International Journal of Pure & Applied Bioscience, 2019
Appearance is one of the sensory attributes that give first impression regarding a product to the... more Appearance is one of the sensory attributes that give first impression regarding a product to the consumers. Color plays a major role in determining the overall quality of the product. Acidic cakes like lemon cakes are unique in taste and flavor. In this study, changes in color of cakes were analyzed and the effect of pH and sugar on color was evaluated. Cakes were baked at similar processing conditions. Lemon juice and maltitol were added in different proportions by varying water and sucrose respectively with other ingredients. Color of crust and crumb were evaluated on the second day of baking using colorimeter. A significant color difference was observed between samples. Crust color become darker and color intensity of crumb increased on increasing the amount of lemon juice. Reducing sugars produced due to acid hydrolysis of sucrose promotes browning. Maltitol didn’t contribute significantly to the browning reaction.
International Journal of Pure & Applied Bioscience, 2019
Experiments were carried out to study the impact of pressure change during dough mixing with a sp... more Experiments were carried out to study the impact of pressure change during dough mixing with a spiral dough mixer with the possibility of controlling the temperature. Three pressure and spiral tool speed conditions were used in this experiment: 50, 250 and 500 mbar and 100,150 and 200 RPM respectively. The objectives were to understand the effect of pressure and tool speed on dough during kneading in order to optimize dough kneading conditions. The results showed that dough aeration was proportional to the number of rotations of the spiral tool. Higher pressure and higher-speed mixing reduced the time to reach maximum power (tPEAK) means duration of mixing can be reduced. Bread specific volume, porosity fraction and pore size distributions were analysed for a better understanding of the impact of high pressure on bread quality.
La congelation est un procede largement utilise dans les industries agro-alimentaires. La surgela... more La congelation est un procede largement utilise dans les industries agro-alimentaires. La surgelation est un mot qui a ete cree dans les annees 1970 afin d'ameliorer la reconnaissance des produits congeles de qualite superieure ; ce terme a ete defini par un arrete. Il a ete conserve dans les nouveaux arretes issus des directives europeennes. Cependant, l'interpretation de ces arretes et la notion de produit « congele » ou « non congele » reste tres imprecise dans le cas de produits alimentaires complexes et heterogenes; en effet, la cristallisation de l'eau se fait sur une plage de temperature large. L'interpretation proposee s'appuie sur un texte de l'IIF (livre rouge) proposant qu'un produit peut etre considere comme congele lorsque 80 % de son eau est congelee. Une etude de cas realisee sur un produit de type quiche est presentee et montre l'interet de l'approche proposee.
The aim of this work was to investigate different methods of measuring the expansion of bread dou... more The aim of this work was to investigate different methods of measuring the expansion of bread dough during fermentation and to develop a mathematical model to describe the variation of dough volume. Dough was prepared with wheat flour, salt, yeast, and selected amount of water (56%, 58%, and 60% w/w flour basis). Proving time was 1 h and proving temperature investigated were 25, 30, and 35°C. Dough volume was measured with three methods: (1) vertical expansion in a flask, (2) horizontal expansion between two plates, and (3) free expansion method. Volume was measured either using displacement transducer or from image analysis of pictures taken during expansion. All the methods allowed monitoring the increase in dough volume as a function of proving time. Small differences were observed between the three methods. Free expansion shows a faster start of expansion in comparison with the two other methods. Expansion curves have been fitted with a modified Gompertz model (Romano et al., J Food Eng 83:142-148, 2007). They exhibited three phases: a lag phase, followed by a linear phase (constant expansion rate), and finally a phase with a decreasing expansion rate. Statistical analysis of the set of data showed that the proving temperature had a significant effect on the different parameters calculated (volume expansion ratio, expansion rate), while the water content had no significant effect.
A numerical simulation using Lees's three-level scheme and a fixed grid was carried out to predic... more A numerical simulation using Lees's three-level scheme and a fixed grid was carried out to predict heat and mass transfer during the freezing of a porous humid matrix. The simulations predict local moisture content, temperature and weight loss of the foods throughout the freezing process. The model accommodates the effects of temperature dependent variables such as apparent specific heat, enthalpy, thermal conductivity, and water activity. The model was validated by experiments on a cellulose sponge. The results of the model showed good agreement with experimental data.
