Influence of simultaneous variations in temperature and relative humidity on chemical stability of two vitamin C forms and implications for shelf life models

A Stable and Local H2 Nanogenerator for Antifading Responses

Persistent inflammation effects existed in the senescence microenvironment, and hydrogen (H2) was an antioxidant stress agent and could solve the aging and inflammation. In view of the issue of low solubility of H2 and conversion efficiency of traditional hydrogen therapy, an in-site hydrogen production system (HPS) was designed by using liposome as a compartment, emodin as a photosensitizer, l-ascorbic acid-2-phosphate trisodium salt (AAP) as hydrogen sources, and Au NPs as photocatalysts. Different from the commonly used chlorophyll A, emodin with strong absorption in the wide range of 200-500 nm could absorb more photons to form electrons for the participation of H2 generation. Emodin- and AAP-embedded HPS largely increased stability at 50 °C for 28 days. HPS facilitated the decrease of inflammatory factors of TNF-α, IL-6, and ROS in RAW264.7 cells, as well as the elimination of senescence-associated β-galactosidase, realizing convenient and efficient antifading responses. But strikingly, the constructed HPS can penetrate the pig skin in transdermal experiments and showed huge prospects for the application of antifading cosmetics.

Calculating pH-solubility profile and pHmax for monoprotic salts of poorly water-soluble weak bases

Pharmaceutical salts are a commonly used strategy to improve the bioavailability of poorly water-soluble active pharmaceutical ingredients (APIs). The selected salt form is expected to have high solubility to obtain optimal supersaturation and sufficient physical stability for adequate shelf life. In this paper, we aim to develop equations to describe critical parameters of salts, including pH-solubility profile and pHmax. The equations serve as a valuable tool to aid in the calculation of salt solubility at pH below the pHmax in the presence of common counter ions. This provides the knowledge to assess the risks of pre-selection of the salt formers without the necessity of salt synthesis. The solubilities calculated by this model demonstrate good agreement with experimental solubility results reported in the literature. Compared to the conventional approaches for salt solubility and pHmax calculation, our model stands out, especially for poorly water-soluble bases with low pKa values, which benefit the most from salt formation. Moreover, the equations are used to support the concept that salt selection should focus on finding salt forms with sufficient solubility, rather than the most soluble salt, as excessively high solubility could be detrimental to physical stability.

Accelerated Shelf Life Modeling of Appearance Change in Drug Products Using ASAPprime®

An accelerated stability model approach was demonstrated to accurately predict the long-term shelf life of example drug substances and drug products (indigo carmine tablets and L-ascorbic acid powder) where appearance changes were shelf life-limiting. The products were exposed outside of packaging to conditions from 50-90 °C and 0-80% relative humidity for up to one month to accelerate appearance changes. The appearance changes of stressed samples were quantitated using the CIELAB color scale (calculated ΔE*), where a visual assessment of appearance changes likely to be noticeable was used to assign a ΔE* specification limit. ASAPprime^® software was employed to create an isoconversion paradigm, modeled in packaging by the moisture-modified Arrhenius equation, that predicted the color changes of the products within the error bars of the model to nine months at 25 °C/60% RH, 30 °C/65% RH, and 40 °C/75% RH. Overall, these case studies indicate that the ASAPprime^® approach for accelerated stability studies are a fast, accurate approach to modeling appearance changes.

Food-inspired innovations to improve the stability of active pharmaceutical ingredients

Food-processing and pharmaceutical industries share a lot of stability issues against the same physical, chemical, and microbiological phenomena. They also share some solutions to improve the stability as the use of preservatives and packaging. Ecological concerns lead to the development of tremendous innovations in food. Some of these innovations could also be beneficial in the pharmaceutical domain. The objective of this review is to evaluate the potential application of these findings in the pharmaceutical field and the main limits in terms of toxicity, environmental, economic and regulatory issues. The principal factors influencing the shelf-life were highlighted through the description of the stability studies usually performed in the pharmaceutical industry (according to European guidelines). To counter those factors, different solutions are currently available as preservatives and specific packaging. They were described and debated with an overview of recent food innovations in each field. The limits of the current solutions in the pharmaceutical field and the innovation in the food field have inspired a critical pharmaceutical outlook. The active and intelligent packaging for active pharmaceutical ingredients of the future is imagined.

