Freeze-dried Research Articles

Physicochemical Characteristics of 'Wushan Plum' Subjected to Three Drying Methods.

In this study, the effects of hot air drying (HAD), freeze-drying (FD), and air-impingement jet drying (JD) on the physicochemical characteristics of 'Wushan plum' were analyzed. The results indicated three drying methods affected the browning, ascorbic acids, phenolic compounds, and antioxidant activities. The ascorbic acid content in HAD, FD, and JD samples was1.75±0.38, 5.88±0.56, and 4.73±0.75 mg/100 g, respectively, and the content of total phenolic compounds was 2.76±0.10, 3.05±0.04, and 2.83±0.24 mg/g, respectively. HAD samples had the lowest antioxidant activities as determined by DPPH·, ABTS+·, and FRAP assays. In addition, 11 phenolic compounds in 'Wushan plum' were quantified by UPLC-QqQ-MS/MS. The results showed that quercetin glycoside was the main compound, and its content was significantly reduced by these three drying methods. In all, this result indicated that JD would be a good choice for dying 'Wushan plum' considering the drying time, drying efficiency, and the integrated quality of the dried sample.

Freeze-dried fecal microorganisms as an effective biomaterial for the treatment of calves suffering from diarrhea.

Fecal microbiota transplantation (FMT) is a therapeutic modality for treating neonatal calf diarrhea. Several practical barriers, including donor selection, fecal collection, and a limited timeframe for FMT, are the main constraints to using fresh feces for implementing on-farm FMT. We report the utility of FMT with pretreated ready-to-use frozen (F) or freeze-dried (FD) microorganisms for treating calf diarrhea. In total, 19 FMT (F-FMT, n = 10 and FD-FMT, n = 9) treatments were conducted. Both FMT treatments were 100% clinically effective; however, multi-omics analysis showed that FD-FMT was superior to F-FMT. Machine learning analysis with SourceTracker confirmed that donor microbiota was retained four times better in the recipient calves treated with FD-FMT than F-FMT. A predictive model based on receiver operating characteristic curve analysis and area under the curve showed that FD-FMT was more discriminative than F-FMT of the observed changes in microbiota and metabolites during disease recovery. These results provide new insights into establishing methods for preparing fecal microorganisms to increase the quality of FMT in animals and may contribute to FMT in humans.

Antioxidant Valorization of PLE Extracts from Macroalgae (Cladophora glomerata): In Vitro Assessment of Nanoemulsions Against Oxidative Stress

Driven by a growing global interest in natural products, macroalgae have emerged as a prime source for nutraceuticals and pharmaceutical applications. In the current research, the effect of oven-drying (OD) and freeze-drying (FD), as well as the pressurized liquid extraction (PLE) conditions, were investigated in relation to the polyphenols, flavonoids, carotenoids, chlorophylls, and tocochromanols levels in Cladophora glomerata extracts. The ethanol–water extracts (1:1) obtained with PLE-150 °C from macroalgae oven-dried (OD)-80 °C displayed the highest total polyphenol content (TPC) and total flavonoid contents (TFCs), reaching 29.62 mg GAE/g and 5.92 mg QE/g. Aqueous extracts using PLE-200 °C were also an excellent environmentally friendly option for TPC and TFC isolation, which were the main factors accounting for the ABTS, DPPH, and FRAP antioxidant activity of the extracts. The remarkable effects of drying conditions positively affect the carotenoids, chlorophyll α-tocopherol, and α-tocotrienol levels from extracts showing 1.3–6 times higher amounts in extracts of Cladophora glomerata OD at 80 °C compared with other research approaches. Nanotechnology approaches allowed the formulation of antioxidant-loaded nanoemulsions from Cladophora glomerata extracts, providing stability and a great internalization rate that ameliorates to 85% the ROS levels, attenuating the oxidative stress induced by H2O2 in J774.1 macrophage cell line.

