Oligosaccharide, sucrose, and allulose effects on the pasting and retrogradation behaviors of wheat starch.

The pasting and retrogradation behaviors of starch are altered by the presence of sugars and are important in dictating the storage stability and texture of starch-containing foods. The use of oligosaccharides (OS) and allulose in reduced-sugar formulations is being explored. The objectives of this study were to determine the impacts of different types and concentrations (0% to 60% w/w) of OS (fructo-OS, gluco-OS, isomalto-OS, gluco-dextrin, and xylo-OS) and allulose on the pasting and retrogradation attributes of wheat starch compared to starch in water (control) or sucrose solutions using DSC and rheometry. Physicochemical properties of the additives and their effects on amylose leaching were also considered. Significant differences in starch pasting, retrogradation, and amylose leaching were found between the control and additive solutions, influenced by additive type and concentration. Allulose increased starch paste viscosity and promoted retrogradation over time (60% conc. PV = 7628 cP; ΔHret, 14 = 3.18 J/g) compared to the control (PV = 1473 cP; ΔHret, 14 = 2.66 J/g) and all OS (PV = 14 to 1834 cP; ΔHret,14 = 0.34 to 3.08 J/g). In the allulose, sucrose, and xylo-OS solutions, compared to the other OS types, the gelatinization and pasting temperatures of starch were lower, more amylose leaching occurred, and pasting viscosities were higher. Increasing OS concentrations elevated gelatinization and pasting temperatures. In most 60% OS solutions these temperatures exceeded 95 °C thereby preventing starch gelatinization and pasting in the rheological analysis, and in conditions relevant for inhibiting starch gelatinization in low moisture-sweetened products. Fructose-analog additives (allulose and fructo-OS) promoted starch retrogradation more than the other additives, while xylo-OS was the only additive that limited retrogradation across all OS concentrations. The correlations and quantitative findings from this study will assist product developers in selecting health-promoting sugar replacer ingredients that impart desirable texture and shelf-life properties in starch-containing foods.

Mechanisms of the different effects of sucrose, glucose, fructose, and a glucose-fructose mixture on wheat starch gelatinization, pasting, and retrogradation.

The gelatinization, pasting, and retrogradation of starch influence texture, quality, and shelf-life attributes of many foods. The purpose of this work was to document the effects of a 50:50 glucose:fructose (glc:fru) mixture and sucrose solutions on these starch traits to provide a fundamental basis to explain the different texture and shelf-life attributes of baked goods formulated with these sugars. Differential scanning calorimetry, rapid visco analyzer, and oscillatory rheometry were used to quantify the effects of glucose, fructose, glc:fru mixture, and sucrose at different concentrations (0% to 60% w/w), on the gelatinization temperature, pasting, and retrogradation properties of wheat starch. Distinct differences were found between the effects of sucrose and those of the monosaccharides including the glc:fru mixture. Sucrose elevated Tgel and pasting temperature most and decreased other RVA parameters compared to the monosaccharides as concentration increased. Fructose and the glc:fru mixture promoted amylopectin retrogradation, while retrogradation was inhibited in sucrose and glucose solutions. The glc:fru mixture had similar effects on starch properties compared to fructose under static measurement conditions (DSC), and the effects were in between those of glucose and fructose under dynamic conditions when shear was applied (RVA and rheology). These effects are explained by the phase separation and/or solute partitioning of the monosaccharide constituents of the glc:fru mixture. Sugar solution physicochemical properties correlated strongly with starch gelatinization and retrogradation. The results substantiate the important relationship between sugar physicochemical properties and solution dynamics with starch thermal properties, which in turn affect the texture and structure of starch-containing food products. PRACTICAL APPLICATION: The quality attributes of starch-containing baked goods are influenced by how different amounts and types of sugars affect starch cooking properties. The underlying mechanisms of the different sugar effects involve solution viscosity, intermolecular hydrogen bonding, and phase separation. Substituting one sugar for another has less effect on these starch properties in products with lower sugar concentrations than in products with more sugar. Mixtures of sugars behave differently than single sugars in different conditions due to phase separation. Baked goods made with glucose:fructose mixtures in place of sucrose likely have higher amounts of gelatinized starch and increased firmness (i.e., staling or retrogradation) over time.

