ELABORACIÓN DE UN HIDROLIZADO DE PROTEÍNA DE ANCHOVETA (Engraulis ringens) EN POLVO

El objetivo del trabajo fue elaborar un hidrolizado de proteína en polvo utilizando anchoveta sin cabeza y eviscerado (HG) y determinar sus características sensoriales, físico-químicos y microbiológicos. En el proceso de hidrólisis se evaluaron siete proteasas comerciales. La actividad hidrolítica de las proteasas fue evaluada utilizando los valores de grados Brix no corregido (oBx ref.) y grado de hidrólisis (GH%). El flujo experimental para elaborar el hidrolizado en polvo fue: recepción de anchoveta HG, lavado, molido, pesado y mezclado, adición de proteasa y agua, hidrolizado con agitación, filtrado, centrifugado, deshidratado, envasado y almacenado. Las proteasas comerciales que presentaron mayor GH% sobre las proteínas de anchoveta fueron Protex 6L y Protamex con Flavourzyme 1000L. Las dosis de Protamex 0,2 % y Flavourzyme 1000L de 0,4 % respectivamente, en relación al peso de la materia prima, alcanzaron los mayores valores de oBx ref. (11,50) y GH% (39,0 %) a las 2 horas de proceso. El hidrolizado de proteínas de anchoveta en polvo presentó textura de polvo y suave al tacto, de color beige con tonos claros. El sabor y olor fueron ligeros a pescado. Presentó 77,13 % de proteína, 10,727 g de lisina/100 de producto y la baja carga microbiana confirmo las adecuadas condiciones sanitarias en su elaboración.

Spatial and Temporal Variability of Parasite Communities: Implications for Fish Stock Identification

The spatial and temporal variability of parasite communities have received little attention when used as biological tags for identifying fish stocks. This study evaluated the potential spatial and temporal variability of the parasite communities affecting three marine fish species collected between 1993 and 2017. To avoid the potential effect of host age in parasite communities, individuals of similar ages were selected: 1123 Engraulis ringens (12–24 months old), 1904 Trachurus murphyi (24–36 months old), and 630 Merluccius gayi (36–48 months old). Most taxa show differences in the prevalence at the spatial and temporal scales, but the prevalence of some larval endoparasites remains constant at the temporal scale. At the spatial scale, an analysis of similarity (ANOSIM) showed differences in the parasite communities of three species; a canonical analysis of principal coordinates (CAP) showed low values of correct allocations (CA; ≈50%) and values of allocation due to chance (AdC) were lower than the CA. At the temporal scale, an ANOSIM showed differences between the three species. A CAP showed low values of CA (≈50–60%) and the AdC was always lower than CA. Samples at the spatial scale were well allocated to their localities or nearby localities, suggesting a spatial stability. Samples from different years were not well discriminated, suggesting temporal variability. Therefore, in studies regarding parasites as a tool for stock identification, temporal variability must be taken into account.

Kinetic study of a commercial lipase for hydrolysis of semi-refined oil of anchovy (Engraulis ringens) [Estudio cinético de una lipasa comercial para la hidrólisis de aceite semirrefinado de anchoa (Engraulis ringens)]

Lipases due to their ecological nature and catalytic versatility, are ideal for their application in the fish oil hydrolysis industry due to their selective property, which allows the preservation of polyunsaturated fatty acids (PUFAs) in the lipid structure. The objective of this research was to determine the activity and kinetic parameters of a commercial AY AMANO "30SD" lipase, as well as the temperature and time values ​​to achieve an optimal degree of hydrolysis in semi-refined anchovy oil. The experiments were carried out in a jacketed minireactor with a working volume of 400 mL (oil-water-enzyme) with temperature control and pH 7.00, enzyme concentration 350 U/mL and stirring 160 rpm. A 3x3 factorial design and the response surface methodology were used. The results obtained from the study of the enzyme were: activity = 37 384.55 ± 395.07 U/g and kinetic parameters: Km = 7.98 g/L and Vmax. = 0.038887 g/Lxmin. Correspondingly, the following optimal parameters were obtained: Degree of hydrolysis 4.01%, temperature 46.86 °C and hydrolysis time 90 minutes, with a confidence level of 95% (p <0.05). Conclusions: The study allowed us to kinetically characterize the commercial lipase and determine the optimum degree of hydrolysis of the semi-refined anchovy oil.

ICTIOPARASITOLOGÍA MARINA EN EL SISTEMA DE AFLORAMIENTO DE LA CORRIENTE DE HUMBOLDT: DESAFÍOS PARA LA REVISTA NEOTROPICAL HELMINTHOLOGY

El Sistema de Afloramiento de la Corriente de Humboldt, definido como “a Large Marine Ecosystem”, se extiende a lo largo de la Costa Occidental de América del Sur, desde la zona Centro Sur de Chile (app. 42°S) hasta el Norte del Perú (4°S). Es uno de los mayores sistemas de afloramiento del mundo y responsable por los extraordinariamente altos niveles de producción. Es considerado un sistema clase 1, altamente productivo (>300 g·C/m2-año). Los altos valores de producción primaria de este sistema soportan las más grandes pesquerías a nivel mundial (Alheit & Bernal, 1993). Alrededor del 18-20% de las capturas mundiales provienen de este sistema, específicamente de pelágicos pequeños como anchoveta (Engraulis ringens Jenyns, 1842), sardina (Sardinops sagax (Jenyns, 1842)) y jurel (Trachurus murphyi Nichols, 1920). De un sistema de estas características deberá esperarse una alta diversidad biológica.