International Journal of Pure & Applied Bioscience
The current study focused on the analysis of quality loss during freezing and thawing of Royal Ga... more The current study focused on the analysis of quality loss during freezing and thawing of Royal Gala apples under three different freezing conditions namely, freezing in a static freezer (SF) at 18oC, freezing in an air blast freezer at -40oC (IF), and freezing in an air blast freezer at -72oC (FF).The frozen samples were thawed at room temperature (20±1oC) for 2 hours prior to quality loss tests. Two types of evaluation was done namely colour and solute diffusion tests. The solute diffusion test revealed that SF samples had higher quality loss than IF and FF samples which was supported by the colour test. The ΔE values were found to be 30.39±0.23, 25.74±0.21, 24.01±0.17 for SF, IF and FF samples respectively. The browning index (BI) value of SF was found to be 100.39 which indicated a major loss in static frozen samples which coincided with the hue and chroma value. The solute diffusion test proved to be a better method in estimating the quality loss in frozen thawed Royal Gala apple samples.
The impact of pre-fermentation time and freezing rate on Sangak frozen dough and bread quality we... more The impact of pre-fermentation time and freezing rate on Sangak frozen dough and bread quality were studied. The pre-fermented doughs for 0, 30, 60, 90, or 120 min were frozen under-20,-25, or-30°C in air blast freezer. After 24 h storage at-18°C, dough samples were baked after final fermentation. The yeast viability, gassing power, and dough development for fresh and frozen Sangak doughs were determined. Crust color, density, and shear stress of bread obtained from fresh and frozen Sangak dough were evaluated. The results showed that yeast survival initially increased and then decreased with increasing freezing rate. The maximum yeast survival was observed at short pre-fermentation (30 min). A direct relationship was observed between gassing power, dough development, and yeast viability. From bread quality point-of-view, short prefermentation and higher freezing rate led to a more desirable bread.
Abstract The purpose of this study is to understand and describe the mechanisms occurring during ... more Abstract The purpose of this study is to understand and describe the mechanisms occurring during the baking of a French crepe product with a focus on the impact of the baking temperature on the formation of the “leopard” appearance. A French crepe is a very thin bakery product (ca. 0.7 mm thick), which is baked in less than 20 s at 240 °C ± 20 °C in industrial conditions. Different microscopic techniques were used to understand the impact of the process parameters on the crepe structure and the formation of the “fleur”. Crepe baking is a very rapid process during which boiling occurs at selected locations of the crepe-surface contact zone. The onset of boiling leads to the detachment of the crepe batter from the baking surface: it is related to the balance between the resistance of the batter undergoing the baking transition and the vapor pressure inside the blister formed between the baking surface and the crepe.
Chilling is a technology consisting in storing smoked salmon at-2°C/-3°C during several weeks bef... more Chilling is a technology consisting in storing smoked salmon at-2°C/-3°C during several weeks before retail displaying. This approach is an important point for controlling production and retail chain logistics. In agro-food industry, cold storage is made either at positive temperature in order to slow down the growth of bacteria or at negative temperature (freezing) in order to stop the growth of bacteria. Storing food between 0°C and the freezing point is an alternative and the results on microbial and sensorial qualities have been investigated in a research program aiming at :-highlighting determinant factors for the growth of Listeria monocytogenes (L.m): salt content, cold stiffening before slicing, kinetic characteristics of the strain, chilling duration assessing the consequences of chilling on Listeria monocytogenes growth assessing the impact of chilling on sensory changes. Results permitted to assess the impact of this technology on the final product and will help to determine the commercial shelf life of the smoked salmon. They will also contribute to collect scientific data for a Quantitative Risk Assessment (QRA).
La connaissance des phenomenes physiques survenant lors de la congelation du pain precuit permett... more La connaissance des phenomenes physiques survenant lors de la congelation du pain precuit permettrait d'apporter des elements de reponse sur l'origine de certains defauts tels que l'ecaillage, et d'optimiser le procede de fabrication. L'objectif de la these presentee ici etait de developper un modele de ces transferts, suffisamment precis pour representer l'evolution reelle des champs de temperature et de pression tout en restant simple dans ses equations. Une part importante de la these a ete consacree a la mesure et a la modelisation des proprietes thermophysiques du pain. Le modele montre, qu'en fin de congelation, la concentration en cristaux de glace est plus importante a l'interface croute/mie que dans la mie, ce qui explique en partie l'ecaillage a la cuisson finale.
