53 research outputs found
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
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