Pharmaceutical Residues in Fishes and Macro Invertebrates around the Wastewater Treatment Plant Site at the University Teaching Hospital of Yaoundé, Cameroon

Introduction: Hospital effluents are one of the main sources of dissemination of pharmaceutical residues in hydro system. Worldwide, analyses of these effluents have revealed the presence of various pharmaceuticals. Very few studies assessing the contamination of solid matrices by pharmaceutical residues have been carried out in Africa, specifically in Cameroon. Objectives: The study aimed to detect pharmaceutical residues in solid environmental matrices at sites around the discharge of the effluent from the Yaoundé University Teaching Hospital. Methods: Four hundred and fifty-nine (459) macro invertebrates and twenty (20) Nile tilapia were collected in three sampling sites before and beyond the wastewater treatment plant of the Yaoundé University Teaching Hospital. The specimens were conserved in a cooler prior to freeze drying and grinding. The powders were sent for analysis at the Sefako Makgatho Health Sciences University in South Africa. The analysis was carried out using an ultra-high-performance liquid chromatography coupled with a triple quadrupole tandem mass spectrometer. Results: A total of ninety-nine pharmaceutical residues related to seventeen pharmacological classes were detected in all samples of macro invertebrates (72) and Nile tilapia (55 for fish viscera and 58 for fish flesh) collected. Antibiotics were the most represented (23.2 %), followed by anti-inflammatory (18.2 %), and anti-parasitics (9.1 %). More than half (53.6 %) of the drug residues detected in the fish samples were of the anti-inflammatory (21,71 %), antihypertensive (17,67 %) and antibiotic (13,13 %) classes. The number of drug residues detected in the macroinvertebrates before the treatment plant (41) was smaller than those detected after the treatment plant (67). Conclusion: Five therapeutic classes (antibiotics, anti-inflammatories, antihypertensive, antiparasitics and hormones) were mostly represented.These results are in line with the importance of considering diet of fishes and/or humans as an exposure pathway based on the great similarity in pharmaceutical composition between macroinvertebrates and Nile tilapia.

Probiotication of Plum Pulp and Conditions Effects Freeze-Drying in Cell Viability, Functional Properties and Antioxidant Activity

This study investigated the effects of fermenting plum pulp with Bifidobacterium animalis ssp. lactis (BAL) on its physicochemical and bioactive properties, as well as the optimization of the freeze-drying (FD) process to develop a fruit-based probiotic delivery system. Fermentation significantly reduced the pH and total acidity of the pulp, achieving a cell viability of 11 log CFU/mL. The FD process was optimized using a factorial design, with maltodextrin concentration (3, 5, and 7%) and freezing temperature (−150, −100, and −50 °C) as variables. The P2 experiment, which used 7% maltodextrin and freezing at −150 °C, showed the best results in terms of yield (25.67%), cell viability (8 log CFU/g), and probiotic survival rate (97.66%). Samples P5, P6, and P7, prepared with 5% maltodextrin and freezing at −100 °C, exhibited the highest levels of bioactive compounds and antioxidant activity (p < 0.05). During 28 days of storage, all samples maintained cell viability without significant logarithmic reduction. In summary, probiotic plum powders offer an excellent plant-based alternative for probiotic consumption, providing safe levels of beneficial bacteria and bioactive compounds with antioxidant action, meeting health and nutrition needs.

FORMULATION, CHARACTERIZATION AND OPTIMIZATION OF PLGA-CHITOSAN-LOADED FATTY ACID SCAFFOLDS FOR THE TREATMENT OF DIABETIC WOUNDS

