate, calcium, zinc, and iron during soaking and cooking of soybeans. The phytate: Zn and phytate: Fe molar ratios were determined in order to estimate the bioavailability of these minerals. Six food-type varieties were used: BR 36, BRS 213, BRS 216, BRS 232, BRS 155, and Embrapa 48. The samples were soaked in water 3:1 (w/w) for 12 hours at room temperature and cooked. Cooking time was determined by modeling the softening of each variety using fractional conversion. Water content, phytate, and minerals were determined in raw, soaked and cooked samples. The water content of raw grains for all varieties was 9.9 g.100 g-1 increasing to a range of 58.1-63.7 g.100 g-1 after soaking and 63.1-66.0 g.100 g-1 after cooking. Soaking caused a significant reduction in phytate (23-30%), but cooking caused no additional reduction. The phytate: Zn molar ratio was 20 indicating that zinc absorption could be impaired, while the phytate: Fe molar ratio was 8, below the level of compromising absorption

Psychophysical estimation of acid intensity and determination of sweet-acid interaction in a fish paste containing glycerol

In a fish paste made with cooked Brazilian flathead (Percophis brasiliensis), glycerol (17%), sodium chloride (1.5%) and potassium sorbate (0.1%) the following acid percentages: 0.2; 0.4; 0.6; 0.8, 1 and 1.5% w/w were incorporated to determine the relationship between added acetic acid and the sensorially perceived intensity, and the effects of the combination of sweet-acid tastes. Tests for paired comparison, ranking and structured verbal scales for sweet and acid attributes and psychophysical test were carried out. There was a perceptible difference among samples for differences of 0.4 units of acid concentration. Samples indicated as sweeter by 89.47% of the judges were those containing a lesser acid concentration. A reduction in glycerol sweetness when increasing acid levels was observed. Acetic acid reduced the sweetness of glycerol and inversely glycerol reduced the acidity of acetic acid. The data obtained with the magnitude estimation test agree with Steven's law.

Cooking quality of upland and lowland rice characterized by different methods

Rice cooking quality is usually evaluated by texture and stickiness characteristics using many different methods. Gelatinization temperature, amylose content, viscosity (Brookfield viscometer and Rapid Visco Analyzer), and sensory analysis were performed to characterize culinary quality of rice grains produced under two cropping systems and submitted to different technologies. All samples from the upland cropping system and two from the irrigated cropping system presented intermediate amylose content. Regarding stickiness, BRS Primavera, BRS Sertaneja, and BRS Tropical showed loose cooked grains. Irrigated cultivars presented less viscosity and were softer than upland cultivars. Upland grain samples had similar profile on the viscoamylografic curve, but the highest viscosity peaks were observed for BRS Alvorada, IRGA 417, and SCS BRS Piracema among the irrigated cropping system samples. In general, distinct grain characteristics were observed between upland and irrigated samples by cluster analysis. The majority of the upland cultivars showed soft and loose grains with adequate cooking quality confirmed by sensory tests. Most of the irrigated cultivars, however, presented soft and sticky grains. Different methodologies allowed to improve the construction of the culinary profile of the varieties studied.

Evaluation of process parameters in the industrial scale production of fish nuggets

This work reports the use of experimental design for the assessment of the effects of process parameters on the production of fish nuggets in an industrial scale environment. The effect of independent factors on the physicochemical and microbiological parameters was investigated through a full 24 experimental design. The studied factors included the temperature of fish fillet and pulp in the mixer, the temperature of the added fat, the temperature of water and the ratio of protein extraction time to emulsion time. The physicochemical analyses showed that the higher temperature of the pulp and fillet of fish, the lower the protein in the final product. Microbiological analyses revealed that the counting of Staphylococcus coagulase positive, total and thermo-tolerant coliforms were in accordance with the current legislation.

