Caracterização reológica e microstrutural de emulsões água em óleo para uso alimentar

As emulsões inversas água/óleo são sistemas multifásicos complexos, constituídos por uma fase líquida aquosa dispersa numa fase lipídica (contínua), e cristais de gordura para estabilizar a fase dispersa. O mimetismo lipídico nestas emulsões advém da estabilização através do controlo da cinética da cristalização das gorduras. A natureza e a morfologia das fases formadas estão correlacionadas com as propriedades mecânicas e reológicas destes sistemas. Foram estudadas cinco emulsões inversas água/óleo com diferentes formulações, em duas séries diferentes (2011 e 2013), utilizando diferentes técnicas experimentais, a saber: espectrometria mecânica (ensaios reológicos), microscopia óptica (observação estática e em escoamento torcional), instrumental (cor e textura) e avaliação sensorial. Os ensaios reológicos incluíram ensaios em regime transitório (relaxação de tensões e arranque de escoamento), ensaios em regime dinâmico (determinação do módulo de distorção complexo) e ensaios em regime permanente (escoamento entre pratos paralelos e escoamento Couette), para determinação experimental das funções materiais das emulsões associadas a cada um dos ensaios referidos. A microstrutura e a composição, o tamanho de gota e a distribuição de tamanhos de gota das emulsões inversas foram analisadas e medidas por microscopia óptica e análise de imagem. A visualização de escoamentos e da resposta a diferentes deformações foi efectuada utilizando uma célula óptica de torção acoplada a um microscópio óptico e a uma câmara digital para observação em tempo real das alterações de textura causadas por deformações ou velocidades de deformação (escoamentos). Foi também efectuada avaliação sensorial e instrumental (cor e textura) das diferentes composições das emulsões inversas. A interpretação dos resultados experimentais dos ensaios reológicos foi feita com base no modelo de Palierne, considerando um modelo da emulsão inversa constituída por uma fase lipídica contínua, modificada pela presença da rede de cristais lipídicos, e dois tipos de inclusões da fase aquosa: inclusões “mais flexíveis” com uma interface lípidoágua sem cristais lipídicos, e inclusões “menos flexíveis” onde a interface é modificada pela rede de cristais lipídicos. O ajuste efectuado às funções materiais reológicas mostrou que o modelo utilizado consegue descrever, com boa aproximação, os resultados experimentais obtidos. A caracterização reológica da resposta da emulsão a diferentes histórias da deformação (degrau de deformação, deformação sinusoidal, arranque de escoamento e escoamento permanente) foram complementadas com a observação em tempo real, através de uma câmara digital, das alterações de textura ocorridas em cada um dos ensaios referidos. Foi feita uma avaliação sensorial das diferentes formulações de emulsões inversas consideradas, utilizando um painel de provadores treinado. Através da análise de componentes principais, verificou-se que a avaliação sensorial e a avaliação instrumental são correlacionáveis, e que essas correlações podem ser analisadas em termos das constantes materiais reológicas medidas experimentalmente; Rheological and microstructural characterization of water-and-oil food emulsions ABSTRACT: The water-in-oil (w/o) food emulsions are complex multiphase systems, consisting of a liquid aqueous phase dispersed in a liquid continuous lipid phase and fat crystals to stabilize the dispersed phase. The mimicry of these lipid emulsions stabilization arises by controlling the kinetics of crystallization of fat. The nature and morphology of the phases formed are correlated with rheological and mechanical properties of these systems. Five water/oil emulsions with different formulations were studied on two different series (2011 and 2013), using various experimental techniques, such as: mechanical spectrometry (rheological tests); optical microscopy (torsional static and flow observation); instrumental (colour and texture) and sensory evaluation. The rheological measurements performed assays at transient regime (stress relaxation and start flow), assays at dynamic regime (determination of the complex shear modulus) and assays in steady state (flow between parallel plates and Couette flow), for experimental determination of material functions associated with each of these tests. The microstructure and composition, droplet size and droplet size distribution of w/o emulsions were analyzed and measured by optical microscopy and image analysis. The visualization of flow and response to different strains was performed using an optical shear cell coupled to an optical microscope and a digital camera for real-time observation of texture changes caused by deformation or strain rates (flows). Was also carried out sensory and instrumental evaluation (colour and texture) of different compositions of inverse emulsions. The understanding of the experimental results of the rheological measurements was established on Palierne model considering a inverse emulsion model comprising a continuous lipid phase, modified by the presence of crystals lipid network, and two kinds of aqueous phase enclosures: enclosure "more flexible "with a lipid-water interface without lipid crystals, and enclosure "less flexible" where the interface is modified by the lipid crystal network. The adjustment of rheological material functions showed that the model used can describe the experimental results with close approach. The rheological characterization of the emulsion response to different deformation history (strain step, sinusoidal deformation, start flow and continuous flow) were complemented with the observation of texture changes occurring in each of the tests in real time using a digital camera. Was performed a sensory evaluation of inverse emulsions different formulations using a trained taste panel. It was found by means of principal component analysis that the sensory and instrumental evaluation are correlated, and these correlations can be analysed in terms of rheological material constants experimentally measured

