Effect of different preservatives on the physicochemical characteristics and shelf stability of Rasmalai: A comparative study

Rasmalai is a very popular, delicious, and nutritious indigenous sweet dish in Indo-Pakistani civilization. It has a very short shelf life, i.e., up to 3 days. The study was designed to assess the effect of preservatives (potassium sorbate and calcium propionate) on the shelf stability of Rasmalai. Moreover, proximate composition and sensory evaluation of prepared Rasmalai were also carried out in the present study. In general, potassium sorbate and calcium propionate significantly increased the shelf life of Rasmalai. But treatment (R5) containing a combination of both potassium sorbate and calcium propionate (500 ppm each) improved its shelf life by up to 12 days by keeping good sensorial characteristics. The maximum total plate counts as well as yeast and molds were observed in control Rasmalai (without any preservatives) whereas minimum counts were found in R5 treatment containing a combination of both potassium sorbate and calcium propionate (500 ppm each). In conclusion, all the preservatives used in the present study were effective in enhancing the shelf life of Rasmalai but R5 treatment containing a combination of both potassium sorbate and calcium propionate (500 ppm each) was the most effective in enhancing shelf life without deleterious effect on sensorial characteristics.

Physicochemical characteristics, antioxidant potential, and shelf stability of developed roselle-fig fruit bar

Fruit bars are prepared by combining different ingredients which are wholesome and nutrient rich. The current study was designed to develop roselle-fig (different proportions) fruit bars and further investigate their physicochemical characteristics and antioxidant potential. Moreover, the prepared fruit bars were scrutinized for microbial and sensory characteristics to assess the appropriateness of ingredients during storage (up to 90 days). It was observed that there was gradual increase in moisture content with the passage of time, while ash, fat, fiber, and protein contents did not change significantly during storage. The pH and total soluble solid contents of these fruit bars during storage were 3.54-4.07 and 1.71-1.86 Brix, respectively. According to the mean values for sensory evaluation, T ₂ was preferred over other treatments. The bars received an acceptable sensory evaluation, demonstrating that they were suitable for 90 days of storage. Phytochemical quantities significantly increased in subsequent treatments, but decreased during storage in all the treatments. Similar trend was observed regarding total antioxidant and DPPH radical scavenging activities. The mineral contents increased significantly among the treatments. The microbial analysis of fruit bars exposed that the fruit were microbiologically safe. Hence, on the basis of the results obtained in this study, it may be concluded that the developed roselle-fig fruit bar would be acceptable and nutritious regarding physicochemical characteristics, microbiological quality, and antioxidant potential.

In Situ Absorption Characterization Guided Slot-Die-Coated High-Performance Large-Area Flexible Organic Solar Cells and Modules

Slot-die coating is recognized as the most compatible method for the roll-to-roll (R2R) processing of large-area flexible organic solar cells (OSCs). However, the photovoltaic performance of large-area flexible OSC lags significantly behind that of traditional spin-coating devices. In this work, two acceptors, Qx-1 and Qx-2, show quite different film-formation kinetics in the slot-die coating process. In situ absorption spectroscopy indicates that the excessive crystallinity of Qx-2 provides early phase separation and early aggregation, resulting in oversized crystal domains. Consequently, the PM6:Qx-1-based 1 cm² flexible device exhibits an excellent power conversion efficiency (PCE) of 13.70%, which is the best performance among the slot-die-coated flexible devices; in contrast, the PM6:Qx-2 blend shows a pretty poor efficiency, which is lower than 1%. Moreover, the 30 cm² modules based on PM6:Qx-1, containing six 5 cm² sub-cells, exhibit a PCE of 12.20%. After being stored in a glove box for over 6000 h, the PCE remains at 103% of its initial values, indicating excellent shelf stability. Therefore, these results show a promising future strategy for the upscaling fabrication of flexible large-area OSCs.