ICTIOPARASITOLOGÍA MARINA EN EL SISTEMA DE AFLORAMIENTO DE LA CORRIENTE DE HUMBOLDT: DESAFÍOS PARA LA REVISTA NEOTROPICAL HELMINTHOLOGY

El Sistema de Afloramiento de la Corriente de Humboldt, definido como “a Large Marine Ecosystem”, se extiende a lo largo de la Costa Occidental de América del Sur, desde la zona Centro Sur de Chile (app. 42°S) hasta el Norte del Perú (4°S). Es uno de los mayores sistemas de afloramiento del mundo y responsable por los extraordinariamente altos niveles de producción. Es considerado un sistema clase 1, altamente productivo (>300 g·C/m2-año). Los altos valores de producción primaria de este sistema soportan las más grandes pesquerías a nivel mundial (Alheit & Bernal, 1993). Alrededor del 18-20% de las capturas mundiales provienen de este sistema, específicamente de pelágicos pequeños como anchoveta (Engraulis ringens Jenyns, 1842), sardina (Sardinops sagax (Jenyns, 1842)) y jurel (Trachurus murphyi Nichols, 1920). De un sistema de estas características deberá esperarse una alta diversidad biológica.

Evaluating marine reserves as a management policy in the central-southern anchovy (Engraulis ringens) fishery of Chile

The anchovy (Engraulis ringens) fishery in central-southern Chile, like many fisheries worldwide, is overexploitation mainly due to poor and short-term management by fishing authorities and communities. This study proposes and evaluates marine reserves as a possible tool to apply since there is a current marine reserve law in Chile. The study's methodology is the simulation of a bioeconomic model that includes two areas: one is the protected, and the other is the artisanal fishing, in which the protected area transfers biomass to the artisanal fishing area. The reserve is incorporated as a decision variable in the management of this resource. It is determined as a percentage of protection of the total fish population related to fishing effort, which quantifies and evaluates the impact of protecting a stock of parental fish on the fishery's sustainability. Biomass data used is from 2000-2006, during which the anchovy fishery was fully exploited. The carrying capacity and intrinsic growth rate are estimated, and biomass is projected at different protection and effort levels. Results show that if a marine reserve with a protection level of 30% had been applied as a management policy in the anchovy fishery of central-southern Chile in the early 2000s, the fishing activity would be in a state of full exploitation rather than overexploitation as it is today. This model's fundamental contribution is that it makes possible fishery evaluation with real data from the same fishing activity.

Minced products from undersized sea fish: new industrial technology

Introduction. The ever-growing world population and protein deficiency increase the demand for products of animal origin, especially fish-based. However, canned foods and fillets, which are the most popular types of fish products, are made from medium-sized and large fish. In spite of the fact that undersized fish is cheap, it requires manual processing and remains so time and labour consuming that it is utilized for non-food purposes. The research objective was to develop a new technology for processing undersized sea fish into minced ready-to-eat products. Study objects and methods. The study featured experimental samples of fish mince with texturing agents and food additives vs. control samples of pure fish mince. The experiment involved block-frozen Peruvian anchovy (Engraulis ringens L.). The anchovy was minced without pre-defrosting, gutting, or beheading. The experimental and control samples underwent sensory evaluation and were tested for moisture content, water-binding capacity, and rheological properties using a PNDP-penetrometer. Results and discussion. Adding 3.6% of wheat fiber, ≤ 15% of pea flour, ≤ 10% of textured soy, and 12% of onion improved the sensory and technological profiles of the finished product. The recommended mass fraction of fish in the finished product did not exceed 55%, as a higher amount deteriorated the sensory quality of the product. The textured soy provided the optimal texture. The fish balls were cooked from the fish mince, which were deep-fried in breadcrumbs, received a high score for sensory properties and could be recommended as basis for various formulations. Conclusion. Minced undersized fish, traditionally used as fertilizers or crude product, proved to be an advantageous semi-finished and ready-to-eat product. The developed technology is relevant for most undersized block-frozen sea fish.

UNIVERSAL METHOD FOR COMPUTATIONAL MODELING OF THRESHOLD PHENOMENON IN THE NONSTEADY BIOLOGICAL PROCESSES

Context. In modern conditions occur abrupt changes in ecosystems. The species composition of Caspian Sea is changing rapidly. The dynamics of populations acquires an extreme character with the development of rapid invasions. The mathematical description of scale transformations requires new modeling methods. Complicated population regimes of changes have features of the threshold phenomenon in process of its development. Objective. We set the goal of computational modeling of practically important scenarios – groups of situations that relate to extreme and transitional dynamics of ecosystems, like outbreaks at the onset of dangerous invasions. We are developing a method that, on the basis of the survival model of generations, will conduct a description of sudden transitions to rapid but limited outbreak of numbers or, on contrary, a collapse of stocks like Atlantic cod in 1992 or Peruan anchovy Engraulis ringens in 1985. The purpose of our modeling is to improve the accuracy of forecasts of the population size when experts are estimates a rational strategy for the exploitation of biological resources. Method. Situations of abrupt but short-term changes in population processes cannot be calculated by traditional mathematical models and expressed in terms of asymptotic dynamics – closed limit trajectory sets. The basis of the idea of the method proposed by us is the formalization of nonlinear efficiency of reproduction, which changes in a threshold manner only in strictly defined environmental conditions. We use continuous-discrete time in the model for early ontognosis of the cod fish and insect pests. The method with triggers allows us to take into account in simulation experiments logic and motivation of making decisions by experts, people who manage the strategy of exploiting biological resources. Models assess variability for development of situations Results. We have implemented new method of bounded trigger functionals into hybrid system of the equations, that acting in selected specific states of biosystems. Analysis of new model scenarios with modifications of functionals in the basic hybrid system for extreme situations in fish and insect pests is carried out. Conclusions. We consider the method to be universal, since selection of the functional can be adapted to a wide class of models using differential equations on a fixed interval.