Chemical and microbiological stability of the low caliber apple slices prepared by osmotic dehydration

Osmotic dehydration has received greater attention in recent years as an effective method for fruits and vegetables preservation. Process for preparation of Royal Gala apple slices using osmotic dehydration was standardized. The study was carried out with seleted apples of smaller caliber, produced in the Alcobaça region. For this study apples were seleted by their degree of maturation and absence of mechanical damages. Fully apple fruits were peeled and slices of 4 mm thickness were prepared. The apple slices were immersed in a sucrose solution (50% w/w) and in sucrose/sodium chloride solutions with NaCl concentrations (1% and 3%). After 4 h soaking, quick washing, blotting, the samples where drying at 20 °C up to constant weight. The dried products were packed in glass containers and stored at ambient conditions. The chemical and microbial and stability were monitored for 6 months. The osmo-dried apple slices prepared with 50% sucrose/1% sodium chloride showed an overall chemical acceptability (aw of 0.192; °Brix of 26.3; pH of 3.82; Na content of 0.51g/100g). Microbiologically the product was stable (aerobic mesophile osmotolerant or osmophilic bactéria counts < 2.75 log cfu g-1; fungi counts < 1.75 log cfu g-1) and safe (Clostridium spores and Staphylococcus were not confirmed in this study) up to 6 months of storage at ambient conditions.info:eu-repo/semantics/publishedVersio

Soluções de valorização de resíduos e subprodutos agroalimentares

Apresentação em painelO projeto mobilizador de I&DT “BIOma – Soluções integradas de BIOeconomia para a Mobilização da cadeia Agroalimentar” reúne um consórcio alargado de 24 entidades nacionais inseridas na fileira agroalimentar, tais como hortofrutícolas, vitivinícola e azeite, entre outros, com o desígnio de reposicionar as empresas da cadeia de valor agroalimentar (CVAA) em patamares mais competitivos e sustentáveis, promovendo estratégias e um ecossistema que potenciem de uma forma inovadora a adoção de soluções integradas de Bioeconomia. O Instituto Politécnico de Santarém é responsável pelo suporte técnico à Atividade 1 da PPS3 do projeto, cujo objetivo é desenvolver novos produtos alimentares a partir de subprodutos hortofrutícolas.N/