Objective: The objective of the current research to formulate Eicosapentanoic Acid/Decosahexanoic Acid (EPA/DHA)incorporated into Chitosan (CS)and Poly-Lactic-Glycolic Acid (PLGA), nanoparticles composite scaffolds to the accelerated diabetic wound healing. The main focus of this present research is to evaluate and develop the chitosan–PLGA biodegradable polymer scaffolds loaded with long-chain omega-3 Polyunsaturated Fatty Acids (PUFA’s) (EPA/DHA). Methods: Nano scaffolds were prepared by solvent evaporation method loaded with CS-PLGA, EPA and DHA to treat diabetic wounds at targeted site as pharmacotherapeutically. Upon investigation, the developed biodegradable crosslinked scaffold possesses matrix degradation, optimal porosity, prolonged drug release action than the non-cross linked scaffold. The prepared formulation containing CS-PLGA loaded with EPA/DHA were formulated as nanoscaffold for wound topical applications was carried out by using freeze drying process. Results: The prepared CS-PLGA nano scaffolds were optimized and evaluated for physicochemical properties, dynamic light scattering with a particle size of 248 nm and zeta of-24mVand Scanning Electron Microscopy (SEM) were found to be spherical. In addition, the optical properties of EPA/DHA and PLGA, along with CS, can be compared by examining their absorption and wavelength (nm) using UV-visible spectroscopy. The structural and functional groups of the prepared end products were characterized by Fourier-Transformed Infrared Spectroscopy (FT-IR) has shown good compatibility with excipients and nanoformulaton, in vitro drug release studies done by using dialysis bag membrane results find that first-order Higuchi model was followed showing 20% release in first 0.2 h. MTT(3-(4,5-dimethylthiazolyl)-2,5-diphenyltetrazolium bromide) assay was carried out and it showed that both crosslinked and non-crosslinked scaffolds(110 and 120%) improved cell growth when compared to control (100%). Conclusion: Finally, the results showed that the PLGA, CS nanoscaffolds containing 98% of PUFA’s (EPA/DHA) have increased in proinflammatory cytokines production at the particular wound site and thus accelerated healing activity, depending on the pre-clinical studies have trespassed, the therapeutic potential to penetrating at wound site. The optimized nanoformulation could be a better formulation for targeting and treatment of diabetic wounds at an optimal ratio.

Analysis of the influence of different drying processes on the quality attributes of orange peel

The present research aimed to assess the effect of different drying processes on kinetics, antioxidant content and activity, texture, colour, morphology, and β-carotene content of orange peel (OP). The utilization of microwave drying resulted in a notable increase in the rate of evaporation of water present in the orange peel. This process facilitated the release of bound polyphenols. The OP dried at 600 W exhibited the highest total phenolic compound (24.65 mg GAE/g) and total flavonoid compound (11.73 mg QE/g), as observed in the recorded data. The total antioxidant value exhibited a decrease at both elevated and reduced levels of microwave power compared to raw OP. The study found that the drying model proposed by the Weibull model exhibited the most optimal fit, as evidenced by a low SSerror (1.6 × 10−3-16.12 × 10−3), RMSE (0.02–0.05) and high R2 (0.99–1.00). Among dried products, high hardness (30.92 ± 1.26 N), fracturability (28.31 ± 1.22 N), and lightness (74.01 ± 0.38) were observed in freeze-dried (FD) OP. The browning index was high in microwave drying at 180 W (MWD 180 W), and tray drying (TD) which also produced more vibrant colours, as observed in their high chroma value. The high performance liquid chromatography (HPLC) showed that the retention of β-carotene was observed highest in FD (0.057 ± 0.003 mg/g) and lowest in TD (0.032 ± 0.002 mg/g). The morphological study revealed small-sized particles in high-temperature drying methods (MWD 900 W and TD). Large pores and frequent cracking were observed in microwave drying compared to FD. Four clusters are formed in Principal component analysis (PCA) loading of Fourier transform infrared (FTIR) spectra based on their similar characteristics as found in FTIR. Antioxidant content and texture are closely related to the chemical moieties, as observed in PCA.

Engineering Injectable and Highly Interconnected Porous Silk Fibroin Microspheres for Tissue Regeneration.

Injectable porous microspheres represent a promising therapeutic platform for cell delivery, drug delivery, and tissue regeneration. Yet, the engineering of silk fibroin microspheres with a highly interconnected porous structure remains an unsolved challenge. In this study, a simple and efficient method is developed that does not require the use of organic solvents to prepare silk fibroin microspheres with a predictable structure. Through extensive screening, the addition of glucose is found to direct the formation of a highly interconnected porous structure from the interior to the surface of silk fibroin microspheres. Compared to silk fibroin microspheres (SF microspheres) produced through a combination of electro-spray, cryopreservation, and freeze drying, silk fibroin-glucose microspheres (SF-Glu microspheres) demonstrates enhanced capabilities in promoting cell adhesion and proliferation in vitro. Both SF-Glu and SF microspheres exhibit the capacity to maintain the sustained release kinetics of the loaded model drug. Furthermore, SF-Glu microspheres facilitate the recruitment of endogenous cells, capillary migration, and macrophage phenotype switch following subcutaneous injection in the rats. This study opens a new avenue for the construction of porous silk fibroin microspheres, which could lead to a broader range of applications in regenerative medicine.