Developing ultrasound-assisted hot-air and infrared drying technology for sweet potatoes

The influence of ultrasound (US) pretreatments combined with infrared (IRD) and hot-air (HAD) drying on drying kinetics, mathematical modeling, bioactive compounds (antioxidant activities, Vitamin C, phenolics, and flavonoid contents), qualitative properties (β-carotene, total carotenoids, color indexes, textural profile), enzyme inactivation, and exergetic analysis of sweet potatoes. The US pretreatment at 40 kHz combined with IRD and HAD (70 °C) significantly lessened the drying time and water contents. Besides, it did not affect the sweet potato's bioactive components and other quality-related attributes. The samples' activation energy (E_a) ranged from 17.60 to 29.86 kJ/mol for both dryers, with R² (0.999-0.9809). Control samples had the highest specific energy consumption (SEC) due to the extended drying period, whereas ultrasound (40 kHz) treated samples had the lowest SEC during HAD and IRD at 80 °C. The thermodynamic parameters indicated that increasing the drying temperature lowers the enthalpy and Gibbs free energy, while entropy resulted in negative values. HAD had better textural qualities (hardness and resilience). The US pretreatments followed by HAD or IRD may lead to an energy-efficient method with acceptable quality maintenance.

Selective production of retinol by engineered Saccharomyces cerevisiae through the expression of retinol dehydrogenase

Retinol is a fat-soluble vitamin A that is widely used in the food and pharmaceutical industries. Currently, retinol is commercially produced by chemical synthesis. Microbial production of retinol has been alternatively explored but restricted to a mixture of retinoids including retinol, retinal, and retinoic acid. Thus, we introduced heterologous retinol dehydrogenase into retinoids mixture-producing Saccharomyces cerevisiae for the selective production of retinol using xylose. Expression of human RDH10 and Escherichia coli ybbO led to increase in retinol production, but retinal remained as a major product. In contrast, S. cerevisiae harboring human RDH12 produced retinol selectively with negligible production of retinal. The resulting strain (SR8A-RDH12) produced retinol only. However, more glycerol was accumulated due to intracellular redox imbalance. Therefore, Lactococcus lactis noxE coding for H₂ O-forming NADH oxidase was additionally introduced to resolve the redox imbalance. The resulting strain produced 52% less glycerol and more retinol with a 30% higher yield than a parental strain. As the produced retinol was not stable, we examined culture and storage conditions including temperature, light, and antioxidants for the optimal production of retinol. In conclusion, we achieved selective production of retinol efficiently from xylose by introducing human RDH12 and NADH oxidase into S. cerevisiae.

Stability of sodium ascorbyl phosphate in the water-glycerol system

Sodium ascorbyl phosphate is a hydrophilic derivative of ascorbic acid with better stability compared to the parent compound. However, sodium ascorbyl phosphate is not as stable in solution as it is in the solid state, and it has been found to degrade, with accompanying discoloration, under the influence of different conditions. Here, the degradation mechanism of sodium ascorbyl phosphate in the water-glycerol system was revealed and the thermal degradation kinetics was shown to follow second-order kinetics. A thermal degradation prediction model was established and successfully fitted to the experimental data. In addition, the stability of sodium ascorbyl phosphate in the water-glycerol system during storage was investigated under different conditions, including changes in concentration, temperature, pH, light and oxygen, and metal ions. Sodium ascorbyl phosphate content was quantitatively measured via HPLC, and the color and pH values of the sample were qualitatively measured using a spectrophotometer and a pH meter, respectively. It was found that temperature and pH are the most important factors affecting the stability of sodium ascorbyl phosphate.

