- Athens, Greece
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Abstract Jet milling is an emerging, size reduction technique for producing superfine powders in one-step process. The aim of the present article was the research about the efficiency of jet milling process on the wheat flour... more
Abstract Jet milling is an emerging, size reduction technique for producing superfine powders in one-step process. The aim of the present article was the research about the efficiency of jet milling process on the wheat flour micronization. A mathematical power model is proposed to describe the effect of feed rate and air pressure on the final flour particle size and energy consumption. A sample of soft wheat flour was grοund using a jet mill at different feed rate (FR) and air pressure (AP) (2-18 kg/h at 4 and 8 bar, respectively). Τhe decrease in FR and further increase in AP resulted in finer flour reaching the lowest value of 10.62 μm. The energy-size reduction equations revealed that the particle size, as well as the energy consumption, were mainly influenced by FR and to a lower extent by AP. FR of 70 % was the limit for energy efficient grinding. Α short grinding at high FR and AP is also preferable as damaged starch content was lower.
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Abstract Physical properties of foods are inevitably involved in food-processing operations, giving useful information on how to handle a raw material and they affect how food will be processed, stored, and consumed. They include thermal,... more
Abstract Physical properties of foods are inevitably involved in food-processing operations, giving useful information on how to handle a raw material and they affect how food will be processed, stored, and consumed. They include thermal, mass, structural, optical, rheological, electrical, and acoustic properties. This chapter covers only some key issues of physical properties of food defining terms and methods. Particle characterization using geometric properties such as size and shape is of great importance for food processing and quality evaluation. Density and porosity terminology are clearly defined to facilitate the understanding of how and when they are used. Mechanical properties and texture of solids are described. Moreover, the texture profile analysis (TPA) technique and the effect of time on a viscoelastic material are presented. The last part of this chapter presents the means of food color evaluation and reviews the color parameters that were evaluated during dry process. Some case studies are presented in the chapter to demonstrate the importance of determining physical properties of food in the food industry.
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Σκοπός της παρούσας διατριβής ήταν η μελέτη της επίδρασης της άλεσης με jet mill στα φυσικοχημικά χαρακτηριστικά αλεύρων σίτου και η αξιολόγηση της δυνατότητας ενσωμάτωσης των κονιορτοποιημένων αλεύρων σε άρτους και μπισκότα. Αρχικά έγινε... more
Σκοπός της παρούσας διατριβής ήταν η μελέτη της επίδρασης της άλεσης με jet mill στα φυσικοχημικά χαρακτηριστικά αλεύρων σίτου και η αξιολόγηση της δυνατότητας ενσωμάτωσης των κονιορτοποιημένων αλεύρων σε άρτους και μπισκότα. Αρχικά έγινε σύγκριση της παραδοσιακής άλεσης με την άλεση με πεπιεσμένο αέρα (jet mill). Χρησιμοποιήθηκαν τρία κλάσματα μαλακού αλεύρου σίτου τύπου Τ70 από κυλινδρόμυλο: ένα χονδρόκοκκο, ένα ενδιάμεσο και ένα λεπτόκοκκο κλάσμα άλεσης. Στη συνέχεια πραγματοποιήθηκε αξιολόγηση της επίδρασης της άλεσης με jet mill σε Τ70 και ανάπτυξη μαθηματικών μοντέλων για την κοκκομετρία του αλεύρου και την κατανάλωση ενέργειας. Αύξηση της έντασης της διεργασίας (μικρός ρυθμός τροφοδοσίας πρώτης ύλης, υψηλή πίεση αέρα ή/και ανατροφοδότηση) είχε ως αποτέλεσμα την παραγωγή αλεύρων με μικρότερη κοκκομετρία και υγρασία, μεγαλύτερο ποσοστό κατεστραμμένου αμύλου και αύξηση της απορρόφησης. Λαμβάνοντας υπόψιν τα παραπάνω επιλέχτηκαν τέσσερις συνδυασμοί άλεσης (κατανάλωση ενέργειας κα...
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Abstract Cactus (Opuntia ficus-indica) cladodes are a source of dietary fiber, vitamins and antioxidants that could be utilized by the food industry for both their nutritional and technological properties. In the present study, cladodes... more
Abstract Cactus (Opuntia ficus-indica) cladodes are a source of dietary fiber, vitamins and antioxidants that could be utilized by the food industry for both their nutritional and technological properties. In the present study, cladodes were dried at 45°C for 24 h, followed by a 18 h vacuum drying at 45°C or 60°C. The dried cladodes were then ground in a grain mill, resulting in two coarse cladode flours (C45 and C60, respectively). A portion of the two flours was further ground with jet mill, yielding two fine flours, J45 and J60, respectively. Color, bulk density, water and oil holding capacities, solubility and dietary fiber content were determined. In addition, rheological properties and sedimentation kinetic of aqueous cladode flour suspensions were evaluated. An increase of insoluble fiber was observed with micro-grinding. All samples exhibited shear thinning behavior, while jet milling led to substantial decrease in apparent viscosity values. Coarse fractions sedimented quickly, achieving almost maximum sedimentation within 10 min, while the micro ground samples sedimented half as fast. In conclusion, particle size significantly alters the technological properties of cladode flour, broadening the range of applications cladodes could be used for.