A Comparison of the Impacts of Different Drying Methods on the Volatile Organic Compounds in Ginseng

Ginseng (Panax ginseng C. A. Meyer) is a valuable plant resource which has been used for centuries as both food and traditional Chinese medicine. It is popular in health research and markets globally. Fresh ginseng has a high moisture content and is prone to mold and rot, reducing its nutritional value without proper preservation. Drying treatments are effective for maintaining the beneficial properties of ginseng post-harvest. In this study, we investigated the effects of natural air drying (ND), hot-air drying (HAD), vacuum drying (VD), microwave vacuum drying (MVD), and vacuum freeze drying (VFD) on volatile organic compounds (VOCs) in ginseng. The results showed that the MVD time was the shortest, followed by the VFD, VD, and HAD times, whereas the ND time was the longest, but the VFD is the most beneficial to the appearance and color retention of ginseng. A total of 72 VOCs were obtained and 68 VOCs were identified using the five drying methods based on gas chromatography–ion mobility spectrometry (GC-IMS) technology, including 23 aldehydes, 19 alkenes, 10 alcohols, 10 ketones, 4 esters, 1 furan, and 1 pyrazine, and the ND method was the best for retaining VOCs. GC-IMS fingerprints, principal component analysis (PCA), Euclidean distance analysis, partial least squares discriminant analysis (PLS-DA), and cluster analysis (CA) can distinguish ginseng from different drying methods. A total of 29 VOCs can be used as the main characteristic markers of different drying methods in ginseng. Overall, our findings provide scientific theoretical guidance for optimizing ginseng’s drying methods, aromatic health effects, and flavor quality research.

Antioxidant Properties of Freeze Dried Mix Fruits and Vegetables Product ‘Miss Freezy’ Using Lyophilization Method

Background: The proper processing of fruits and vegetable-based food products will improve appearance, taste, bioactivities, and preservation. Freeze-dried (FD) or lyophilization of foods extends shelf life and preserves food's nutritional value and bioactivities. The objective of this study is to compare the antioxidant properties, nutritional value, and vitamins of fresh fruit-vegetables and the combined FD product. Methods: A combination of fruits (mango, papaya, star-fruit, guava, banana, bengkuang), and vegetables (cucumber), called “Miss Freezy” were cleaned with an ozonizer and processed using the lyophilization method. The antioxidant activities measured included 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-Diphenyl-1-picrylhydrazyl (DPPH), and Hydrogen Peroxide (H2O2) assay. While the proximate analysis measured was the determination of water content, ash content, fat content, protein and carbohydrate content, and vitamin C. Results: The value of antioxidant activity in fruit-vegetable combination FD products was higher than in fresh fruit. The median inhibition concentration (IC50) of DPPH, ABTS, and H2O2 scavenging activities were guava 48.74 µg/ml, guava 128.39 µg/ml, and banana 155.55 µg/ml, respectively. The results showed that the water content of fresh fruits, and vegetables was greater than FD products and inversely proportional to the level of ash, fat, protein, carbohydrates, and vitamin C lower than FD products. Conclusions: Based on the results of antioxidant activities, proximate analysis and vitamin C of the FD product was higher than fresh fruits and vegetables. The FD fruit-vegetable combination product can be used as an alternative snack product that is practical and healthy.

Effects of different drying methods on the nutritional components, microstructure, and metabolomic profile of Spirulina maxima

Spirulina maxima (S. maxima) is considered a potential solution to address the issue of human food security. In this study, three drying methods were employed: spray drying (SD), freeze drying (FD), and vacuum drying (VD), to process fresh S. maxima (FS). A comprehensive nutritional evaluation was conducted using principal component analysis and cluster analysis, along with an untargeted metabolomics study. The results indicated that after SD, FD, and VD treatments, the phycocyanin content decreased by 23 %, 9 %, and 80 %, respectively, compared to that of the FS. The polysaccharide content also significantly decreased by 36 %, 33 %, and 67 %, respectively. Comprehensive analysis showed that SD resulted in the least loss of nutritional indicators in S. maxima. Further metabolomics analysis revealed that prolonged exposure to high temperatures can lead to metabolic disruptions in 2-oxocarboxylic acid metabolism, purine metabolism, amino acid biosynthesis, and starch and sucrose metabolism. Additionally, the levels of coproporphyrin I and coproporphyrin III increased which ultimately led to a decrease in chlorophyll and phycocyanin contents. Therefore, VD resulted in the poorest quality of S. maxima. This study provided a theoretical basis for the quality assessment of S. maxima in response to drying.