Variable Effects of Twenty Sugars and Sugar Alcohols on the Retrogradation of Wheat Starch Gels.

Starch retrogradation is desirable for some food textures and nutritional traits but detrimental to sensory and storage qualities of other foods. The objective of this study was to determine the impact of sweetener structure and concentration on the retrogradation of wheat starch gels. The effects of 20 sweeteners selected based on common food usage and stereochemical structures of interest, and ranging in concentration from 10 to 50%w/w, on the retrogradation of wheat starch gels were monitored spectrophotometrically over time. The sweeteners were sucrose, xylose, ribose, glucose, galactose, fructose, mannose, mannitol, L-sorbose, xylitol, tagatose, allulose, maltose, lactose, isomaltulose, isomalt, sorbitol, maltitol, and raffinose. Retrogradation rates and amounts were compared by Avrami equation rate constants (k = 0.1-0.7) and absorbance values measured on day 28 (Abs = 0.1-1.0), respectively. Both sweetener concentration and type significantly affected retrogradation. Gels made with sugar alcohols and high sweetener concentrations (≈≥40%) tended to retrograde more and faster, whereas gels made with sugars and low sweetener concentrations tended to have lower retrogradation rates and amounts. Sweeteners with more equatorial and exocyclic hydroxyl groups (e.g., glucose and maltitol) and those with larger molar volumes (e.g., isomaltulose and raffinose) tended to increase the rate and amount of retrogradation, particularly at higher concentrations. The impact of sweeteners on retrogradation was a balance of factors that promoted retrogradation (intermolecular interactions and residual short-range molecular order) and inhibiting behaviors (interference at crystallization sites), which are influenced by sweetener concentration and structure. Understanding which sweeteners at which concentrations can be used to promote or inhibit retrogradation is useful for product formulation strategies.

Oligosaccharides elevate the gelatinization temperature of wheat starch more than sucrose, paving the way for their use in reduced sugar starch-based formulations.

The gelatinization of wheat starch influences the final structure and texture of baked goods. Sucrose effectively elevates the gelatinization temperature (Tgel) of starch more than many sweeteners, and maintaining a higher Tgel has been a challenge while reducing the amount of sucrose in baked goods. The objective of this study was to quantify the effects of 14 different oligosaccharides (OS: maltose, isomaltulose, kestose, maltotriose, melezitose, raffinose, stachyose, a fructo-OS, a galacto-OS, an isomalto-OS, lactosucrose, a xylo-OS, and two glucose-based dextrins), allulose, and sucrose at different concentrations (0 to 60% w/w) on the Tgel of wheat starch using DSC, and to determine which OS physicochemical properties best explained the Tgel results. OS type and concentration significantly altered Tgel. Many OS elevated the Tgel as much as or more than sucrose at the same solution concentrations, while allulose did not. The onset Tgel in water was 60 °C, in 60% sucrose was 96 °C, in 60% allulose was 80 °C, and Tgel increased up to 107-108 °C in 60% fructo-OS and Nutriose® solutions. The effects of OS on Tgel correlated most strongly (r > 0.95) with two OS solution parameters: the solvent effective volume fraction (ϕw,eff, related to solute intermolecular hydrogen bond density) and solution viscosity, to a lesser extent with solution water activity, and not to the glass transition temperature of the OS. Based on Tgel elevation, many of the OS are promising sucrose replacements in baked goods, which could facilitate their use in desirable higher fiber, reduced sugar starch-based baked product formulations.

Effect of pH and concentration on the chemical stability and reaction kinetics of thiamine mononitrate and thiamine chloride hydrochloride in solution.