Bread making is based on several simple unit operations, basically kneading, fermentation and bak... more Bread making is based on several simple unit operations, basically kneading, fermentation and baking; however, it is still a quite complex process and bread quality can be strongly affected by minor details. The market of bread production is roughly shared at 50-50 between the industry market and the artisanal market, even though the frontier between these two players is not very easy. Different strategies have been developped by the industry to extend the shelf life of bread or to interrupt the bread making process. Freezing for example has been used form the 50s to extend the shelf life of bakery products. It was first applied to fully baked products and then to frozen dough which appeared as an interesting strategy to interrupt the bread making protocol. This paper presents a review on key issues of the frozen dough technology.
Revue Generale Du Froid Du Conditionnement D Air, 2006
Apres avoir presente les differentes technologies de fabrication de pains industriels, l'arti... more Apres avoir presente les differentes technologies de fabrication de pains industriels, l'article expose les travaux realises a l'ENITIAA sur l'ecaillage de la croute. Il met en evidence l'importance des procedes de fabrication afin de limiter ce phenomene.
This paper proposes an original study on the impact of the process condition using pre-fermented ... more This paper proposes an original study on the impact of the process condition using pre-fermented frozen dough on the final bread volume. The impact of the degree of pre-fermentation before freezing and the impact of the freezing conditions have been considered with an experimental design procedure. The first fermentation step (prefermentation) was between 60 and 120 min and the corresponding second (or final) fermentation was between 60 and 0 min, respectively, resulting in a total fermentation time of 120 min. Freezing was performed between the first and the second fermentation at −20°C, −30°C or −40°C in blast air tunnel. The results show that the faster the freezing rate, the higher the final bread volume. Further work is needed to fully optimise this process, which is minimally present at the industrial bread market, whereas the technology is now adopted by many viennoiseries such as croissant and laminated puffing pastries.
In this study, a novel experimental setup was developed and an innovative process was implemented... more In this study, a novel experimental setup was developed and an innovative process was implemented aiming at the application of microwave radiation during freezing of a food matrix. The results acquired from the present study are considered as remarkable and promising. The developed freezing process was applied on pork tenderloin samples. The application of microwaves during cooling the samples caused oscillated decrease of temperature and had a significant impact on the crystallization process as the degree of supercooling was decreased circa 92% under the tested conditions. The meat microstructure evaluation showed a 62% decrease in the average ice crystal size when samples were frozen under a microwave field as compared to the conventional freezing process. These results indicate that the application of microwave radiation during freezing may reduce the damage of the meat tissue and in turn to retain better texture in the frozen meat.
International Journal of Pure & Applied Bioscience, 2019
Appearance is one of the sensory attributes that give first impression regarding a product to the... more Appearance is one of the sensory attributes that give first impression regarding a product to the consumers. Color plays a major role in determining the overall quality of the product. Acidic cakes like lemon cakes are unique in taste and flavor. In this study, changes in color of cakes were analyzed and the effect of pH and sugar on color was evaluated. Cakes were baked at similar processing conditions. Lemon juice and maltitol were added in different proportions by varying water and sucrose respectively with other ingredients. Color of crust and crumb were evaluated on the second day of baking using colorimeter. A significant color difference was observed between samples. Crust color become darker and color intensity of crumb increased on increasing the amount of lemon juice. Reducing sugars produced due to acid hydrolysis of sucrose promotes browning. Maltitol didn’t contribute significantly to the browning reaction.
International Journal of Pure & Applied Bioscience, 2019
Experiments were carried out to study the impact of pressure change during dough mixing with a sp... more Experiments were carried out to study the impact of pressure change during dough mixing with a spiral dough mixer with the possibility of controlling the temperature. Three pressure and spiral tool speed conditions were used in this experiment: 50, 250 and 500 mbar and 100,150 and 200 RPM respectively. The objectives were to understand the effect of pressure and tool speed on dough during kneading in order to optimize dough kneading conditions. The results showed that dough aeration was proportional to the number of rotations of the spiral tool. Higher pressure and higher-speed mixing reduced the time to reach maximum power (tPEAK) means duration of mixing can be reduced. Bread specific volume, porosity fraction and pore size distributions were analysed for a better understanding of the impact of high pressure on bread quality.
La congelation est un procede largement utilise dans les industries agro-alimentaires. La surgela... more La congelation est un procede largement utilise dans les industries agro-alimentaires. La surgelation est un mot qui a ete cree dans les annees 1970 afin d'ameliorer la reconnaissance des produits congeles de qualite superieure ; ce terme a ete defini par un arrete. Il a ete conserve dans les nouveaux arretes issus des directives europeennes. Cependant, l'interpretation de ces arretes et la notion de produit « congele » ou « non congele » reste tres imprecise dans le cas de produits alimentaires complexes et heterogenes; en effet, la cristallisation de l'eau se fait sur une plage de temperature large. L'interpretation proposee s'appuie sur un texte de l'IIF (livre rouge) proposant qu'un produit peut etre considere comme congele lorsque 80 % de son eau est congelee. Une etude de cas realisee sur un produit de type quiche est presentee et montre l'interet de l'approche proposee.