Used food oils: physical-chemical indicators of quality degradation

Comunicação apresentada em 11th Baltic Conference on Food Science and Technology “Food science and technology in achanging world” FOODBALT 2017 Conference Proceedings. Jelgava, LLUUsed food oil (UFO), designated as frying oil, is a residue. Degradation by reuse or during storage, may occur by contacting, chemical, enzymatic and microbiological pathways, but oxidation is a major concern of the industry, as it affects sensory and nutritional quality of edible oils, with potentially toxic compounds formation. In Portugal, UFO's main destination still is the sewerage system, an environmental problem and waste of raw material, which can be re-qualified for non-food uses. However, quality control applied to UFO's, often results into expensive analysis inappropriate for small laboratories and catering industry. This project, developed with the Musketeers Group Portugal co-promotion (2012-2016), aimed to identify low-cost physicochemical parameters for further implementation as UFO's Quality Degradation Indicators (QDI) indicating defects quickly and accurately. UFO's analysis was tested on the use, for industrial frying, and by degradation induced in the laboratory (frying and heat stability tests) by applying following parameters: moisture, water activity (a(w)), total acidity, peroxide index, iodine index, colour (CIE, CIE Lab), UV absorbency, total polar compounds and microbiological indicators. Internal procedures (ESAS) were validated, redefining working ranges and test conditions, as standards procedures did not provide reliable results for the entire life cycle of oils, whose profile changes with time and reuse. Results demonstrate significant differences with quick response parameters as Total Acidity, Peroxide Index and CIE Lab colour, outlined as QDI's. Moisture, aw and CIE Lab colour proved to be inadequate for this purpose. Iodine Index and UV Absorbency are more complex and time-consuming and were profiled as reference methods.info:eu-repo/semantics/publishedVersio

Strawberry spread - New Food New Tech

This study is part of the Agrio et Emulsion project (POCI-01-0145-FEDER-023583), new food emulsions development. The product innovation results from the addition of a strawberry syrup to a spreadable cream of vegetable origin. Four formulations have been developed and eight syrup spreadable cream, being selected a prototype evaluated by an untrained panel taster. Physicochemical and proximal analyzes were performed: pH, total acidity, soluble solids, energy, moisture, crude protein, total lipids, carbohydrates, fiber and ash. A set of microbial populations was evaluated for microbiological stability control: enumeration of microorganisms at 30 ºC; enumeration of lipolytic microorganisms at 30 ºC; enumeration of Enterobacteriaceae; enumeration of osmophilic or osmotolerant yeasts and moulds; detection of spores of sulfite-reducing Clostridia. Two emerging technologies, ionizing irradiation and hyperpressure were used to study the stability of this new product. The results for the treated and untreated products showed no significant differences. The untreated samples remained stable and showed satisfactory microbiological characteristics under refrigeration at 5 °C after 3 months. Following these results, we conclude that product stability can be ensured by good manufacturing practices.info:eu-repo/semantics/publishedVersio

Agrio et Emulsio – development of new products with vinegar and sweetpotatoes

Agrio et Emulsio project (POCI-01-0145-FEDER-023583) develops in vinegar and food emulsions areas. In line Agrio, vinegar technological ability enables the development of multiple products, by fermentative and non-fermentative prototyping. Articulating technological, laboratory and sensory tests and inspired both by the marinades in wine or vinegar of the Mediterranean gastronomy and in the traditional Portuguese recipe of “drunk” pear in red wine, two prototypes are undergoing final development, using sweet potato cultivars (Ipomoea batatas) as main ingredient. A sweet and sour “drunk” pickle has been developed by fresh pack pickling technology (without fermentation), using a spicy red wine vinegar with cinnamon and black pepper, sweetened with brown sugar and added Gin. The marinade was designed to be a ready-to-eat vegan product, with tofu and sweet potato previously salted in brine and then submerged in the marinade liquid. The marinade matrix is a diluted blend of red wine vinegar and regional liqueur wine from Ribatejo, flavored with red pepper, herbs and spices. Pre-salting in brine, maturation and the final heat treatment are fundamental for the quality and safety of both prototypes that were designed to provide innovation and convenience: new products with long shelf life, aims the preservation of seasonal/surplus raw materials.info:eu-repo/semantics/publishedVersio