Thiamine (vitamin B1) is an essential micronutrient in the human diet, found both naturally and as a fortification ingredient in many foods and supplements. However, it is susceptible to degradation due to heat, light, alkaline pH, and sulfites, among effects from other food matrix components, and its degradation has both nutritional and sensory implications as in foods. Thiamine storage stability in solution was monitored over time to determine the effect of solution pH and thiamine concentration on reaction kinetics of degradation without the use of buffers, which are known to affect thiamine stability independent of pH. The study directly compared thiamine stability in solutions prepared with different pHs (3 or 6), concentrations (1 or 20 mg/mL), and counterion in solution (NO3-, Cl-, or both), including both commercially available salt forms of thiamine (thiamine mononitrate and thiamine chloride hydrochloride). Solutions were stored at 25, 40, 60, and 80 °C for up to one year, and degradation was quantified by high-performance liquid chromatography (HPLC) over time, which was then used to calculate degradation kinetics. Thiamine was significantly more stable in pH 3 than in pH 6 solutions. In pH 6 solutions, stability was dependent on initial thiamine concentration, with the 20 mg/mL thiamine salt solutions having an increased reaction rate constant (kobs) compared to the 1 mg/mL solutions. In pH 3 solutions, kobs was not dependent on initial concentration, attributed to differences in degradation pathway dependent on pH. Activation energies of degradation (Ea) were higher in pH 3 solutions (21-27 kcal/mol) than in pH 6 solutions (18-21 kcal/mol), indicating a difference in stability and degradation pathway due to pH. The fundamental reaction kinetics of thiamine reported in this study provide a basis for understanding thiamine stability and therefore improving thiamine delivery in many foods containing both natural and fortified thiamine.

Antioxidant Films from Cassava Starch/Gelatin Biocomposite Fortified with Quercetin and TBHQ and Their Applications in Food Models.

Edible and active packaging are attractive for use in food packaging applications due to their functionality and sustainability. This research developed new antioxidant active food packaging materials from cassava starch/gelatin (7:3 w/w) composite films with varied antioxidant types (quercetin and tertiary butylhydroquinone (TBHQ)) and concentrations (0-200 mg/200 mL film-forming solution) and evaluated their properties. Antioxidant addition altered the mechanical and barrier properties of the films. At 34% relative humidity (RH), increasing the concentration of quercetin increased the tensile strength and decreased the elongation at break of the composite films. Increasing quercetin and TBHQ contents increased the film water solubility and water vapor transmission rate. Intermolecular interactions between the antioxidants and films, as found in Fourier transform infrared (FT-IR) spectra and XRD micrographs, were related to the changed film functionalities. In food application studies, the cassava starch/gelatin films containing quercetin and TBHQ retarded the oxidation of lard (more than 35 days) and delayed the redness discoloration of pork. Cassava starch/gelatin composite films integrated with quercetin and TBHQ can be utilized as active packaging that delays oxidation in foods.

Chemical stability and reaction kinetics of thiamine mononitrate in the aqueous phase of bread dough.

Thiamine is a water-soluble essential micronutrient, and grains are the main source of thiamine in the human diet. Refining processes reduce thiamine content; therefore, many flours are enriched with thiamine. Further processes, such as heating (baking), destabilize thiamine. In doughs, thiamine partitions into the aqueous phase (dough liquor). The objective of this study was to document temperature effects on thiamine degradation reaction kinetics in dough liquor. Two concentrations of thiamine mononitrate (1 and 20 mg/mL) were added to dough liquor (the supernatant of centrifuged bread dough) and control solutions (water and pH 6-adjusted water). Samples were stored at controlled temperatures (25, 40, 60, 70, and 80 °C) for up to 6 months, and thiamine degradation was quantified over time using high-performance liquid chromatography. Thiamine degradation kinetics, including the observed reaction rate constant (kobs) and activation energy (Ea) of degradation, were calculated. Dough liquor ingredients stabilized thiamine in most cases when compared to the pH 6 control solutions, especially in the samples containing more thiamine. Thiamine degradation in dough liquor generally followed similar trends to those in the controls: thiamine degraded more quickly in the 20 mg/mL solutions than in 1 mg/mL solutions (with one exception), and increasing temperature led to increased thiamine degradation. However, kobs ranged from 0.0019-0.22 days-1 in dough liquor and 0.0003-0.46 in control solutions, with differences attributed to interactions with components in the dough liquor. The Ea of thiamine degradation was ~90 kJ/mol in the control samples regardless of vitamin concentration but differed between vitamin concentrations in the dough liquor (95 and 60 kJ/mol in 1 and 20 mg/mL solutions, respectively), indicating that a different degradation pathway may have occurred in dough liquor. The different thiamine stability trends in dough liquor compared to control solutions indicate that food formulation has a substantial impact on the chemical behaviors of thiamine.