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.

Quality and In-Use Stability Comparison of Brand and Generics of Extended-Release Phenytoin Sodium Capsules

The objective of the present study was to understand quality of brand and generic products of phenytoin sodium by in vitro methods. Three commercial products were selected for the study, 1 brand and 2 generics (product-A, product-B, and product-C). Products were repacked in pharmacy vials and stored for 12 weeks at 30°C/75% RH to simulate in-use conditions. The products were examined visually and microscopically for morphologic changes, spectroscopic and diffractometric methods for chemical changes, and dissolution, assay, and impurities for performance evaluation. Capsules content of the product-A turned yellowish to dark orange color from initial white powder, which indicated a possible chemical interaction between lactose and the drug in addition to disproportionation. This was supported by pH, microscopic, spectroscopic, and X-ray diffraction data. Product-A failed to meet United States Pharmacopoeia dissolution specification of 75% in 120 min after 2-weeks whereas product-B and product-C failed at 6-weeks of in-use stability conditions exposure. Furthermore, product-A also failed to meet United States pharmacopoeia assay and impurities specifications in 12 weeks in-use period. In summary, this study indicated salt disproportionation, chemical interactions, and phase transformations of drug and excipients in the commercial products of phenytoin sodium, which may affect the clinical performance of the product.

Degradation of L-Ascorbic Acid in the Amorphous Solid State

Ascorbic acid degradation in amorphous solid dispersions was compared to its degradation in the crystalline state. Physical blends and lyophiles of ascorbic acid and polymers (pectins and polyvinylpyrrolidone [PVP]) were prepared initially at 50:50 (w/w), with further studies using the polymer that best inhibited ascorbic acid crystallization in the lyophiles in 14 vitamin : PVP ratios. Samples were stored in controlled environments (25 to 60 °C, 0% to 23% RH) for 1 mo and analyzed periodically to track the physical appearance, change in moisture content, physical state (powder x-ray diffraction and polarized light microscopy), and vitamin loss (high performance liquid chromatography) over time. The glass transition temperatures of select samples were determined using differential scanning calorimetry, and moisture sorption profiles were generated. Ascorbic acid in the amorphous form, even in the glassy amorphous state, was more labile than in the crystalline form in some formulations at the highest storage temperature. Lyophiles stored at 25 and 40 °C and those in which ascorbic acid had crystallized at 60 °C (≥70% ascorbic acid : PVP) had no significant difference in vitamin loss (P > 0.05) relative to physical blend controls, and the length of storage had little effect. At 60 °C, amorphous ascorbic acid lyophiles (≤60% ascorbic acid : PVP) lost significantly more vitamin (P < 0.05) relative to physical blend controls after 1 wk, and vitamin loss significantly increased over time. In these lyophiles, vitamin degradation also significantly increased (P < 0.05) at lower proportions of ascorbic acid, a scenario likely encountered in foods wherein vitamins are naturally present or added at low concentrations and production practices may promote amorphization of the vitamin.

PRACTICAL APPLICATION

Vitamin C is one of the most unstable vitamins in foods. This study documents that amorphous ascorbic acid is less stable than crystalline ascorbic acid in some environments (for example, higher temperatures within 1 wk), especially when the vitamin is present at low concentrations in a product. These findings increase the understanding of how material science properties influence the stability of vitamin C.

Amorphization of thiamine chloride hydrochloride: A study of the crystallization inhibitor properties of different polymers in thiamine chloride hydrochloride amorphous solid dispersions