The aim of this work was to investigate different methods of measuring the expansion of bread dou... more The aim of this work was to investigate different methods of measuring the expansion of bread dough during fermentation and to develop a mathematical model to describe the variation of dough volume. Dough was prepared with wheat flour, salt, yeast, and selected amount of water (56%, 58%, and 60% w/w flour basis). Proving time was 1 h and proving temperature investigated were 25, 30, and 35°C. Dough volume was measured with three methods: (1) vertical expansion in a flask, (2) horizontal expansion between two plates, and (3) free expansion method. Volume was measured either using displacement transducer or from image analysis of pictures taken during expansion. All the methods allowed monitoring the increase in dough volume as a function of proving time. Small differences were observed between the three methods. Free expansion shows a faster start of expansion in comparison with the two other methods. Expansion curves have been fitted with a modified Gompertz model (Romano et al., J Food Eng 83:142-148, 2007). They exhibited three phases: a lag phase, followed by a linear phase (constant expansion rate), and finally a phase with a decreasing expansion rate. Statistical analysis of the set of data showed that the proving temperature had a significant effect on the different parameters calculated (volume expansion ratio, expansion rate), while the water content had no significant effect.
A numerical simulation using Lees's three-level scheme and a fixed grid was carried out to predic... more A numerical simulation using Lees's three-level scheme and a fixed grid was carried out to predict heat and mass transfer during the freezing of a porous humid matrix. The simulations predict local moisture content, temperature and weight loss of the foods throughout the freezing process. The model accommodates the effects of temperature dependent variables such as apparent specific heat, enthalpy, thermal conductivity, and water activity. The model was validated by experiments on a cellulose sponge. The results of the model showed good agreement with experimental data.
International Journal of Pure & Applied Bioscience
The current study focused on the analysis of quality loss during freezing and thawing of Royal Ga... more The current study focused on the analysis of quality loss during freezing and thawing of Royal Gala apples under three different freezing conditions namely, freezing in a static freezer (SF) at 18oC, freezing in an air blast freezer at -40oC (IF), and freezing in an air blast freezer at -72oC (FF).The frozen samples were thawed at room temperature (20±1oC) for 2 hours prior to quality loss tests. Two types of evaluation was done namely colour and solute diffusion tests. The solute diffusion test revealed that SF samples had higher quality loss than IF and FF samples which was supported by the colour test. The ΔE values were found to be 30.39±0.23, 25.74±0.21, 24.01±0.17 for SF, IF and FF samples respectively. The browning index (BI) value of SF was found to be 100.39 which indicated a major loss in static frozen samples which coincided with the hue and chroma value. The solute diffusion test proved to be a better method in estimating the quality loss in frozen thawed Royal Gala apple samples.
The impact of pre-fermentation time and freezing rate on Sangak frozen dough and bread quality we... more The impact of pre-fermentation time and freezing rate on Sangak frozen dough and bread quality were studied. The pre-fermented doughs for 0, 30, 60, 90, or 120 min were frozen under-20,-25, or-30°C in air blast freezer. After 24 h storage at-18°C, dough samples were baked after final fermentation. The yeast viability, gassing power, and dough development for fresh and frozen Sangak doughs were determined. Crust color, density, and shear stress of bread obtained from fresh and frozen Sangak dough were evaluated. The results showed that yeast survival initially increased and then decreased with increasing freezing rate. The maximum yeast survival was observed at short pre-fermentation (30 min). A direct relationship was observed between gassing power, dough development, and yeast viability. From bread quality point-of-view, short prefermentation and higher freezing rate led to a more desirable bread.
Abstract The purpose of this study is to understand and describe the mechanisms occurring during ... more Abstract The purpose of this study is to understand and describe the mechanisms occurring during the baking of a French crepe product with a focus on the impact of the baking temperature on the formation of the “leopard” appearance. A French crepe is a very thin bakery product (ca. 0.7 mm thick), which is baked in less than 20 s at 240 °C ± 20 °C in industrial conditions. Different microscopic techniques were used to understand the impact of the process parameters on the crepe structure and the formation of the “fleur”. Crepe baking is a very rapid process during which boiling occurs at selected locations of the crepe-surface contact zone. The onset of boiling leads to the detachment of the crepe batter from the baking surface: it is related to the balance between the resistance of the batter undergoing the baking transition and the vapor pressure inside the blister formed between the baking surface and the crepe.