The effects of commercially available sweeteners (sucrose and sucrose replacers) on wheat starch gelatinization and pasting, and cookie baking.

A variety of sucrose replacers (SRs) are increasing in popularity for reducing sucrose usage in low moisture baked goods (cookies, biscuits, etc.). The goal of this study was to link SR physicochemical properties to their observed effects on starch thermal properties, including results from differential scanning calorimetry, rapid viscoanalysis, particle size analysis, and model wire-cut cookie baking performance. The 12 SRs examined in this study were: Truvia, Splenda, Swerve, coconut palm sugar, Monk Fruit, erythritol, Benefiber, Miralax, blue agave syrup, yacon syrup, Sukrín Fiber Gold Syrup, and date syrup. The onset gelatinization temperature (Tgel ) of wheat starch increased significantly (P < 0.05) as sucrose and SR concentration increased (0 to 60% w/w), with significant variations in Tgel found between different sweetener types at the same concentration. Generally, as solution concentration increased, the larger SRs (degree of polymerization [DP]> 10) decreased paste viscosity (peak and final), decreased granule swelling, and increased Tgel compared to the control (water). The smaller SRs (DP < 10) increased both paste viscosity (peak and final) and granule swelling, unlike the larger SRs, and did not increase Tgel as much as larger SRs. The SRs which performed similar to sucrose in model cookie baking (fracturability, spread, color, etc.) and effects on starch properties (Tgel , paste viscosity, and granule swelling) were yacon, Sukrín, date syrups, and coconut palm sugar. The results linking sweetener physicochemical properties to their effects on starch gelatinization, pasting, and swelling can be used to guide reformulation strategies for potentially reducing sugar and/or increasing fiber content in foods. PRACTICAL APPLICATION: Several commercially available natural sweeteners and polymers (coconut palm sugar, date syrup, yacon syrup, Sukrín Fiber Gold syrup, and Benefiber) show promise for reducing or replacing sucrose in cookies, and other low-moisture baked goods, based on their similar effects on wheat starch gelatinization, pasting, and swelling, as well as performance in cookie baking trials. Compared to sucrose, some of these ingredients have a lower glycemic response and higher dietary fiber content, and act as prebiotics, thereby providing potential health benefit.

Effects of polyphenols on crystallization of amorphous sucrose lyophiles.

The crystallization of amorphous sucrose in food products can greatly affect the quality of foods. This study investigated the effects of polyphenols on the crystallization of amorphous sucrose lyophiles. Monoglycosylated, polyglycosylated, and aglycones with differing polyphenol backbones were studied, in addition to bulk food ingredients containing a high concentration of polyphenols. Solutions containing sucrose with and without polyphenols (1 and 5%) were lyophilized, stored in RH-controlled desiccators, and analyzed by x-ray diffraction. Moisture sorption studies, Karl Fischer titration, and differential scanning calorimetry were also completed. Polyphenol addition delayed sucrose crystallization by up to 6.4x compared to the control. Structure played the most significant role in efficacy of polyphenols in delaying sucrose crystallization, more than Tg or hygroscopicity. Glycosylated polyphenols were more effective than aglycones, polyphenols with (2,1) glycosidic linkages were more effective than those with (6,1) linkages, and bulk food ingredients were the most effective at delaying sucrose crystallization.

Amorphization of Thiamine Mononitrate: A Study of Crystallization Inhibition and Chemical Stability of Thiamine in Thiamine Mononitrate Amorphous Solid Dispersions.

This study investigated thiamine degradation in thiamine mononitrate (TMN):polymer solid dispersions, accounting for the physical state of the vitamin and the recrystallization tendency of TMN in these dispersions. Results were compared with those from solid dispersions containing a different salt form of thiamine (thiamine chloride hydrochloride (TClHCl)). TMN:polymer dispersions were prepared by lyophilizing solutions containing TMN and amorphous polymers (pectin and PVP (polyvinylpyrrolidone)). Samples were stored in controlled temperature and relative humidity (RH) environments for eight weeks and monitored periodically by X-ray diffraction and high performance liquid chromatography (HPLC). Moisture sorption, glass transition temperature (Tg), intermolecular interactions, and pH were also determined. Similar to the TClHCl:polymer dispersions, thiamine was more chemically labile in the amorphous state than the crystalline state, when present in lower proportions in amorphous TMN:polymer dispersions despite increasing Tg values, when environmental storage conditions exceeded the Tg of the dispersion, and when co-formulated with PVP compared to pectin. When thiamine remained as an amorphous solid, chemical stability of thiamine did not differ as a function of counterion present (TMN vs. TClHCl). However, storage at 75% RH led to hydration of thiamine:PVP dispersions, and the resulting pH of the solutions as a function of thiamine salt form led to a higher chemical stability in the acidic TClHCl samples than in the neutral TMN samples.