Enhancing long-term storage and stability of engineered living materials through desiccant storage and trehalose treatment

Engineered living materials (ELMs) have broad applications for enabling on-demand bioproduction of compounds ranging from small molecules to large proteins. However, most formulations and reports lack the capacity for storage beyond a few months. In this study, we develop an optimized procedure to maximize stress resilience of yeast-laden ELMs through the use of desiccant storage and 10% trehalose incubation before lyophilization. This approach led to over 1-year room temperature storage stability across a range of strain genotypes. In particular, we highlight the superiority of exogenously added trehalose over endogenous, engineered production in yielding robust preservation resilience that is independent of cell state. This simple, effective protocol enables sufficient accumulation of intracellular trehalose over a short period of contact time across a range of strain backgrounds without requiring the overexpression of a trehalose importer. A variety of microscopic analysis including µ-CT and confocal microscopy indicate that cells form spherical colonies within F127-BUM ELMs that have variable viability upon storage. The robustness of the overall procedure developed here highlights the potential for widespread deployment to enable on-demand, cold-chain independent bioproduction.

Structure and shelf stability of milk protein gels created by pressure-assisted enzymatic gelation

In this work, pressure-assisted enzymatic gelation was applied to milk proteins, with the goal of enhancing the structure and stability of pressure-created milk protein gels. High-pressure processing (HPP) at 600 MPa, 3 min, and 5°C was applied to milk protein concentrate (MPC) samples of 12.5% protein concentration, both in the absence and in the presence of calf chymosin [up to 60 IMCU (international milk-clotting units)/kg of milk] or camel chymosin (up to 45 IMCU/kg of milk). Gel hardness, water-holding capacity, and degree of proteolysis were used to assess network strength and shelf stability. The processing trials and all measurements were conducted in triplicate. Statistical analyses of the data were performed by ANOVA, at a 95% confidence level. After HPP treatment, we observed significant structural changes for all samples. Pressurization of MPC, with or without chymosin addition, led to extensive protein aggregation and network formation. The strength of HPP-created milk protein gels without chymosin addition, as measured by the elastic modulus (G'), had a value of 2,242 Pa. The value of G' increased with increasing chymosin concentration, reaching as high as 4,800 Pa for samples with 45 IMCU/kg of camel chymosin. During 4 wk of refrigerated storage, the HPP and chymosin MPC gels maintained higher gel hardness and better structural stability compared with HPP only (no chymosin) MPC gels. The water-holding capacity of the gels without chymosin remained at 100% during 28 d of refrigerated storage. The HPP and chymosin MPC gels had a lower water-holding capacity (91-94%) than the HPP-only counterparts, but their water-holding capacity did not decrease during storage. Overall, these findings demonstrate that controlled, fast structural modification of high-concentration protein systems can be obtained by HPP-assisted enzymatic treatment, and the created gels have a strong, stable network. This study provides insights into the possibility of using HPP for the development of milk-protein-based products with novel structures and textures and long refrigerated shelf life, along with the built-in safety imparted by the HPP treatment.

Titanium Nanopillar Arrays Functioning as Electron Transporting Layers for Efficient, Anti-Aging Perovskite Solar Cells

Electron transporting layers (ETLs), required to be optically transparent in perovskite solar cells (PSCs) having regular structures, possess a determinant effect on electron extraction and collection. Metal oxides (e.g., TiO₂ ) have overwhelmingly served as ETLs, but usually have low electron mobility (μ_e  < 10^-2  cm² V^-1 s^-1 ) not favorable for photovoltaic conversion. Here, metal oxides are replaced with metals (e.g., Ti with μ_e  ≈ 294 cm² V^-1 s^-1 ) that are sculptured via glancing angle deposition to be a close-packed nanopillar array (NaPA), which vertically protrudes on a transparent electrode to obtain sufficient optical transmission for light harvesting in perovskite. Ti NaPAs, whose rough surfaces are passivated with 5 nm thick TiO₂ (i.e., Ti NaPAs@TiO₂ ) to suppress exciton recombination, lead to the champion power conversion efficiency (PCE) of 18.89% that is superior to that of MAPbI₃ PSCs without Ti NaPAs@TiO₂ or containing TiO₂ NaPAs@TiO₂ , owing to high surface wettability, high μ_e , and relatively low work function of Ti. Furthermore, Ti NaPAs@TiO₂ effectively prevents the decomposition of MAPbI₃ to achieve long-term shelf stability whereby 50-day aging only causes 15% PCE degradation. This work paves the way toward widening the material spectrum, from semiconductors to metals, to generate a diverse range of ETLs for producing efficient optoelectronic devices with long-term shelf stability.

