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Background Results Conclusion The sorption characteristics and glass transition temperature are important attributes that determine the shelf life of foods, particularly in powder form, whereas color is a key factor influencing consumer acceptance. As the popularity of matcha green tea powder is increasing, this study investigated whether the country of origin of examples of matcha products available on the Polish market influenced the sorption properties, glass transition temperature, and color.All matcha powders exhibited sigmoidal water adsorption isotherms at 25 °C. The monolayer moisture content corresponding to the point of maximum stability ranged from 0.045 to 0.053 g water per g of sample. The glass transition temperature of anhydrous matcha powders varied between 106.3 and 139.0 °C. Based on the sorption and glass transition results, the matcha from Brazil should be the most stable during storage. The same sample showed the highest water solubility index values at temperatures above 80 °C and the lowest bulk density. The color parameters (L*, a*, b*, C*, and h) depended on the matcha powder variant.The results indicate that the optimal storage conditions for tea powders do not depend directly on the country of origin. Further research should therefore focus on analyzing the impact of climate or fertilization. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Maltodextrins are extensively used in the food industry to shape the physicochemical properties of food products. This multiscale study investigates three different Dextrose Equivalent (DE) maltodextrins as model matrices to elucidate the relationship between techno-functional behaviors and single particle surface properties. It was evidenced that environmental variations and glass transition influence single particle properties, significantly impacting the powder bulk behavior. Utilizing Confocal Laser Scanning Microscopy (CLSM) and environmental Atomic Force Microscopy (AFM) at the single particle level, correlations between the wetting and nanomechanical properties of all maltodextrins were provided. It was revealed that wetting properties are directly DE dependent, as higher DE maltodextrins had shorter wetting times. Moreover, glass transition plays a critical role in determining surface elasticity and capillary adhesion, as it alters both physicochemical properties and particle morphology. Indeed, a decrease of the Young modulus with Relative Humidity (RH) and glass transition correlated with the increase of capillary forces. This was corroborated by Scanning Electron Microscopy (SEM) and Specific Surface Area (SSA) measurements at different RH. These findings confirmed that glass transition drives particle morphology, with global surface smoothing and swelling occurring in the rubbery state. [Display omitted] • Environmental AFM was used to probe Young modulus and capillary adhesion evolution. • SEM was used to follow particle morphology evolution over RH and glass transition. • Reconstitution kinetics of single maltodextrins particle were studied by CLSM. • Specific surface area of maltodextrins was proved to be DE and Tg dependent. [ABSTRACT FROM AUTHOR]

For the first time on food powders, environmental Atomic Force Microscopy (AFM) was used to probe single particle surface properties in real time by variating relative humidity (RH) and temperature. Low, intermediate, and high dextrose equivalent (DE) maltodextrins values were used as a model matrix. Humidity ramps from 20 to 80% at constant temperatures of 20 and 50 °C and temperature ramps from 20 to 50 °C at a constant RH of 20 and 80% were performed. Surface topography, roughness, and Young modulus distribution evolutions at the particle surface were studied under these conditions. It was observed that glass transition and RH are driving particle surface properties. Glass transition was always accompanied by a significant global surface smoothing, whatever the DE value. Surface smoothing phenomenon were also accompanied by a large decrease of the surface roughness with the increase of RH. Apart from the impact on surface topography, glass transition also impacted particle physics. Particles in the glassy state were relatively hard with a high and heterogenous Young modulus distribution. An increase in the RH made the particle progressively softer, whereas crossing the glass transition temperature leads to a really soft surface and to the homogenization of the Young modulus distribution. These results showed that glass transition significantly impacts particle surface properties and is promising to optimize food powder formulation and their shelf-life extension. [Display omitted] • Environmental AFM was used to probe single maltodextrins particles properties in real time. • AFM surface topographies revealed surface smoothing phenomenon with glass transition. • Young modulus decreases significantly and its distribution is homogenized with glass transition. [ABSTRACT FROM AUTHOR]

Out of total honey production in Poland, only 1% is used on an industrial scale.Limited use of honey is related to its sticky consistency, which causes problems with cleaningthe devices, and crystallization, which makes it necessary to re-liquefaction. Honey powderseems to be a perfect solution for the problem. Unfortunately, it is not easy to obtain honey inpowder. Due to high content of sugar in honey (in the amount of 80%) it has a low glasstransition temperature, which leads to the formation of gum structure, which makes the dryingdifficult. The use of carrier substances increases the glass transition temperature and allows toobtain honey powder. The production of honey powder with good functional properties, smallcontent of drying additions and little loss of biologically active compounds is still technicaland technological challenge for the researchers. [ABSTRACT FROM AUTHOR]