Moisture sorption behaviors, water activity-temperature relationships, and physical stability traits of spices, herbs, and seasoning blends containing crystalline and amorphous ingredients.

Spices, herbs, and seasoning blends containing both crystalline and amorphous ingredients are common throughout the food industry but may exhibit unwanted clumping or caking during storage. Crystalline and amorphous ingredients are known to respond differently to increases in relative humidity (RH) and temperature. The aim of this study was to better characterize what happens to moisture sorption behaviors, water-solid interactions, and physical stability when crystalline and amorphous ingredients are co-formulated in seasoning blends. Spices, herbs, and seasoning blends, 25 in total, were studied individually and in blends of increasing complexity (binary, ternary, and quaternary) with sucrose, salt, and maltodextrin. The effects of increasing temperature and RH on moisture content, moisture sorption profiles, water activity (aw), glass transition temperature (Tg), including Gordon-Taylor modeling, physical appearance, and degree of clumping were measured. Crossover points, the temperature at which the aw of the amorphous ingredient(s) and the deliquescence RH of the crystalline ingredient(s) in a blend intersect, were also calculated. Caking was observed when storage conditions (RH and/or temperature) exceeded the Tg of a blend or the deliquescence RH of a crystalline ingredient in the blend. When amorphous and crystalline ingredients were blended, synergistic moisture sorption and increased caking was observed. When multiple crystalline ingredients were present, mutual deliquescence further increased the sensitivity of the blend to moisture. When environmental conditions exceeded the crossover temperature, degree of caking increased, and physical appearance was altered due to the induced deliquescence of the crystalline ingredient(s) by the aw of the amorphous ingredient(s). In general, as complexity of blends increased, sensitivity to moisture also increased, and physical stability of the blends decreased. The results of this study provide valuable information for increasing the physical stability of complex seasoning blends based on moisture sorption behaviors.

Amorphization of Thiamine Chloride Hydrochloride: Effects of Physical State and Polymer Type on the Chemical Stability of Thiamine in Solid Dispersions.

Thiamine is an essential micronutrient, but delivery of the vitamin in supplements or foods is challenging because it is unstable under heat, alkaline pH, and processing/storage conditions. Although distributed as a crystalline ingredient, thiamine chloride hydrochloride (TClHCl) likely exists in the amorphous state, specifically in supplements. Amorphous solids are generally less chemically stable than their crystalline counterparts, which is an unexplored area related to thiamine delivery. The objective of this study was to document thiamine degradation in the amorphous state. TClHCl:polymer dispersions were prepared by lyophilizing solutions containing TClHCl and amorphous polymers (pectin and PVP (poly[vinylpyrrolidone])). Samples were stored in controlled temperature (30-60 °C) and relative humidity (11%) environments for 8 weeks and monitored periodically by X-ray diffraction (to document physical state) and HPLC (to quantify degradation). Moisture sorption, glass transition temperature (Tg), intermolecular interactions, and pH were also determined. Thiamine was more labile in the amorphous state than the crystalline state and when present in lower proportions in amorphous polymer dispersions, despite increasing Tg values. Thiamine was more stable in pectin dispersions than PVP dispersions, attributed to differences in presence and extent of intermolecular interactions between TClHCl and pectin. The results of this study can be used to control thiamine degradation in food products and supplements to improve thiamine delivery and decrease rate of deficiency.

Effects of Sugars and Sugar Alcohols on the Gelatinization Temperatures of Wheat, Potato, and Corn Starches.

