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Personne :
Turgeon, Sylvie

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Turgeon

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Sylvie

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Université Laval. Département des sciences des aliments

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ncf10325454

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Voici les éléments 1 - 10 sur 18
  • PublicationAccès libre
    Relationship between smoothing temperature, storage time, syneresis and rheological properties of stirred yogurt
    (Barking, Essex, England : Elsevier Applied Science, 2020-05-23) Guénard Lampron, Valérie; Villeneuve, Sébastien; St-Gelais, Daniel; Turgeon, Sylvie
    Six different smoothing temperatures were compared for nonfat yogurt and the changes in syneresis and rheological properties observed for up to 22 days. Multiple linear regressions were used to describe the syneresis, firmness, flow time, viscosity, and flow resistance and the relationship between these properties, the smoothing temperature and the storage time. During storage, viscosity, firmness, and flow time increased; syneresis and flow resistance remained stable. Syneresis increased significantly (P ≤ 0.05) with smoothing temperature (10–35 °C). Other properties increased slightly (P > 0.05), and properties started to decrease above 30 °C. Syneresis, viscosity, and flow resistance were more sensitive to smoothing temperature; firmness and flow time were more sensitive to storage time. Lower smoothing temperature (10 °C) should be used to minimize syneresis while smoothing temperature ranging from 25 to 30 °C is better to improve rheological properties. Storage time must be considered to optimize these properties.
  • PublicationAccès libre
    Quantitative PCR reveals the frequency and distribution of 3 indigenous yeast species across a range of specialty cheeses
    (American Dairy Science Association, 2022-09-14) Lamarche, Andréanne; Lessard, Marie-Hélène; Viel, Catherine; Turgeon, Sylvie; St-Gelais, Daniel; Labrie, Steve
    Indigenous microorganisms are important components of the complex ecosystem of many dairy foods including cheeses, and they are potential contributors to the development of a specific cheese's sensory properties. Among these indigenous microorganisms are the yeasts Cyberlindnera jadinii, Pichia kudriavzevii, and Kazachstania servazzii, which were previously detected using traditional microbiological methods in both raw milk and some artisanal specialty cheeses produced in the province of Québec, Canada. However, their levels across different cheese varieties are unknown. A highly specific and sensitive real-time quantitative PCR assay was developed to quantitate these yeast species in a variety of specialty cheeses (bloomy-rind, washed-rind, and natural-rind cheeses from raw, thermized, and pasteurized milks). The specificity of the quantitative PCR assay was validated, and it showed no cross-amplification with 11 other fungal microorganisms usually found in bloomy-rind and washed-rind cheeses. Cyberlindnera jadinii and P. kudriavzevii were found in the majority of the cheeses analyzed (25 of 29 and 24 of 29 cheeses, respectively) in concentrations up to 104 to 108 gene copies/g in the cheese cores, which are considered oxygen-poor environments, and 101 to 104 gene copies/cm2 in the rind. However, their high abundance was not observed in the same samples. Whereas C. jadinii was present and dominant in all core and rind samples, P. kudriavzevii was mostly present in cheese cores. In contrast, K. servazzii was present in the rinds of only 2 cheeses, in concentrations ranging from 101 to 103 gene copies/cm2, and in 1 cheese core at 105 gene copies/g. Thus, in the ecosystems of specialty cheeses, indigenous yeasts are highly frequent but variable, with certain species selectively present in specific varieties. These results shed light on some indigenous yeasts that establish during the ripening of specialty cheeses.
  • PublicationAccès libre
    How do smoothing conditions and storage time change syneresis, rheological and microstructural properties of nonfat stirred acid milk gel?
    (Barking, Essex, England : Elsevier Applied Science, 2020-07-16) Guénard Lampron, Valérie; Bosc, Véronique; St-Gelais, Daniel; Villeneuve, Sébastien; Turgeon, Sylvie
    Nonfat acid milk gel, acidified by GDL, was used to simulate microbial fermentation of milk to produce stirred yoghurt. Acid milk gel preparation at laboratory scale included stirring, pumping, smoothing and cooling operations. Two filters (pre-smoothed, 1 mm; smoothed, 500 μm), three smoothing temperatures (13, 22 and 35 °C) and two storage times (1 and 22 days) were studied. Syneresis, microgels size and smoothness of microgels were analysed for pre-smoothed and smoothed gels; viscosity, storage modulus, firmness and total pore area were only analysed for smoothed gel. After 1 and 22 days of storage, pre-smoothed gels developed lower syneresis and smaller microgels than smoothed gels at 22 °C. For smoothed gels, regardless of the smoothing temperature, syneresis, firmness, microgels size and smoothness increased during storage, while total pore area decreased and viscosity remained stable. Viscosity was lower when smoothing was performed at 35 °C and was correlated to rougher microgels.