Fabrication and optimization of ultra-long stable microencapsulated chlorophyll using combinations of wall material via response surface methodology

Nowadays, the need to use natural pigments instead of artificial colorants in food has increased due to health risks. Chlorophyll is a natural colorant with antioxidant properties. Chlorophyll is a natural pigment with superior antioxidant properties. However, this pigment is unstable in the different conditions of food processing. To increase the stability of chlorophyll extracted from Ulva intestinalis algae, encapsulation of chlorophyll with maltodextrin (MD) and whey protein isolate (WPI) carriers by two drying methods including spray drying and freeze drying was achieved. The optimum combination of wall and core materials to achieve the highest response including encapsulation efficiency (EE) and chlorophyll content (CC) was obtained by response surface methodology and central composite design. The optimal chlorophyll microcapsule (Chl-M) obtained was chosen for subsequent tests containing solubility, moisture content, and antioxidant properties. The results showed that the highest EE and CC were 90.27 ± 0.21%, 55.36 ± 0.36 μg/mL, and 90.46 ± 0.62%, 85.85 ± 0.43 μg/mL, respectively in SD and FD. The microcapsules produced by the freeze dryer (FD) had higher antioxidant activity (79.1 ± 0.24) than the microcapsules produced by the spray dryer (SD) (67.5 ± 0.16). The highest solubility (95.32%) and the lowest moisture content (3.7 ± 0.05) were related to the SD. Freeze drying method (FDM) had the highest EE (91.2%), CC (89.67 μg/mL), and antioxidant properties (79.1%). It is hoped that the encapsulated chlorophyll can be used as a health-promoting food color additive in the food industry.

Effect of Extraction Processes on the Physicochemical and Functional Properties of Protein-Rich Extracts from the Red Seaweed Pyropia Seriata (Nori)

This study examined the physicochemical and techno-functional properties of protein extracts from the red seaweed (Pyropia seriata). The extraction processes involved variations of some of the following steps: alkaline treatment, milling, freeze drying, neutralisation, heating, and concentration. The extracts had total amino acid contents ranging between 40–55% of the powders with essential amino acids comprising 25–30% of the powders. The extracts were particularly abundant in aspartic acid and limited in the essential sulphur amino acids. The molecular weight (MW) distribution of the proteins within the extracts ranged from <10 to 50 kDa. All the extracts were soluble, with a solubility of 65–100% depending on the final pH of the solution. The extracts had significant foaming-producing and emulsifying potential. The foaming stability ranged between 75–91% for solutions between pH 7 to 11 and less than 75% for solutions with pH of 5 or 3. Alkaline treatment significantly improved foaming capacity (120-160%). A similar effect was also observed for emulsifying activity (0.29–0.51) and emulsifying stability (15–40%). Milling enhanced the emulsifying potential and decreased the mg of amino acids per g powder. Neutralisation with hydrochloric acid instead of citric acid and subsequent heating and concentration showed minimal effect on the properties of the extracts and decreased the mg amino acids per g powder. This research highlights the potential of Pyropia seriata as a source of soluble alternative protein for food applications.

The Impact of Drying Techniques on Stabilizing Microencapsulated Astaxanthin From Shrimp Shells: A Comparative Study of Spray Drying Versus Freeze Drying

ABSTRACTThe research aimed to study how different drying methods (spray and freeze drying) affect the release kinetics of microencapsulated astaxanthin in various environmental conditions. Shrimp shell extract containing astaxanthin was encapsulated using different wall components (maltodextrin with different dextrose equivalents and modified starch) via a simplex lattice mixture design. The encapsulated extract was then subjected to storage at different temperatures (25°C ± 2°C and 2°C ± 4°C) and humidity conditions (52% ± 2% and 75% ± 2%), as well as exposure to UV light (four 15 W lamps, 254 nm, for 10 h). The release kinetics of astaxanthin were analyzed using various models (page, Newton Korsmeyer–Peppas model, Modified Henderson and Pabis, Diffusion approach, and Two‐term exponential). The evaluation results of correlation coefficient (R2), root mean square deviation (RMSE), and mean absolute percentage error (MAPE) values of different models showed that the astaxanthin degradation followed a two‐term exponential kinetics in both types of microcapsules. Astaxanthin degradation increased with higher temperatures, humidity, and UV light exposure. However, microcapsules with equal wall compound ratios exhibited better preservation of astaxanthin. The study also emphasized the significance of optimizing storage conditions and wall materials for microencapsulated astaxanthin, as well as the utility of the two‐term exponential model in enhancing stability and shelf life.