The gelatinization temperature (Tgel) of starch increases in the presence of sweeteners due to sweetener-starch intermolecular interactions in the amorphous regions of starch. Different starch botanical sources contain different starch architectures, which may alter sweetener-starch interactions and the effects of sweeteners on Tgels. To document these effects, the Tgels of wheat, potato, waxy corn, dent corn, and 50% and 70% high amylose corn starches were determined in the presence of eleven different sweeteners and varying sweetener concentrations. Tgels of 2:1 sweetener solution:starch slurries were measured using differential scanning calorimetry. The extent of Tgel elevation was affected by both starch and sweetener type. Tgels of wheat and dent corn starches increased the most, while Tgels of high amylose corn starches were the least affected. Fructose increased Tgels the least, and isomalt and isomaltulose increased Tgels the most. Overall, starch Tgels increased more with increasing sweetener concentration, molar volume, molecular weight, and number of equatorial and exocyclic hydroxyl groups. Starches containing more short amylopectin chains, fewer amylopectin chains that span through multiple clusters, higher number of building blocks per cluster, and shorter inter-block chain lengths exhibited the largest Tgel increases in sweetener solutions, attributed to less stable crystalline regions.

Relative humidity-temperature transition boundaries for anhydrous ß-caffeine and caffeine hydrate crystalline forms.

Caffeine is a hydrate-forming polymorphic crystalline compound that can exist in α, ß, and hydrate forms. Phase transitions between hydrate and anhydrous forms of a crystalline ingredient, and related water migration, can create product quality challenges. The objective of this study was to determine the relative humidity (RH)-temperature phase boundary between anhydrous ß-caffeine and caffeine hydrate. The ß-caffeine→caffeine hydrate and caffeine hydrate→ß-caffeine RH-temperature transition boundaries were determined from 20 to 45 °C using a combination of water activity (aw ) controlled solution and vapor-mediated equilibration, moisture sorption, powder X-ray diffraction, and Fourier-transform infrared spectroscopy techniques. Two transition boundaries were measured: the ß-caffeine→caffeine hydrate transition boundary (0.835 ± 0.027 aw at 25 °C) was higher than the caffeine hydrate→ß-caffeine transition boundary (0.625 ± 0.003 aw at 25 °C). Moisture sorption rates for ß-caffeine, even at high RHs (>84% RH), were slow. However, caffeine hydrate rapidly dehydrated at low RHs (<30% RH) into a metastable transitional anhydrous state with a similar X-ray diffraction pattern to metastable α-caffeine. Exposing this dehydrated hydrate to higher RHs (>65% RH) at lower temperatures (20 to 30 °C) resulted in full restoration to a 4/5 caffeine hydrate. This transitional anhydrous state was unstable and converted to a less hygroscopic state after annealing at 50 °C and 0% RH for 1 day. It was postulated that the caffeine hydrate→ß-caffeine was the true ß-caffeine↔caffeine hydrate phase boundary and that ß-caffeine could be metastable above the caffeine hydrate→ß-caffeine transition boundary. These caffeine RH-temperature transition boundaries could be used for selecting formulation and storage conditions to maintain the desired caffeine crystalline form. PRACTICAL APPLICATION: Caffeine can exist as either an anhydrous (without water) or hydrate (internalized water) crystalline state. The stability of each caffeine crystalline form is dictated by humidity (or water activity) and temperature, and these environmental stability boundaries for the caffeine crystalline forms are reported in this manuscript. Conversions between the two crystalline states can lead to deleterious effects; for example, the presence of caffeine hydrate crystals in a low water activity food (e.g., powder) could lead to the relocation of the water in caffeine to other ingredients in the food system, leading to unwanted water-solid interactions that could cause clumping and/or degradation.

Physical and Antioxidant Properties of Cassava Starch-Carboxymethyl Cellulose Incorporated with Quercetin and TBHQ as Active Food Packaging.