Agrio et Emulsio – development of fruity mustard creams

Agrio et Emulsio project (POCI-01-0145-FEDER-023583) presents an proposal in the areas of vinegar products and food emulsions. Combining technical features with mediterranean traditions and Nouvelle Cuisine, two prototypes of fruity mustards are undergoing final development, valuing regional raw materials and profiling into the gourmet/vegan/veggie markets. Mustard creams are oil-in-water emulsions but its practice is linked to vinegar traditions since the thirteenth century, in France, with the foundation of the first confraternity of Maîtres Vinaigrier-Moutardier. Thus, by applying the ancestral practice, mustard (seeds, fragments, powder) was first submitted to maturation studies, varying the type of vinegar and the time of immersion/contact. Maturation reached equilibrium on the 16th day, but pH evolution shows a practically stationary state from the 7th. Best results were obtained with seeds and powdered mustards in red wine vinegar, 4 %(m/v) acidity. The assays were carried out at room temperature using Sinapis Alba (Linnaeus) mustard species. Prototyping articulated technical, analytical (physicochemical, rheological, microbiological) and sensory tests. Each final prototype has a distinct profile of ingredients, mustard, fruits (raspberry and beet or blueberry), olive oil, water, salt, sugar, honey and spices. Both creams retain the sui generis taste of mustard tinted with the fruit flavour plus an innovative pink colour.info:eu-repo/semantics/publishedVersio

Avaliação da qualidade dos figos de uma variedade de “Figo Lampo” com diferentes tempos de refrigeração e de prateleira

Pretendeu-se avaliar o comportamento de uma variedade de figo lampo com o objetivo de determinar o potencial de comercialização no mercado interno e principalmente no mercado externo. Um dos principais problemas dos figos para comercialização em fresco é a sua grande perecibilidade pós-colheita, quer refrigerados quer em prateleira, quer conjugando as duas situações. Foi realizado um ensaio de campo num pomar de figo Lampo, localizado em Cachoeiras, Vila Franca de Xira, no qual foram colhidos 300 figos para avaliação, separados em 2 lotes: Lote A (mais maduros); Lote B (mais verdes). Os figos foram colocados sob condições de refrigeração e de prateleira. Os indicadores de qualidade foram: calibre, massa, Brix e firmeza. Os resultados obtidos para firmeza e Brix correspondentes aos dias de frio e de prateleira a que os figos foram sujeitos permitiram também avaliar o estado de maturação. Constatou-se que é possível a comercialização para o mercado externo até 4 a 5 dias de armazenamento. Relativamente ao mercado interno é possível colher a fruta madura, mas a comercialização e o consumo devem ser imediatos, pois nesse caso, a vida útil diminui, no máximo três dias, não devendo ultrapassar os 2 dias de frio.The main goal of this work is to evaluate the behaviour of a variety of lampo fig in order to determine the commercial potential in the domestic market and especially in the export market. A major problem for producers of fresh figs is its great perishable postharvest either refrigerated or shelf life, or combining the two. It was intended with this work, at the request of a producer’s organization, assess Fig behaviour Burro over several days of cold and days of shelf, in order to determine its commercial potential in the domestic market, especially in external market. It was carried out a field trial in a fig orchard , located in a village of Vila Franca de Xira county, where there were evaluated 300 figs, separated into 2 different lots, according to its ripeness (green and ripe). Figs were put under refrigeration conditions and the shelf. After analyzing the cold storage and the shelf life days which the figs were subject, assess their degree of ripeness, the texture parameters and Brix, it was concluded that for the foreign market the shelf life is on average four to five days if the cold storage is below four days. For the domestic market it is possible to harvest the ripe fruit, but the distribution and consumption should be immediate. In this case, the shelf life decreases to three days, and the cold storage must not exceed 2 days.info:eu-repo/semantics/publishedVersio

Physical-chemical and rheological characterization of tomato (Solanum lycopersicum L.) of Algarve and West