  • PublicationRestreint
    Peptides from milk protein hydrolysates to improve the growth of human keratinocytes in culture
    (Elsevier Applied Science, 2004-07-01) Amiot, Jean; Germain, Lucie; Auger, François A.; Ory-Salam, Christine; Lemay, Martine; Turgeon, Sylvie
    Milk and colostrum are known to contain constituents having growth promoting activities on various human cell lines. Peptides from milk protein hydrolysates have also been shown to have various nutraceutical and biological properties. The aim of this research was to establish conditions for the in vitro hydrolysis of milk proteins and for the separation and identification of peptides that could promote growth of human skin cells in culture. Milk protein hydrolysates were obtained by using trypsin and chymotrypsin with various enzyme to substrate ratios (E/S) and degrees of hydrolysis (DH). Peptides contained in a 6% DH hydrolysate obtained with chymotrypsin were separated by size exclusion chromatography and supplemented in in vitro culture media to measure their efficacy to promote growth of keratinocytes isolated from human skin. The results indicated that growth promoting activity was increased up to 108% for keratinocytes cultured in medium supplemented with 300 μg mL−1 of one peptide fraction. Fifteen peptides isolated from this fraction by RP-HPLC and characterized by Pico-Tag amino acids analysis were shown to have an average molecular weight of 800 Da and to contain high concentrations of hydrophobic and aromatic amino acids.
  • PublicationAccès libre
    Disintegration and nutrients release from cheese with different textural properties during in vitro digestion
    (New York : Elsevier, 2016-09-12) Fang, Xixi; Rioux, Laurie-Eve; Labrie, Steve; Turgeon, Sylvie
    Recent results showed that solid food disintegration in the stomach may be affected by food texture which was demonstrated to change during digestion. Cheese is complex as, depending on the variety, its composition and texture can be modulated. Cheddar, light Cheddar, Mozzarella and light Mozzarella cheese particles were digested in vitro. Cheese disintegration and nutrients release were studied throughout the oral, gastric and duodenal digestion steps in presence or absence of enzymes. Cheese disintegration was significantly affected by the enzymatic treatment (with or without enzymes). The addition of enzymes allowed to reach 72% of cheese disintegration at the end of the duodenal digestion while it has attained 30% when no enzymes were added. Cheddar cheese disintegration was the highest among cheeses. This phenomenon was related to its initial higher fat content which resulted in a higher fat release during digestion. The disintegration at the end of each digestion step was also correlated to cheese composition (proteolysis and fat) and to textural parameters (hardness, resilience, adhesiveness and chewiness). Light Cheddar and Mozzarella exhibited similar disintegration and nutrients release at the end of the digestion due to a relatively small fat reduction (6%) which had limited effect on cheese texture. This study provides quantitative evidence regarding the impact of cheese textural changes during digestion on cheese disintegration and macronutrients release which may further affect nutrients anabolic response and some physiological functions.
  • PublicationAccès libre
    Seaweeds : a traditional ingredients for new gastronomic sensation
    (Boca Raton : CRC Press, 2017-02-08) Rioux, Laurie-Eve; Beaulieu, Lucie; Turgeon, Sylvie
    Seaweeds have a long tradition in Asian cuisine. In Canada and US, seaweed consumption is mostly limited to sushi and other imported Asian dish. However, seaweeds are well recognized for their richness in several nutrients such as fiber, protein and minerals. But what is limiting seaweed and seaweed derived ingredients utilization in home cooking? Finding fresh seaweeds within inland cities is one limiting step but also the seaweed marketing need to propel the image that seaweed are not only nutritive but can bring flavor and texture in cuisine dish. With the rise of TV cooking shows, blogs and online recipes hosted by several renowned chefs, it is now time to bring seaweed in the spotlight. The aim of this review is to look at seaweeds to support a wider use in culinary applications for their nutritional contribution but also from a sensory perspective.
  • PublicationAccès libre
    Characterization of syneresis phenomena in stirred acid milk gel using low frequency nuclear magnetic resonance on hydrogen and image analyses
    (Oxford : IRL Press, 2020-04-15) Gilbert, Audrey; Rioux, Laurie-Eve; St-Gelais, Daniel; Turgeon, Sylvie