Synergistic Optimization Enables Large-Area Flexible Organic Solar Cells to Maintain over 98% PCE of the Small-Area Rigid Devices

Slot-die coating is generally regarded as the most effective large-scale methodology for the fabrication of organic solar cells (OSCs). However, the corresponding device performance significantly lags behind spin-coated devices. Herein, the active layer morphology, flexible substrate properties, and the processing temperature are optimized synergistically to obtain high power conversion efficiency (PCE) for both the flexible single cells and the modules. As a result, the 1 cm² flexible devices produce an excellent PCE of 12.16% as compared to 12.37% for the spin-coated small-area (0.04 cm² ) rigid devices. Likewise, for modules with an area of 25 cm² , an extraordinary PCE of 10.09% is observed. Hence, efficiency losses associated with the upscaling are significantly reduced by the synergistic optimization. Moreover, after 1000 bending cycles at a bending radius of 10 mm, the flexible devices still produce over 99% of their initial PCE, whereas after being stored for over 6000 h in a glove box, the PCE reaches 103% of its initial value, indicating excellent device flexibility as well as superior shelf stability. These results, thus, are a promising confirmation the great potential for upscaling of large-area OSCs in the near future.

Shelf-Stable Quantum-Dot Light-Emitting Diodes with High Operational Performance

Quantum-dot light-emitting diodes (QLEDs) promise a new generation of high-performance, large-area, and cost-effective electroluminescent devices for both display and solid-state lighting technologies. However, a positive ageing process is generally required to improve device performance for state-of-the-art QLEDs. Here, it is revealed that the in situ reactions induced by organic acids in the commonly used encapsulation acrylic resin lead to positive ageing and, most importantly, the progression of in situ reactions inevitably results in negative ageing, i.e., deterioration of device performance after long-term shelf storage. In-depth mechanism studies focusing on the correlations between the in situ chemical reactions and the shelf-ageing behaviors of QLEDs inspire the design of an electron-transporting bilayer, which delivers both improved electrical conductivity and suppressed interfacial exciton quenching. This material innovation enables red QLEDs exhibiting neglectable changes of external quantum efficiency (>20.0%) and ultralong operational lifetime (T₉₅ : 5500 h at 1000 nits) after storage for 180 days. This work provides design principles for oxide electron-transporting layers to realize shelf-stable and high-operational-performance QLEDs, representing a new starting point for both fundamental studies and practical applications.

Design and shelf stability assessment of bacterial agents for simultaneous removal of methane and odors

Two types of solid bacterial agents for the simultaneous removal of methane and odor were designed using humic soil (De-MO-1) and the mixture of humic soil and tobermolite (De-MO-2) as biocarriers. The bacterial consortium, having the removability of methane and dimethyl sulfide (DMS), was immobilized in the biocarriers, and then stored at room temperature for 375 days without additional treatment. Although the lag period, of which the incubation time required for removing methane and DMS, tended to increase over the storage period, the removability of methane and DMS was maintained during 375 days in both bacterial agents. Key bacteria associated with the removal of methane and odors (Streptomyces, Promicromonospora, Paracoccus, Lysobacter, Sphingopyxis and Methylosystis) could keep their abundance during the storage period. The richness and evenness values of the bacterial communities in De-MO-1 and De-MO-2 ranged 4.89 ∼ 6.50 and 0.89 ∼ 0.98, respectively, indicating that high bacterial diversity was maintained during the storage period. The results suggest that De-MO-1 and De-MO-2, designed for the simultaneous removal of methane and odors, had shelf stabilities over one year.