Abstract: This work examined and compared the caking behaviour of three physically and chemically different food powders. The food powders studied were maltodextrin DE21 which is an amorphous powder, common salt which consists of crystalline NaCl, and skim milk powder (SMP) which contains a mixture of components including 51% lactose. The three powders were all exposed to high relative humidities (76% or 100%) over a 1-week period and to a humidity cycle to investigate their caking behaviour and interpret their caking mechanisms. The humidity cycle consisted of 2-day exposure to a high relative humidity (RH) followed by 2-day exposure to low RH of 11% and finally 2-day exposure to the original high RH. At the end of each day, cake strength was measured using a force displacement tester and cake water content was also measured. All three powders sorbed much water when exposed to high relative humidities; however, their cake strengths were very different. Cake strength was influenced by glass transition and the ability of the powders to form sinter bridges. All three powders had similar water content profiles during the humidity cycle with water gain at high RH and loss at low RH. The cake strength profile of the amorphous maltodextrin powder and amorphous SMP were different even though the maltodextrin and lactose glass transition temperatures were reduced below the powder temperature during exposure to high RH. The cake strength of maltodextrin decreased during low RH exposure while it increased for SMP. The cake strength profile of the SMP was similar to the crystalline NaCl. The paper presents an interpretation of the caking mechanisms behind the caking behaviour of each powder. [Copyright &y& Elsevier]

Abstract: A cyclone stickiness test device from a preliminary work was modified and used for characterizing stickiness behaviour of food powders. This test device employed the principle of particle dynamics in cyclone section of a spray dryer. The device was more compacted and consisted of temperature–humidity controlled air generator and cyclone test chamber. Characteristic temperature–humidity curves were determined and served as the maximum test conditions. Skim milk powder was used as a model for stickiness testing. The sample was subjected to various air conditions in the cyclone and stickiness conditions were determined. Surface moisture content and glass transition temperature at sticky point were also analysed. It was found that as the particle surface temperature increased humidity at which stickiness occurred decreased. Stickiness curve was drawn to separate between sticky and non-sticky conditions. The curve of glass transition temperature vs equilibrium surface moisture content at sticky points was obtained. It was found that the sticky curve laid at 11.4°C above the glass transition temperature line. [Copyright &y& Elsevier]

Particle properties can have a major influence on the design and optimisation of particle production, handling and processing operations. This paper provides a selected number of examples of how particle properties influence the design and optimisation of food particle operations. These include the influence of particle size and how particle breakage influences size during precipitationcrystallization processes and subsequent transport and particle separation; powder flow out of hoppers and silos; and the influence of glass transition on particle stickiness and how this affects the performance of a number of operations. [ABSTRACT FROM AUTHOR]

Abstract: Many powders contain amorphous components, such as amorphous lactose in milk powders, which when given sufficient conditions of temperature and water content, will mobilise as a high viscosity flow making the particles sticky. This can lead to increased cohesiveness, powder caking and increased adhesion to surfaces. The transition from the glassy state is established by increasing the powder temperature to above its glass transition temperature which can be measured using differential scanning calorimetry. Exposing milk powder to over 10–20 °C above the lactose glass transition makes the powder more sticky, rendering it a lot more cohesive and also increases its adhesion to a stainless steel surface. This glass transition induced stickiness is time-dependent. Over time, crystallisation can take place converting the amorphous lactose into crystalline lactose. Furthermore, the caking behaviour of powders depends on the amount of component present in the amorphous state. Finally, this work presents an approach for applying the measured relationship between the glass transition and water content for predicting caking problems with powders containing amorphous components. [Copyright &y& Elsevier]

A new Thermal Mechanical Compression Test (TMCT) was applied for glass-rubber transition and melting analyses of food powders and crystals. The TMCT technique measures the phase change of a material based on mechanical changes during the transition. Whey, honey, and apple juice powders were analyzed for their glass-rubber transition temperatures. Sucrose and glucose monohydrate crystals were analyzed for their melting temperatures. The results were compared to the values obtained by conventional DSC and TMA techniques. The new TMCT technique provided the results that were very close to the conventional techniques. This technique can be an alternative to analyze glass-rubber transition of food, pharmaceutical, and chemical dry products. [ABSTRACT FROM AUTHOR]

The state diagrams of freeze-dried pumpkin powders with different maltodextrin additions were developed using glass transition line, freezing curve and maximal-freeze-concentrations conditions. The freezing curve was plotted employing Clausius – Clapeyron equation and glass transition lines were developed using Gordon – Taylor model. The ultimate maximum-freeze-concentration conditions of the powders were observed in range from 0.685 to 0.745 g solids/g sample. Characteristic glass transition temperature of maximum-freeze-concentration (Tg') of the pumpkin was equal to - 83.7 °C and was increase with increasing maltodextrin addition. Adsorption isotherms of pumpkin – maltodextrin powders were determined at 25 °C by static - gravimetric method and the experimental data was modelled with BET and GAB equations. Monolayer moisture content of the pumpkin powder decreased with increasing maltodextrin additions. The state diagram and water adsorption isotherms of the pumpkin – maltodextrin powders are useful for predicting suitable storage and processing conditions. • Isotherm of pumpkin powder was "J-shape" while curves of the blends were sigmoidal. • Pure materials showed higher monolayer moisture content than their blends. • Glass transition temperature values increased with growing maltodextrin additions. • Maximally-freeze-concentrated parameters values dependent on polymer content. • State diagrams are useful in predicting shelf life of food powders. [ABSTRACT FROM AUTHOR]