    Water retention is an important quality attribute for yogurt. Classically, stirred yogurt water retention is investigated using induced syneresis measurement (centrifugation), which does not characterize spontaneous syneresis. Low-frequency nuclear magnetic resonance (1H-LF-NMR) is a non-destructive technique to detect spontaneous syneresis. Experimental yogurt from pasteurized skim milk, and commercial stirred yogurts were analyzed with 1H-LF-NMR. After Laplace's transformation of the signal, hydrogen atoms pools were differentiated according to their mobility. Each hydrogen pool stood for a type of water mobility in the matrices characterized by a relaxation time (T2(i)), and a signal intensity (I2(i)). Yogurt water retention was assessed by induced syneresis and their structure was characterized using microscopy. Low frequency 1H-NMR detected four different water mobility groups in the matrices. Among these, there was a signal from bulk water, and another attributed to the separated serum (spontaneous syneresis). In experimental yogurts, spontaneous syneresis was visible, resulting in induced syneresis higher than 50%. Moreover, induced syneresis and spontaneous syneresis detected by 1H-LF-NMR were similar. In commercial yogurts, bulk water mobility reduced with increasing protein content and protein network density. Induced syneresis and bulk-water mobility correlated only in yogurts without gelatin. In the presence of gelatin, the network was more open, probably favoring bulk water mobility. This study shows that 1H-LF-NMR associated with microscopy image analysis efficiently assesses and describes yogurts water retention and spontaneous syneresis.
  • PublicationAccès libre
    Formation and functional properties of protein–polysaccharide electrostatic hydrogels in comparison to protein or polysaccharide hydrogels
    (New York, NY : Elsevier Science Pub. Co., 2017-02-16) Le, Xuan Thang; Rioux, Laurie-Eve; Turgeon, Sylvie
    Protein and polysaccharide mixed systems have been actively studied for at least 50 years as they can be assembled into functional particles or gels. This article reviews the properties of electrostatic gels, a recently discovered particular case of associative protein–polysaccharide mixtures formed through associative electrostatic interaction under appropriate solution conditions (coupled gel). This review highlights the factors influencing gel formation such as protein–polysaccharide ratio, biopolymer structural characteristics, final pH, ionic strength and total solid concentration. For the first time, the functional properties of protein–polysaccharide coupled gels are presented and discussed in relationship to individual protein and polysaccharide hydrogels. One of their outstanding characteristics is their gel water retention. Up to 600 g of water per g of biopolymer may be retained in the electrostatic gel network compared to a protein gel (3–9 g of water per g of protein). Potential applications of the gels are proposed to enable the food and non-food industries to develop new functional products with desirable attributes or new interesting materials to incorporate bioactive molecules.
  • PublicationAccès libre
    Low-temperature blanching as a tool to modulate the structure of pectin in blueberry purees
    (Journal of food science, 2017-08-10) Chevalier, Laura; Rioux, Laurie-Eve; Angers, Paul.; Turgeon, Sylvie
    Blueberry composition was characterized for 6 cultivars. It contains a good amount of dietary fiber (10% to 20%) and pectin (4% to 7%) whose degree of methylation (DM) is sensitive to food processing. A low temperature blanching (LTB: 60 °C/1 h) was applied on blueberry purees to decrease pectin DM, in order to modulate puree properties and functionalities (that is, viscosity and stability), and to enhance pectin affinity toward other components within food matrices. Fiber content, viscosity, pectin solubility, DM, and monosaccharide composition were determined for both pasteurized, and LTB+pasteurized blueberry purees. The results showed that neither the amount of fiber, nor the viscosity were affected by LTB, indicating that this treatment did not result in any significant pectin depolymerization and degradation. LTB caused a decrease both in pectin DM from 58–67% to 45–47% and in the amount of water-soluble pectin fraction, the latter remaining the major fraction of total pectin at 52% to 57%. A LTB is a simple and mild process to produce blueberry purees with mostly soluble and low-methylated pectin in order to extend functionality and opportunities for interactions with other food ingredients.
  • PublicationAccès libre
    Impact of starch and exopolysaccharide-producing lactic acid bacteria on the properties of set and stirred yoghurts
    (New York (N.Y.) : Elsevier, 2016-01-21) Gentès, Marie-Claude; Turgeon, Sylvie; St-Gelais, Daniel
    The impact of exopolysaccharide (EPS)-producing lactic acid bacteria with well-known structures and starch (0.75%) on the rheological properties (apparent viscosity and elastic modulus) and physical properties (syneresis) of set and stirred yoghurts was studied. Three EPS-producing strains with different structural characteristics were studied: Streptococcus thermophilus ST1 (anionic, stiff and linear EPS), Lactobacillus delbrueckii subsp. bulgaricus LB1 (neutral, stiff and ramified EPS) and Lb. delbrueckii subsp. bulgaricus LB2 (neutral, flexible and highly ramified EPS). The presence of linear, stiff, and anionic EPS from ST1 increased the elastic modulus in all yoghurt conditions, possibly owing to electrostatic interactions with caseins. Higher viscosity values were obtained with stiff and linear or slightly branched EPS from the ST1 and LB1 for all yoghurt conditions. Starch addition increased the values of the rheological and physical properties of all stirred yoghurts, probably due to the repulsion between proteins and polysaccharides favouring thermodynamic incompatibility.