Personne : Turgeon, Sylvie
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Université Laval. Département des sciences des aliments
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- PublicationAccès libreCharacterization 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, SylvieWater 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 libreAcceptability of insect ingredients by innovative student chefs : an exploratory study(Amsterdam : Elsevier, 2021-05-08) Dion-Poulin, Alexandra; Turcotte, Mylène; Lee-Blouin, Sophia; Provencher, Véronique; Doyen, Alain; Turgeon, Sylvie; Perreault, VéroniqueBackground: In Western societies, the acceptability of entomophagy is low despite the sustainable and nutritional benefits of insects. It is recognized that insect meals incorporated in into familiar foods increases willingness to eat insects. Chefs can offer positive culinary insect-based experiences to their customers which can then contribute to increasing the acceptability of entomophagy by consumers. However, little is known about chefs' perceptions of the use of insect-based ingredients. Objective: The aim of this study was to explore the reasons why innovative student chefs are willing (or not) to incorporate mealworms meals into their dishes. Methodology: Semi-structured interviews were conducted with 7 innovative student chefs at the Institut de tourisme et d'hôtellerie du Québec (ITHQ). Thematic analysis based on a priori Rogers' Diffusion of Innovation Theory was conducted using transcript verbatim. Results: Most participants had a past consumption experience with entomophagy and all of them had a positive attitude toward this practice. The main perceived disadvantages of mealworm meal was the texture (granular and uneven), the odor as well as the low acceptability by consumers. Despite that, student chefs were generally willing to use insect-based ingredients, but they thought that transparency and more opportunities for consumers to try good insect-based dishes are keys to enhancing the acceptability of insect consumption. Conclusion: Understanding perceptions of innovative chefs about the use of insect-based ingredients can help to promote their use in gastronomy and ultimately improve their acceptability by consumers.
- PublicationAccès libreQuantitative 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, SteveIndigenous 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 libreHow 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, SylvieNonfat 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.
- PublicationAccès libreStudying stirred yogurt microstructure and its correlation to physical properties : a review([Oxford] : Elsevier Ltd., 2021-06-19) Gilbert, Audrey; Turgeon, SylvieMicrostructure is an important part of the understanding and the control of food properties as rheological properties, water holding and sensory properties. Stirred yogurt microstructure is being under study for decades. Observations at several length scales have been used to probe the structure. Some methods using optical techniques were recently introduced to provide a quick microstructure assessment of stirred yogurt. This review aims to provide a description of stirred yogurt microstructure and a short overview of the main techniques to characterize stirred yogurt microstructure allowing to highlight their complementarity. In general, stirred yogurt microstructure is described as a suspension of interconnected microgels into a continuous serum phase. While the relationship between yogurt microstructure and its physical and sensory properties has been discussed in numerous reviews, models or studies the impact of microgels sizes on rheological properties, water holding capacity, and creaminess, has not always been confirmed. Even if, other features such as microgels aggregation, shape, and compaction have shown to be involved in sensory or physical properties of stirred yogurt gel, a challenge remains for the characterization of microstructural characteristics of microgels without destructuring the network.
- PublicationAccès libreRelationship 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, SylvieSix 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.