Ultra-lightweight asymmetric hierarchical porous structure for high-efficiency absorption-dominated electromagnetic interference shielding

In this work, ultra-lightweight composite aerogels with a hierarchical pore structure consisting of hollow Fe3O4 microspheres (∼250 nm), hollow MXene microspheres (∼580 nm) and pores (10∼40 μm) in polyimide (PI) aerogel are developed through directional freezing, followed by freeze drying and thermal annealing. The composite aerogels exhibit a distinct asymmetric structure, with a top Fe3O4/PI aerogel layer designed for impedance matching and a bottom MXene/PI aerogel layer aimed at enhancing attenuation. This deliberate structure design not only reduces the density of the composite aerogels but also greatly enhances their absorption of electromagnetic waves. The composite aerogel demonstrates an impressive X-band EMI SE of 69.7 dB, a remarkable absorption coefficient (A) of 0.73, and an excellent surface-specific SE (SE divided by material density and thickness) of 13352 dB cm2 g-1, achieved at a density of just 0.034 g/cm³. Moreover, the composite aerogel exhibits outstanding stability in compression and shielding performance. Following 100 cycles of compression, the compressive strength remains at 94.9% of the initial compressive strength (98 kPa), and its EMI SE maintains 68.5 dB with a retention rate of 98.2%. Additionally, the composite aerogel presents outstanding thermal insulation (0.046 W m-1 K-1) and thermal resistance (initial decomposition temperature > 500 °C). This work provides novel insights into the design and fabrication of ultra-lightweight and absorption-dominated EMI shielding materials.

Drying of Red Chili Pepper (Capsicum annuum L.): Process Kinetics, Color Changes, Carotenoid Content and Phenolic Profile.

Studies were conducted focusing on the drying of chili pepper fruits (Capsicum annuum L.), cultivar Cyklon, using convective (AD), convective-microwave (AMD), vacuum (VD), and freeze-drying (FD) methods. The influence of the drying method and temperature on the kinetics of the process and selected quality attributes of the dried product were evaluated. It was demonstrated that the Midilli model best described the drying kinetics for all methods across the entire measurement range. FD and VD produced dried products with the highest brightness and the greatest value of the a* color parameter. The lowest b* color parameter was observed for the product dried using FD at 40 °C, while the highest b* value was noted for samples dried using AMD (100 W) at 60 °C. The highest carotenoid retention was achieved with the FD method at 40 °C, while the lowest carotenoid content was found in the product obtained using the AMD method (100 W) at 60 °C. The smallest losses of capsaicinoids were observed after FD drying at 40 °C, while the largest were found for AMD (100 W) at 60 °C. The analysis of chili pepper fruit extracts revealed the quantitative composition of 12 main phenolic compounds using the UHPLC-UV method. The highest polyphenol content was obtained with FD, while the lowest total polyphenol content was recorded after AD. Regardless of temperature, the total flavonoid content was highest in extracts from FD products, and the lowest flavonoid content was found after AMD at 100 W. For all drying methods analyzed, the total flavonoid content in the pepper extracts decreased with increasing temperature.

The Ontogeny and Dietary Differences in Queen and Worker Castes of Honey Bee (Apis cerana cerana)

The honey bee Apis cerana cerana (A. c. cerana), a subspecies of Apis cerana, is endemic in China and possesses a valuable ecological niche. Understanding the ways to protect this honey bee’s populations is crucial, but this topic has been understudied. For the efficient utilization of beekeeping and pollination, there is a need to explore its biology and management practices. In light of this, the current study was carried out to investigate the ontogeny and dietary differences in the queen and worker castes of the A. c. cerana honey bee. This article presents, supplemented by reference images, a detailed description of the life history of A. c. cerana queens and workers. Additionally, this study investigated the nutritional differences between royal jelly (RJ) and worker jelly (WJ) at various larval ages. The contents of the moisture, crude protein, and amino acids in RJ and WJ were determined via freeze drying, Kjeldahl nitrogen determination, and ultra-high performance liquid chromatography. The results highlight significant variations in the moisture content, crude protein concentration, and amino acid concentration between RJ and WJ. The results offer theoretical support for ex situ artificial rearing practices of A. c. cerana.