Antioxidant integration has been advocated for in polymer films, to exert their antioxidative effects in active packaging. In this study, the new antioxidant food packaging made from cassava starch-carboxymethyl cellulose (CMC), which is biodegradable, edible and inexpensive, was developed. Their properties were determined and applied in food models for application. Antioxidants (quercetin and tertiary butylhydroquinone (TBHQ)) were added at various concentrations into cassava starch-carboxymethyl cellulose (CMC) (7:3 w/w) films containing glycerol (30 g/100 g starch-CMC) as a plasticizer. The effects of quercetin and TBHQ concentrations on the mechanical properties, solubility, antioxidative activity, and applications of the films were investigated. Addition of antioxidant improved tensile strength, but reduced elongation at break of the cassava starch-CMC film. Cassava starch-CMC films containing quercetin showed higher tensile strength, but lower elongation at break, compared to films with TBHQ. Increases in quercetin and TBHQ content decreased water solubility in the films. Both the total phenolic content and antioxidative activity (DPPH scavenging assay) still remained in films during storage time (30 days). In application, cassava starch-CMC film containing quercetin and TBHQ can retard the oxidation of lard (35-70 days) and delay the discoloration of pork.

RH-temperature stability diagram of α- and ß-anhydrous and monohydrate lactose crystalline forms.

Lactose crystals exhibit polymorphic, deliquescent, and hydrate-forming traits and can exist in monohydrate, ß-anhydrate, stable α-anhydrate, and hygroscopic α-anhydrate (isomorphic desolvate) forms. The objective of this study was to identify the relative humidity (RH) and temperature boundaries at which anhydrate-hydrate transitions and deliquescence occur for these lactose crystal forms. The deliquescence point (RH0) of lactose monohydrate was determined by measuring the water activity (aw) of a saturated solution, and the RH0s of the anhydrates were determined using dynamic vapor sorption measurement techniques. Increasing temperatures from 20 to 50 °C resulted in decreases in RH0 from 99 to 98% RH for the monohydrate, 89 to 82% RH for the ß-anhydrate, and 87 to 82% RH for the stable α-anhydrate. The effects of temperature on the anhydrate-hydrate RH boundaries were determined using a combination of controlled aw equilibration, powder X-ray diffraction, and Fourier-transform infrared spectroscopy techniques. Increasing temperature from 20 to 50 °C resulted in increasing RHs of the anhydrate-to-hydrate boundaries: the ß-anhydrate-to-monohydrate boundary increased from 77 to 79% RH, the stable α-anhydrate-to-monohydrate from 63 to 79% RH, and the unstable α-anhydrate-to-monohydrate from 10 to 13% RH. This is the first report of an RH-temperature stability map for lactose crystalline forms.

Effects of emulsifiers on the moisture sorption and crystallization of amorphous sucrose lyophiles.

The crystallization of amorphous sucrose can be problematic in food products. This study explored how emulsifiers (a range of sucrose esters, polysorbates, and soy lecithin) impact the moisture sorption and crystallization of amorphous sucrose lyophiles. Solutions containing sucrose with and without emulsifiers were lyophilized, stored in desiccators, and analyzed by X-ray diffraction, infrared spectroscopy, and polarized light microscopy over time. Moisture sorption techniques, Karl Fischer titration, and differential scanning calorimetry were also used. Different emulsifiers had varying impacts on sucrose crystallization tendencies. Polysorbates enhanced sucrose crystallization, decreasing both the RH and time at which sucrose crystallized. These lyophiles did not collapse upon crystallization, unlike all other samples, indicating the likelihood of variations in nucleation sites and crystal growth. All other emulsifiers stabilized amorphous sucrose by up to a factor of 7x, even in the presence of increased water absorbed and independent of glass transition temperatures, indicating emulsifier structure governed sucrose crystallization tendencies.

RH-Temperature Stability Diagram of the Dihydrate, ß-Anhydrate, and α-Anhydrate Forms of Crystalline Trehalose.

