Personne : Ratti, Cristina
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Université Laval. Département des sols et de génie agroalimentaire
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- PublicationAccès libreSpray and freeze drying of human milk on the retention of immunoglobulins (IgA, IgG, IgM)(M. Dekker, 2016-03-07) Castro-Albarràn, Jorge; St-Amour, Isabelle; Aguilar-Uscanga, Blanca Rosa; Calon, Frédéric; Saucier, Linda; Solís-Pacheco, Josué; Ratti, CristinaSeveral freeze-drying and spray-drying methods were investigated in relation to the retention of immunoglobulins (Ig) A, IgG, and IgM. Spray drying produced human milk powders with 2% humidity and a good retention of IgG (>88%) and IgM (∼70%). However, only 38% of IgA remained after spray drying. For freeze drying, only the highest heating plate temperature used in this study (40°C) brought IgA content down to 55% in powder with 1.75% residual humidity, whereas milk samples undergoing lower temperatures had higher preservation rates (75% for IgA and 80% for IgG and IgM) and higher residual moisture contents. From these results, it can be concluded that IgA is the most sensitive Ig lost during drying processing of human milk. The best method to generate human milk powders without a significant loss of Ig was thus freeze drying at 30°C heating plate temperature, which accelerated the process compared to lower processing temperatures, but still had good overall Ig retention.
- PublicationAccès libreComparison of black soldier fly larvae pre-treatments and drying techniques on the microbial load and physico-chemical characteristics(Wageningen Academic Publishers, 2021-07-14) Deschamps, Marie-Hélène; Vandenberg, Grant William; Cisse, M'ballou; Ratti, Cristina; Saucier, Linda; Lebeuf, YolaineBlack soldier fly larvae (BSFL) are good candidates for upcycling wet organic residuals. Like other unprocessed raw animal products, BSFL require processing to prevent spoilage and degradation during storage and to facilitate their use as feed ingredients. In this study, hot-air drying and freeze-drying were examined as means to ensure long-term preservation. Pre-treatments of larvae, such as puncturing, blanching (40 s) and scalding (2, 4, 6 and 8 min) in boiling water reduced drying times, most likely by affecting the integrity of the wax-coated cuticle that protects the larvae against desiccation. Overall, the larvae dried two to six times faster using hot-air compared to freeze-drying, and larvae pre-treatments were proven to effectively improve drying efficacy. Pre-treating larvae in boiling water followed by a shorter drying time with hot air was effective at reducing primary and secondary oxidation as well as darkening/browning (colour lightness, L* value) compared to the untreated control (rawthawed) larvae. The larvae pre-treatments in boiling water also led to a significant reduction in microbial load (3.21 to 4.83 log) in the dry product compared to the control. BSFL powder, produced from grinding thawed larvae that were pre-treated for 4 min in boiling water before being dried in hot air (60 °C; 6 h), had a water activity below 0.4. This led to a relatively stable product with limited colour changes over a 30-day storage period. These processing treatments also resulted in a product with no detectable Salmonella and Escherichia coli counts ranging from 100 to 1000 cfu/g. Overall, the powdered BSFL product was deemed suitable to incorporate into pelleted feed under the current regulations in Canada.
- PublicationRestreintThermal properties of duck fatty liver (foie gras) products(Taylor & Francis group, 2016-04-06) Saucier, Linda; Ratti, Cristina; Sanchez Carrillo, FelipeThermal properties of duck fatty liver (foie gras), foie gras emulsion and fatty liver fat, as well as regular duck fat, were determined as a function of temperature. Density of foie gras and foie gras fat and emulsion at 20°C was measured as 947, 836, and 928 kg/m3, respectively. Differential scanning calorimetry thermograms for foie gras fat resulted in melting points ranging from –20 to 40°C. Values for the specific heat at 65°C for the fatty liver, its emulsion and fat, and duck fat were 1.79, 2.38, 1.71, and 2.48 J/g°C, respectively. Thermal conductivity of foie gras (organ) and its emulsion at 40°C was determined as 0.330 and 0.428 W/m°C, respectively. Mathematical models based on composition and temperature were developed for all the thermal properties obtained in this work.