Amorphous solid dispersions of thiamine chloride hydrochloride (THCl) were created using a variety of polymers with different physicochemical properties in order to investigate how effective the various polymers were as THCl crystallization inhibitors. THCl:polymer dispersions were prepared by lyophilizing solutions of THCl and amorphous polymers (guar gum, pectin, κ-carrageenan, gelatin, and polyvinylpyrrolidone (PVP)). These dispersions were stored at select temperature (25 and 40°C) and relative humidity (0, 23, 32, 54, 75, and 85% RH) conditions and monitored at different time points using powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). Moisture sorption isotherms of all samples were also obtained. Initially amorphous THCl was produced in the presence of ≥40% w/w pectin, κ-carrageenan, gelatin, and guar gum or ≥60% w/w PVP. Trends in polymer THCl crystallization inhibition (pectin≥κ-carrageenan>gelatin>guar gum≫PVP) were primarily based on the ability of the polymer to interact with THCl via hydrogen bonding and/or ionic interactions. The onset of THCl crystallization from the amorphous dispersions was also related to storage conditions. THCl remained amorphous at low RH conditions (0 and 23% RH) in all 1:1 dispersions except THCl:PVP. THCl crystallized in some dispersions below the glass transition temperature (T_g) but remained amorphous in others at T~T_g. At high RHs (75 and 85% RH), THCl crystallized within one day in all samples. Given the ease of THCl amorphization in the presence of a variety of polymers, even at higher vitamin concentrations than would be found in foods, it is likely that THCl is amorphous in many low moisture foods.

Stability of vitamin C in fresh and freeze-dried capsicum stored at different temperatures

The objective of this study was to determine vitamin C stability in fresh and freeze-dried capsicum during storage at different temperatures. Fresh capsicum stored at 20 °C showed an initial decrease in vitamin C with a minimum peak after 2 days and then increased to a maximum peak after 13 days followed by a gradual decay. In general a gradual decrease of vitamin C was observed in the cases of fresh (i.e. stored at 5, -20, -40 °C) and freeze-dried capsicum stored at all temperatures (i.e. 60 to -40 °C). The degradation kinetics of vitamin C was modeled by zero and first order reaction and rate constants were estimated. The rate constant increased with the increase in storage temperature, while it was decreased with the decrease of moisture content. At storage temperature 5 °C, first order rate constants were observed as 7.1 × 10(-2), 7.7 × 10(-2), and 4.3 × 10(-3) day(-1) in the cases of samples containing moisture contents 94, 15 and 5 g/100 g sample, respectively.

Effect of temperature on the deliquescence properties of food ingredients and blends

Deliquescence is a first-order phase transformation of a crystalline solid to a saturated solution that is triggered at a defined relative humidity (RH), RH0. Previous studies demonstrated that the RH0 of an inorganic substance with a positive heat of solution (ΔH) will decrease with increases in temperature. In this study, the relationships between ΔH, solubility, and deliquescence RH for single-ingredient and multicomponent systems were investigated. The deliquescence RHs of inorganic and organic crystalline solids and their mixtures were measured at temperatures ranging from 20 to 40 °C using a water activity meter and various gravimetric moisture sorption analyzers. The deliquescence behavior as a function of temperature for organic food ingredients was thermodynamically modeled and followed similar trends to those of the previously investigated inorganic ingredients. Furthermore, the models can be used as a predictive approach to determine physical stability and deliquescence RHs of deliquescent ingredients and blends if the storage temperature and ingredient ΔH and solubility are known.

Color and chemical stability of a variety of anthocyanins and ascorbic acid in solution and powder forms

The color and chemical stabilities of six anthocyanins, including cyanidin 3-glucoside, highly purified and present in semipurified extracts (also containing other anthocyanins) from grape pomace, purple corn, and black rice, were determined in combination with ascorbic acid in solutions at differing pH values (3.0 and 4.0) and temperatures (6-40 °C) and lyophilized powders at different relative humidities (43-98% RH). Color and chemical changes were analyzed using CIELAB measurements and HPLC, respectively. In liquids, stability was inversely related to increasing pH and temperature; for powders, stability was inversely related to RH. The mutual destruction of anthocyanins and ascorbic acid in solution was confirmed, with unexpected new findings showing no significant stabilizing/destabilizing effect based upon anthocyanin structure, including differing flavylium core (three types) and type of acylation (two aliphatic, one cinnamic acid), or final extract purity.