Trehalose crystals exhibit polymorphic, deliquescent, and hydrate-forming traits and can exist in dihydrate, ß-anhydrate, or α-anhydrate (isomorphic desolvate) forms. The objective of this study was to identify the relative humidity (RH) and temperature boundaries for phase changes of these different trehalose crystal forms. The deliquescence points (RH0 s) of the anhydrate and dihydrate trehalose crystals were determined from 20 to 50 °C using a combination of water activity and dynamic vapor sorption measurement techniques. Increasing temperatures from 20 to 50 °C resulted in decreases in RH0 from 95.5% to 90.9% RH for the dihydrate and 69.9% to 62.0% RH for the ß-anhydrate. The effects of temperature on the anhydrate-hydrate RH boundaries were also determined, using a combination of equilibration in controlled water activity solutions, powder X-ray diffraction, and Fourier-transform infrared spectroscopy techniques. Increasing temperatures resulted in increases in the anhydrate-hydrate RH boundaries. The irreversible ß-anhydrate to dihydrate boundary increased from 44.9% to 57.8% RH, and the reversible α-anhydrate to dihydrate boundary increased from 10% to 25% RH, as temperature increased from 20 to 50 °C. This is the first report of an RH-temperautre stability map for crystalline trehalose. PRACTICAL APPLICATION: The manuscript addresses the issue of the physical stability and phase transformations of crystalline trehalose stored in different temperature and relative humidity environments. Unwanted hydrate formation or dehydration of crystal hydrates can lead to other undesirable water-solid interactions and/or physical modifications that have the potential to influence product quality and delivery traits. Therefore, this study identified relative humidity and temperature stability boundaries of the different trehalose crystal forms, using a variety of established and novel techniques to create a relative humidity-temperature stability map of crystalline trehalose from 20 to 50 °C.

Effects of Controlled Relative Humidity Storage on Moisture Sorption and Amylopectin Retrogradation in Gelatinized Starch Lyophiles.

Water plays a significant role in the gelatinization and retrogradation (crystallization) of starch. Amylopectin crystalline regions can adopt several hydrated polymorphic forms; however, reports differ on the migration of water during retrogradation. The objectives of this study were to determine the moisture sorption patterns of gelatinized starch lyophiles during retrogradation in controlled relative humidity (RH) environments and document the amylopectin polymorph(s) formed. Starches from different botanical sources containing A-type and B-type amylopectin polymorphs were studied. Suspensions of starch were heated and then frozen and freeze-dried to make primarily amorphous matrices. Moisture sorption profiles of the dried samples were collected from 5% RH to 95% RH at 25 °C. To capture the retrogradation event, sample masses were also monitored at constant RHs over time (95%, 92.5%, and 90% RH). Powder X-ray diffraction was used to document the physical state of the samples, including the amylopectin polymorph formed upon retrogradation, and differential scanning calorimetry was used to determine glass transition temperatures (Tg s). In all lyophiles, water was first absorbed (mass gain), and if a critical water content was reached (at ≥92.5%RH), sample Tg s dropped below room temperature and concurrent retrogradation and water expulsion (mass loss) occurred, regardless of starch botanical source and whether A- or B-type polymorphs were formed. Overall, retrogradation and water expulsion increased as storage RH increased. These results offer further knowledge into the role of water in amylopectin retrogradation and the relationship among starch type, environmental RH, moisture sorption prior to retrogradation, and water redistribution during retrogradation. PRACTICAL APPLICATION: Starch gelatinization and retrogradation require molecular mobility, which is facilitated by water. Limited retrogradation occurred in lyophiles in the glassy state (90% RH, 25 °C), but increasing the storage RH (to ≥92.5% RH) resulted in increasing amylopectin retrogradation (note: many baked products have water activities in this range). Regardless of starch type (botanical source and amylose content), when the storage RH was high enough, the starch lyophiles first absorbed water, which depressed the Tg below the storage temperature, and then exhibited concomitant retrogradation and water expulsion. The water expelled during amylopectin retrogradation was not (fully) retained in the amorphous starch fraction, which is why samples lost weight. Water leaving the starch matrix during retrogradation could pose challenges for quality, texture, and shelf-life of starch-based products.

Optimizing the Quality of Food Powder Products: The Challenges of Moisture-Mediated Phase Transformations.

Water is ubiquitous in the environment and is present to varying degrees even within dry powder products and most ingredients. Water migration between the environment and a solid, or between different components of a product, may lead to detrimental physical and chemical changes. In efforts to optimize the quality of dry products, as well as the efficiency of production practices, it is crucial to understand the cause-effect relationships of water interactions with different solids. Therefore, this review addresses the basis of moisture migration in dry products, and the modes of water vapor interactions with crystalline and amorphous solids (e.g., adsorption, capillary condensation, deliquescence, crystal hydrate formation, absorption into amorphous solids) and related moisture-induced phase and state changes, and provides examples of how these moisture-induced changes affect the quality of the dry products.