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Finer barley and rye flours were produced by jet milling at two feed rates. The effect of reduced particle size on composition and several physicochemical and mechanical properties of all flours were evaluated. Moisture content decreased... more
Finer barley and rye flours were produced by jet milling at two feed rates. The effect of reduced particle size on composition and several physicochemical and mechanical properties of all flours were evaluated. Moisture content decreased as the size of the granules decreased. Differences on ash and protein contents were observed. Jet milling increased the amount of damaged starch in both rye and barley flours. True density increased with decreased particle size whereas porosity and bulk density increased. The solvent retention capacity profile was also affected by jet milling. Barley was richer in phenolics and had greater antioxidant activity than rye. Regarding colour, both rye and barley flours when subjected to jet milling became brighter, whereas their yellowness was not altered significantly. The minimum gelation concentration for all flours was 16%w/v. Barley flour gels were stronger, firmer and more elastic than the rye ones.
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Dietary fibres can play a significant role in GF bread development. Besides their well documented health benefits, dietary fibres can improve the texture, sensory characteristics and shelf life of baked products, due to their water... more
Dietary fibres can play a significant role in GF bread development. Besides their well documented health benefits, dietary fibres can improve the texture, sensory characteristics and shelf life of baked products, due to their water binding capacity, gel forming ability, fat mimetic, textural and thickening effects. Dietary fibres from different sources are discussed in this paper and their role in GF products' making is analysed. The sources of fibres vary: flours, fruit and vegetable processing by-products, isolated ingredients, seeds or mixtures of all of these can be used. Fibres improve the structure and result in dense crumb porosity. Tasty products with soft crumb can be produced, and there are many perspectives in further products development.
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ABSTRACT Stabilizers are widely used in low-fat emulsion production. However, food industry pays attention to ingredients, such as resistant starch (RS) that also present substantial benefits to human health. Low-fat model emulsions of... more
ABSTRACT Stabilizers are widely used in low-fat emulsion production. However, food industry pays attention to ingredients, such as resistant starch (RS) that also present substantial benefits to human health. Low-fat model emulsions of either olive or sesame oil that also contained xanthan gum (XG), whey protein concentrate (WPC), and undigested (resistant) starch (RS) were produced and stored at 5 °C. Salt was added in selected samples. A multiple light scattering technique was applied for investigating destabilization phenomena. Microscopic observations and droplet size measurements took place. Rheological properties performing a heating–cooling cycle experiment (5–25–5 °C) were measured. Olive oil emulsions presented the greatest stability and the lowest droplet size. RS plays the role of solid particle stabilizer, mainly entrapped in the matrix of the continuous phase. By salt addition stability was significantly improved, whereas droplet size was decreased. Those samples had a more pronounced elastic character and significantly greater viscosity values than their counterparts without salt.
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ABSTRACT The objectives of this research were to substitute (10–50%) sucrose with fructooligosaccharides (FOS) in cream caramel dessert and to study the rheological and sensory characteristics of the gels produced. Small deformation... more
ABSTRACT The objectives of this research were to substitute (10–50%) sucrose with fructooligosaccharides (FOS) in cream caramel dessert and to study the rheological and sensory characteristics of the gels produced. Small deformation experiments showed that the substitution of sucrose with FOS led to a decrease in the solid character of the gels. Moreover, samples in which sucrose was substituted with 20% and 30% FOS exhibited lower gel strength, and sample containing 30% FOS showed more than three times lower gel strength than that with 100% sucrose. However, all samples, albeit fluids, already had a substantial gel‐like character at high temperature. According to large deformation experiments, the strength and rigidity of all samples increased with storage time. The values for both parameters were greater for the samples containing 100% and 90% sucrose. Triangle tests were performed for sensory evaluation. Panellists did not find significant differences in terms of sweetness when sucrose was substituted up to 30%. Storage was significant only for the sample with 100% sucrose, as the sensory characteristics of the sample with 10% FOS were not affected.
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The aim of this study was to evaluate the potential use of micronized whole wheat flours in breadmaking. The micronization process was achieved by a jet mill and flours (JF) of particle size, ranged from 17 to 84 μm, were used. According... more
The aim of this study was to evaluate the potential use of micronized whole wheat flours in breadmaking. The micronization process was achieved by a jet mill and flours (JF) of particle size, ranged from 17 to 84 μm, were used. According to the particle size of the JF, the amount of water added to dough changed and ranged from 77 to 84% as it was calculated in farinograph experiments. JF breads had higher bread yield, firmer crumb, higher elasticity, lower porosity and darker bread color compared to control whole wheat bread. Overall a lower particle size of JF resulted in a close structure of bread. According to sensory evaluation, difference among samples was difficult to perceive. During storage JF bread presented lower limiting firmness potential. After all, there is evidence that jet milled flour determined bread physical characteristics and further storage stability.