Elimination of Salmonella enterica serovar Typhimurium in artificially contaminated eggs through correct cooking and frying procedures

Salmonellosis is a serious foodborne disease associated with the presence of bacteria in eggs or foods containing raw eggs. However, the use of appropriate procedures of cooking and frying can eliminate this contamination. There are few studies on the elimination of contamination of Salmonella in hens' eggs through typical frying procedures, especially for Salmonella enterica serovar Typhimurium (or S. typhimurium). The aim of this study was to determine the appropriate conditions for cooking and frying hens' eggs artificially contaminated with S. typhimurium, making them free of bacterial contamination. Hens' eggs were artificially contaminated with S. typhimurium and subjected to various processes of cooking, frying and food preparation. It was observed that the minimum time necessary to eliminate contamination through cooking procedures is 5 minutes after the water starts boiling, and also that, cooking in the microwave oven complete eliminates the bacterial contamination. When the eggs were fried on both sides, keeping the yolk hard, a complete bacterial elimination was observed. Mayonnaise prepared with vinegar presented a decrease in bacterial colonies when compared mayonese prepared with lemon.

Culture alternative medium for the growth of extreme halophilic bacteria in fish products

Halotolerant or halophilic (Archaeabacteria) microorganisms can be found in salted and ripening fish products that are not affected by salt. They can be moderate or extremely halophilic bacteria. The extremely halophilic bacteria require between 15-30% of NaCl for growth. The extremely halophilic archaeobacteria may be selectively isolated in different media. The aim of this work was to determine the effectiveness of the Salt-Agar-Milk medium, a medium modified in our laboratory through the addition of MgSO4 and KCl - named SAMm, and its effect on the bacterial growth by means of comparison with other media, with and without milk, determining time of incubation and counting. Two samples of salted fish from local fish salting factories and two laboratory strains were used. The factory samples were matured anchovy and anchovy fillets in oil, and the laboratory strains were: Haloarcula spp. (proteolytic) and Halococcus spp. (non-proteolytic). The following media were alternatively used for the isolation of extremely halophilic bacteria: IRAM; Formulation of Gibbons and collaborators, Cod Milk agar, and SAMm. IRAM and Gibbons were also used enriched with milk. In the SAMm medium, there were obtained count values similar or higher than the ones of the traditional media; besides the simplicity of its elaboration, the possibility to obtain positive results two or three days earlier also added to its benefit. Consequently, it can be considered an alternative to the media traditionally used for the studied halophilic bacteria.

Acid and salt uptake during the marinatig process of Engraulis anchoita fillets influence of the solution: fish ratio and agitation

The aims of this research were to determine the effect of different conditions of the marination stage on the salt and acid uptake, immersion time, and sensorial characteristics during the marinating process of anchovy (Engraulis anchoita). Different solution:fish ratios and the agitation effect during this stage were analyzed. The ratios used were: 0.77:1, 3:1 and 10:1 (with and without agitation). An increase of marinating solution:fish ratio causes a higher speed of acid and salt penetration The product obtained with the 10:1 ratio had a dry and fibrous texture and a slightly salty taste. Salt concentration was statistically significantly lower (p < 0.01) in the samples with agitation. Agitation did not influence the acid uptake, and the salt penetration speed decreased, but rancidity was detected in this product. The ratio 3:1 decreases the marinating time without damaging sensory attributes and can be used in the fish marinating process.

Integration of cooking and vacuum cooling of carrots in a same vessel

Cooked vegetables are commonly used in the preparation of ready-to-eat foods. The integration of cooking and cooling of carrots and vacuum cooling in a single vessel is described in this paper. The combination of different methods of cooking and vacuum cooling was investigated. Integrated processes of cooking and vacuum cooling in a same vessel enabled obtaining cooked and cooled carrots at the final temperature of 10 ºC, which is adequate for preparing ready-to-eat foods safely. When cooking and cooling steps were performed with the samples immersed in boiling water, the effective weight loss was approximately 3.6%. When the cooking step was performed with the samples in boiling water or steamed, and the vacuum cooling was applied after draining the boiling water, water loss ranged between 15 and 20%, which caused changes in the product texture. This problem can be solved with rehydration using a small amount of sterile cold water. The instrumental textural properties of carrots samples rehydrated at both vacuum and atmospheric conditions were very similar. Therefore, the integrated process of cooking and vacuum cooling of carrots in a single vessel is a feasible alternative for processing such kind of foods.