Chilling is a technology consisting in storing smoked salmon at-2°C/-3°C during several weeks bef... more Chilling is a technology consisting in storing smoked salmon at-2°C/-3°C during several weeks before retail displaying. This approach is an important point for controlling production and retail chain logistics. In agro-food industry, cold storage is made either at positive temperature in order to slow down the growth of bacteria or at negative temperature (freezing) in order to stop the growth of bacteria. Storing food between 0°C and the freezing point is an alternative and the results on microbial and sensorial qualities have been investigated in a research program aiming at :-highlighting determinant factors for the growth of Listeria monocytogenes (L.m): salt content, cold stiffening before slicing, kinetic characteristics of the strain, chilling duration assessing the consequences of chilling on Listeria monocytogenes growth assessing the impact of chilling on sensory changes. Results permitted to assess the impact of this technology on the final product and will help to determine the commercial shelf life of the smoked salmon. They will also contribute to collect scientific data for a Quantitative Risk Assessment (QRA).
La connaissance des phenomenes physiques survenant lors de la congelation du pain precuit permett... more La connaissance des phenomenes physiques survenant lors de la congelation du pain precuit permettrait d'apporter des elements de reponse sur l'origine de certains defauts tels que l'ecaillage, et d'optimiser le procede de fabrication. L'objectif de la these presentee ici etait de developper un modele de ces transferts, suffisamment precis pour representer l'evolution reelle des champs de temperature et de pression tout en restant simple dans ses equations. Une part importante de la these a ete consacree a la mesure et a la modelisation des proprietes thermophysiques du pain. Le modele montre, qu'en fin de congelation, la concentration en cristaux de glace est plus importante a l'interface croute/mie que dans la mie, ce qui explique en partie l'ecaillage a la cuisson finale.
Bread making is based on several simple unit operations, basically kneading, fermentation and bak... more Bread making is based on several simple unit operations, basically kneading, fermentation and baking; however, it is still a quite complex process and bread quality can be strongly affected by minor details. The market of bread production is roughly shared at 50-50 between the industry market and the artisanal market, even though the frontier between these two players is not very easy. Different strategies have been developped by the industry to extend the shelf life of bread or to interrupt the bread making process. Freezing for example has been used form the 50s to extend the shelf life of bakery products. It was first applied to fully baked products and then to frozen dough which appeared as an interesting strategy to interrupt the bread making protocol. This paper presents a review on key issues of the frozen dough technology.
Revue Generale Du Froid Du Conditionnement D Air, 2006
Apres avoir presente les differentes technologies de fabrication de pains industriels, l'arti... more Apres avoir presente les differentes technologies de fabrication de pains industriels, l'article expose les travaux realises a l'ENITIAA sur l'ecaillage de la croute. Il met en evidence l'importance des procedes de fabrication afin de limiter ce phenomene.
This paper proposes an original study on the impact of the process condition using pre-fermented ... more This paper proposes an original study on the impact of the process condition using pre-fermented frozen dough on the final bread volume. The impact of the degree of pre-fermentation before freezing and the impact of the freezing conditions have been considered with an experimental design procedure. The first fermentation step (prefermentation) was between 60 and 120 min and the corresponding second (or final) fermentation was between 60 and 0 min, respectively, resulting in a total fermentation time of 120 min. Freezing was performed between the first and the second fermentation at −20°C, −30°C or −40°C in blast air tunnel. The results show that the faster the freezing rate, the higher the final bread volume. Further work is needed to fully optimise this process, which is minimally present at the industrial bread market, whereas the technology is now adopted by many viennoiseries such as croissant and laminated puffing pastries.
In this study, a novel experimental setup was developed and an innovative process was implemented... more In this study, a novel experimental setup was developed and an innovative process was implemented aiming at the application of microwave radiation during freezing of a food matrix. The results acquired from the present study are considered as remarkable and promising. The developed freezing process was applied on pork tenderloin samples. The application of microwaves during cooling the samples caused oscillated decrease of temperature and had a significant impact on the crystallization process as the degree of supercooling was decreased circa 92% under the tested conditions. The meat microstructure evaluation showed a 62% decrease in the average ice crystal size when samples were frozen under a microwave field as compared to the conventional freezing process. These results indicate that the application of microwave radiation during freezing may reduce the damage of the meat tissue and in turn to retain better texture in the frozen meat.
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