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Cactus (Opuntia ficus-indica) cladodes are a source of dietary fiber, vitamins and antioxidants that could be utilized by the food industry for both their nutritional and technological properties. In the present study, cladodes were dried... more
Cactus (Opuntia ficus-indica) cladodes are a source of dietary fiber, vitamins and antioxidants that could be utilized by the food industry for both their nutritional and technological properties. In the present study, cladodes were dried at 45 • C for 24 h, followed by a 18 h vacuum drying at 45 • C or 60 • C. The dried cladodes were then ground in a grain mill, resulting in two coarse cladode flours (C45 and C60, respectively). A portion of the two flours was further ground with jet mill, yielding two fine flours, J45 and J60, respectively. Color, bulk density, water and oil holding capacities, solubility and dietary fiber content were determined. In addition, rheological properties and sedimentation kinetic of aqueous cladode flour suspensions were evaluated. An increase of insoluble fiber was observed with micro-grinding. All samples exhibited shear thinning behavior, while jet milling led to substantial decrease in apparent viscosity values. Coarse fractions sedimented quickly,...
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The particle size of wheat flour has a significant effect on its functional properties. Three fractions of roller milled wheat flour were obtained using sieving: a coarse fraction (CF) with d50 > 200 μm, a middle fraction (MF) with 100... more
The particle size of wheat flour has a significant effect on its functional properties. Three fractions of roller
milled wheat flour were obtained using sieving: a coarse fraction (CF) with d50 > 200 μm, a middle fraction
(MF) with 100 μm< d50 < 200 lm and a fine fraction (FF) with d50 < 100 μm. An extra fine fraction
was received by pulverizing CF in a jet mill (JCF). Particle size volume distributions were determined
and further samples characterisation included: chemical composition, water holding capacity (WHC),
starch damage, swelling capacity, and slurries viscoelasticity. CF presented bimodal granules’ volume distribution
containing many agglomerates of irregular shape. The fine fractions differed significantly. JCF
contained spherical granules, whereas FF irregular granules’ fragments with a few free starch granules.
JCF presented the highest WHC and granules swelled fast (up to 75 οC) with a great soluble solids leakage.
FF presented a delayed gelatinisation and low elasticity, indicating a weak structure.
milled wheat flour were obtained using sieving: a coarse fraction (CF) with d50 > 200 μm, a middle fraction
(MF) with 100 μm< d50 < 200 lm and a fine fraction (FF) with d50 < 100 μm. An extra fine fraction
was received by pulverizing CF in a jet mill (JCF). Particle size volume distributions were determined
and further samples characterisation included: chemical composition, water holding capacity (WHC),
starch damage, swelling capacity, and slurries viscoelasticity. CF presented bimodal granules’ volume distribution
containing many agglomerates of irregular shape. The fine fractions differed significantly. JCF
contained spherical granules, whereas FF irregular granules’ fragments with a few free starch granules.
JCF presented the highest WHC and granules swelled fast (up to 75 οC) with a great soluble solids leakage.
FF presented a delayed gelatinisation and low elasticity, indicating a weak structure.
The objectives of this research were to substitute (10–50%) sucrose with fructooligosaccharides (FOS) in cream caramel dessert and to study the rheological and sensory characteristics of the gels produced. Small deformation experiments... more
The objectives of this research were to substitute (10–50%) sucrose with fructooligosaccharides (FOS) in cream caramel dessert and to study the rheological and sensory characteristics of the gels produced. Small deformation experiments showed that the substitution of sucrose with FOS led to a decrease in the solid character of the gels. Moreover, samples in which sucrose was substituted with 20% and 30% FOS exhibited lower gel strength, and sample containing 30% FOS showed more than three times lower gel strength than that with 100% sucrose. However, all samples, albeit fluids, already had a substantial gel-like character at high temperature. According to large deformation experiments, the strength and rigidity of all samples increased with storage time. The values for both parameters were greater for the samples containing 100% and 90% sucrose. Triangle tests were performed for sensory evaluation. Panellists did not find significant differences in terms of sweetness when sucrose was substituted up to 30%. Storage was significant only for the sample with 100% sucrose, as the sensory characteristics of the sample with 10% FOS were not affected.
Research Interests:
Stabilizers are widely used in low-fat emulsion production. However, food industry pays attention to ingredients, such as resistant starch (RS) that also present substantial benefits to human health. Low-fat model emulsions of either... more
Stabilizers are widely used in low-fat emulsion production. However, food industry pays attention to ingredients, such as resistant starch (RS) that also present substantial benefits to human health. Low-fat model emulsions of either olive or sesame oil that also contained xanthan gum (XG), whey protein concentrate (WPC), and undigested (resistant) starch (RS) were produced and stored at 5 °C. Salt was added in selected samples. A multiple light scattering technique was applied for investigating destabilization phenomena. Microscopic observations and droplet size measurements took place. Rheological properties performing a heating–cooling cycle experiment (5–25–5 °C) were measured. Olive oil emulsions presented the greatest stability and the lowest droplet size. RS plays the role of solid particle stabilizer, mainly entrapped in the matrix of the continuous phase. By salt addition stability was significantly improved, whereas droplet size was decreased. Those samples had a more pronounced elastic character and significantly greater viscosity values than their counterparts without salt.