Effect of Gaeddongssuk (Artemisia annua L.) Powder on Quality and Shelf Stability of Emulsion Sausages during Refrigerated Storage

The objective of this study was to evaluate effects of Gaeddongssuk powder (GP) on quality characteristics and shelf stability of emulsion sausages during storage. Proximate composition properties showed no significant differences in all treatment (p>0.05). Control showed the highest cooking loss while the treatment with GP showed decreased cooking loss depending on increasing GP content (p<0.05). Apparent viscosity of batter was increased as the amount of GP increased, whereas hardness of emulsion sausages was decreased with increasing GP level. In sensory evaluation, emulsion sausage with 0.1% GP resulted in the highest score in overall acceptability. The pH values of all treatments decreased at the early storage stage, followed by gradual increase. The lightness and redness of treatments were decreased when the level of GP was increased. However, the yellowness of sausages with GP were higher than that of control (p<0.05). The addition of GP inhibited lipid oxidation of emulsion sausages during storage depending on its level. The aerobic bacteria population and VBN was unaffected by addition of GP during the storage (p>0.05). Therefore, Gaeddongssuk powder up to 0.1% has a potential as a natural antioxidant for meat products because it can inhibit lipid oxidation of sausages without decreasing their sensory properties.

Nutritional composition, quality, and shelf stability of processed Ruspolia nitidula (edible grasshoppers)

The nutritional and commercial potential of the edible grasshopper (Ruspolia nitidula, nsenene in Luganda), a delicacy in Uganda and many East African tribes, is limited by a short shelf life and unverified nutritional value. This research established that R. nitidula is nutritious with 36–40% protein, 41–43% fat, 2.5–3.2% carbohydrate, 2.6–3.9% ash, 11.0–14.5% dietary fiber, and 900–2300 μg/100 g total carotenoids on a dry matter basis. Sautéing was the most preferred processing method resulting in grasshoppers with a notably better aroma and flavor. After 12 weeks of storage at room temperature, processed and vacuum packed, ready‐to‐eat grasshoppers maintained their edible quality with an acid value of 3.2 mg KOH/g, a total plate count of log 1.8 cfu/g, and an overall acceptability of 6.7–7.2 on a 9‐point hedonic scale. Further research is required for extending the shelf stability beyond 12 weeks and characterizing the profile of major nutrients.

Temperature dependency of shelf and thermal stabilities of anthocyanins from corn distillers' dried grains with solubles in different ethanol extracts and a commercially available beverage

The objective was to determine the shelf and thermal stabilities of anthocyanins from distillers' dried grains with solubles (DDGS) extracted with different ethanol concentrations as well as a semi-purified Maiz Morado (purple corn) anthocyanin extract added to a commercially available beverage. Storage for 6 weeks of DDGS showed an overall reduction of anthocyanins from 6.8 to 73.7%. In DDGS, an ethanol increase from 0 to 25% resulted in less sensitivity of anthocyanin to temperature changes. Acylation resulted in faster degradation and higher reaction rate constants than their corresponding non-acylated forms. Anthocyanin changes were accompanied by an overall increase in lightness and a decrease in redness. Storage of beverage for 12 weeks at 4 °C resulted in a 25.5% reduction of anthocyanin. Results have important implications in selecting colored corn as an economical source of food colorants.

Development and acceptability of a novel milk-free soybean-maize-sorghum ready-to-use therapeutic food (SMS-RUTF) based on industrial extrusion cooking process

Peanut milk-based ready-to-use therapeutic food (P-RUTF) primarily used to treat severe acute malnutrition at community setting is expensive. We developed an alternative milk-free soybean-maize-sorghum-based RUTF (SMS-RUTF) using locally grown ingredients that have the potential to support local economy and reduce the cost of RUTF. We describe the production process and results of acceptability of the new product. Acceptability and tolerance of SMS-RUTF was compared with P-RUTF among 45 children aged 4-11 years old based on a cross-over design. Each child consumed 250 g RUTF for 10 days followed by a five-day washout period and a subsequent 10-day period on the second RUTF. The SMS-RUTF was as acceptable as the P-RUTF among normal children aged 4-11 years of age with no associated adverse effects. SMS-RUTF was stable for at least 12 months without detectable microbiological or chemical deterioration. The major challenge encountered in SMS-RUTF development was the difficulty to accurately determine key nutrient composition due to its high oil content. Use of diversified locally available ingredients to produce RUTF is feasible. The SMS-RUTF meets expected standards and is acceptable to children aged 4-11 months old. Effectiveness and cost-effectiveness of SMS-RUTF is required.