Environment is crucial to the cooking time of beans

The objectives of this study were to understand how genotype, storage time, and storage conditions affect cooking time of beans and to indicate storage techniques that do not affect the cooking time. The grains were subjected to five different storage periods and six different storage conditions. The cooking time was estimated using the Mattson Cooker. The data were subjected to analysis of variance and a subsequent adjustment of simple linear regression for deployment of the interactions between the factors. Contrasts were used to determine the best levels of the factor storage condition. Genotype did not impact cooking time when the storage time and storage conditions were considered. Time and storage conditions affect the cooking time of beans in a dependent manner, but time of storage had the biggest influence. The best conditions for long-term storage of beans ensuring a smaller increase in cooking time is plastic storage at low temperatures. Thus, plastic freezer storage is a practical alternative for consumers.

Application of exploratory factor analysis to assess fish consumption in a university community

The objective of this research was to use the technique of Exploratory Factor Analysis (EFA) for the adequacy of a tool for the assessment of fish consumption and the characteristics involved in this process. Data were collected during a campaign to encourage fish consumption in Brazil with the voluntarily participation of members of a university community. An assessment instrument consisting of multiple-choice questions and a five-point Likert scale was designed and used to measure the importance of certain attributes that influence the choice and consumption of fish. This study sample was composed of of 224 individuals, the majority were women (65.6%). With regard to the frequency of fish consumption, 37.67% of the volunteers interviewed said they consume the product two or three times a month, and 29.6% once a week. The Exploratory Factor Analysis (EFA) was used to group the variables; the extraction was made using the principal components and the rotation using the Quartimax method. The results show clusters in two main constructs, quality and consumption with Cronbach Alpha coefficients of 0.75 and 0.69, respectively, indicating good internal consistency.

Relationship between the price of fish and its quality attributes: a study within a community at the University of São Paulo, Brazil

The aim of this study was to evaluate the associations between the products' market price and attributes related to fish purchase and consumption within a university community in Brazil. A structured questionnaire consisting of a five-point Likert scale was used. It was previously tested and made available to the university community via the Internet. The sample comprised 1966 voluntaries including university students and faculty and staff members. A descriptive analysis of data was performed using Spearman's correlation analysis. The results showed that the majority of the respondents (56%) consume fish at home; some consume fish at restaurants (39%), and 5% at family or friends' houses, reinforcing the idea that variables such as culture and reference groups are fundamental determinants of purchase and consumption behavior. It was identified a significant (p < 0.001) and very strong correlation between the attributes price and nutritional value (r = 0.92); price and availability at the usual places of purchase (r = 0.92); price and packaging (r = 0.92); price and brand name (r = 0.91); and price and of the Federal Inspection stamp (r = 0.91) and a low positive correlation (p < 0.001) between the price variable and the initiative for fish traceability (r = 0.16). This study demonstrated that the price of fish is associated with the quality of the product and the attributes related to it such as packaging, nutritional value, and availability of the product in the market.

Analysis of applicability of Peleg model to the cooking-infusion of mackerel (Scomber japonicus) slices

Mass transfer kinetics in osmotic dehydration is usually modeled by Fick's law, empirical models and probabilistic models. The aim of this study was to determine the applicability of Peleg model to investigate the mass transfer during osmotic dehydration of mackerel (Scomber japonicus) slices at different temperatures. Osmotic dehydration was performed on mackerel slices by cooking-infusion in solutions with glycerol and salt (a w = 0.64) at different temperatures: 50, 70, and 90 ºC. Peleg rate constant (K1) (h(g/gdm)-1) varied with temperature variation from 0.761 to 0.396 for water loss, from 5.260 to 2.947 for salt gain, and from 0.854 to 0.566 for glycerol intake. In all cases, it followed the Arrhenius relationship (R²>0.86). The Ea (kJ / mol) values obtained were 16.14; 14.21, and 10.12 for water, salt, and glycerol, respectively. The statistical parameters that qualify the goodness of fit (R²>0.91 and RMSE<0.086) indicate promising applicability of Peleg model.