Este estudo teve por objetivo avaliar as caraterísticas físico-químicas e reológicas de duas variedades de tomate, Vimeiro e Runner, cultivados no Algarve e Oeste, ao longo da época de colheita. As amostras foram submetidas à análise do peso, calibre, humidade, sólidos solúveis totais, acidez titulável total, licopeno, cor e dureza. Observaram-se diferenças significativas para todos os parâmetros quando considerados os fatores produtor x variedade x região. Para licopeno e dureza não se observaram diferenças significativas entre variedades e regiões. A análise de componentes principais permitiu identificar 3 clusters, onde a região foi considerada um factor diferenciador. As amostras pertencentes ao cluster 1, variedade Vimeiro produzida no Oeste, revelaram maior peso e calibre e apresentaram uma cor mais intensa e próxima do vermelho. As amostras representadas no cluster 2, variedade Runner produzida no Oeste, revelaram um teor de humidade significativamente superior às restantes modalidades. O cluster 3, amostras da região do Algarve da variedade Runner, encontrou‑se fortemente marcado pela coordenada H°. No que respeita à coordenada de cor a*, os desvios padrão foram elevados em ambas as regiões, mas mais acentuados no Algarve, revelando alguma heterogeneidade dos frutos. De um modo geral verificou-se que o tomate produzido no Oeste apresentou características diferenciadoras, sobretudo no que respeita à homogeneidade de amostras e, peso e calibre superiores.The objective of this study was to evaluate the physico-chemical and rheological characteristics of two tomato varieties, Vimeiro and Runner, grown in Algarve and West of Portugal, during the harvest season. The samples were submitted to analysis of weight, caliber, moisture, total soluble solids, total titratable acidity, lycopene, color and hardness. Significant differences were observed for all parameters when considering the factors producer X variety X region. For lycopene and hardness no differences notorious between varied and regions were observed. The principal components analysis identified 3 clusters. Regarding to cluster 1, Vimeiro variety produced in West of Portugal, higher weight, higher caliber and a more intense and red color were found. In the cluster 2, Runner variety produced in West of Portugal, samples shows a moisture content significantly higher. Cluster 3, Runner variety produced in Algarve, is strongly marked by the coordinate H°. The standard deviations associated with the color coordinate a * were accentuated in the two regions, but more representative in the Algarve, revealing some heterogeneity of the fruits. It is concluded that the tomato produced in the West presents differentiating characteristics, especially with respect to the superior weight and caliber.info:eu-repo/semantics/publishedVersio

Influência da embalagem a vácuo e do processamento a alta pressão na estabilidade do carapau seco

Para valorização do carapau seco e rentabilização de equipamento para processamento a alta pressão, estudaram-se as influências do embalamento a vácuo, ou deste com o processamento e a alta pressão (400 MPa, 5 min), na estabilidade do produto, aos trinta dias após processamento. Para avaliação da estabilidade realizaram-se análises físico-químicas (cor, pH, azoto básico volátil total, cinza total e humidade), microbiológicas (contagem de microrganismos a 300C) e análise sensorial. Entre carapaus, carapaus embalados a vácuo e carapaus embalados a vácuo e submetidos a processamento a alta pressão: o azoto básico volátil total foi superior no embalado a vácuo; a humidade foi mais elevada nos carapaus não processados; o processamento a alta pressão aumentou o brilho e tornou os carapaus esverdinhados e amarelados; o vácuo aumentou a intensidade da cor; e foram preferidos os carapaus não processados. Os valores do azoto básico volátil total e da contagem de microrganismos a 30ºC indicam que o HPP retardou a degradação microbiológica.----To add value to horse mackerel and to maximize use of high pressure processing equipment, we studied the influence of vacuum packaging alone or combined with high pressure processing (400 Mpa, 5 min) on the product’s stability, 30 days post processing. To evaluate stability physichochemical (colour, pH, total volatile basic nitrogen, ash and humidity), microbiological (total count at 30ºC) and sensory analyses were carried out. Between mackerel, vacuum packed mackerel and vacuum packed and high pressure processed mackerel: total volatile basic nitrogen was higher in vacuum packaging; humidity was higher in non-processed mackerel; high pressure processing increased brightness and turned the fish greenish and yellowish; vacuum increased colour intensity; non-processed mackerel was preferred. Total volatile basic nitrogen and total count at 30ºC showed that high pressure processing delayed microbiological deterioration