Dielectric drying of black soldier fly larvae (Hermetia illucens): impact on microbiological product quality, safety and stability

Abstract Along with the increasing scale of industrial production of insects as food and feed, the need for processing methods applicable on large scale is rising within the insect sector. One important processing technology in this context is drying, which aims at stabilising the quality of the insects. This study investigated the impact of dielectric drying technologies, specifically microwave (μW) and radio frequency (RF) drying, on the microbiological quality, safety, and stability of black soldier fly (BSF) larvae in comparison to the traditional methods oven drying and freeze drying. Before, during and after subjecting a large batch of blanched BSF larvae to the four drying technologies, their water activity and moisture content as well as general microbial and pathogen counts were assessed. Dielectric drying effectively reduced water activity, thus enhancing product stability. Microbiological analyses revealed the efficacy of blanching in microbial reduction, with dielectric (especially RF) drying further contributing to these reductions. The results, however, do not conclusively support nonthermal microbial inactivation through dielectric treatment. Specific analyses targeting foodborne pathogens indicated the absence of most selected bacterial pathogens, except for (presumptive) Bacillus cereus. This pathogen was detected in a few samples but remained below safety thresholds and was effectively eliminated by dielectric drying. Finally, a shelf life stability evaluation showed minimal changes in dielectrically dried BSF larvae over six months, indicating a microbiologically stable product. In conclusion, dielectric drying technologies can retain or even improve the microbiological quality and stability of BSF larvae in the insect industry and can be considered as valuable and more efficient (time, energy consumption) alternatives to oven and freeze drying.

Shaping the Physicochemical and Health-Promoting Properties of Carrot Snacks Produced by Microwave-Vacuum Drying with Preliminary Thermal and Enriching Treatment.

This study analyzed the effects of thermal pre-treatments such as convective drying (P-CD), water (BL_W), and microwave blanching (M_BL) and osmotic enrichment pre-treatments with juices from pomegranate (PG), chokeberry (CH), and sea buckthorn (SB) on microwave-vacuum-dried (MVD) carrot properties. Convective drying (CD) and freeze-drying (FD) were used as a comparative method. The dry matter content and water activity of MVD carrots were varied, but in many cases, the values were comparable to those of FD-dried carrots. Pre-enrichment in CH juice significantly reduced the values of the color parameters L*, a*, and b*, regardless of the drying method. The smallest changes were observed in microwave pre-blanching (M_BL). The lowest loss in carotenoid content was observed in CD-dried carrots (14-34 mg/100 g d.m.). Blanching and enrichment in SB juice allowed significant retention of these compounds. As a result of drying carrots, the total phenolic content (TPC) increased. Compared to the raw material, the TPC content in dried carrots increased 3-9 times. Drying using the FD and MVD methods gave a similar effect of increasing the TPC content, including a greater effect after enrichment in CH juice. The highest average antioxidant activity against the DPPH• and ABTS•+ radicals was recorded for FD-dried carrots (6.9 and 30.0 mg Trolox/g d.m.). SB juice contributed to a significant increase in the total vitamin C content, even by 89.1%, compared to raw carrots. Applying osmotic pre-enrichment in PG juice increased the sugar content in dried FD and CD samples by 37.4-49.9%, and in MVD by 21-59%.

Microstructural Modification and Sorption Capacity of Green Coffee Beans.

To enhance the pore structure of green coffee beans (GCB) and detect the sorption capacity and extraction characteristics of flavor compounds before roasting, this study employed several methods: hot air drying (HD), freeze-drying (FD), 3-levels short-time heating with puffing (SH1P, SH2P, and SH3P), and 3-levels microwave with puffing (MW45P, MW60P, and MW75P). These methods were applied to GCBs pre-soaked in water for different times. The effects of these treatments on color change, porosity, microstructure, citric acid sorption capacity, and caffeine and chlorogenic acid extraction yield were investigated. Results indicated that, except for GCBs treated with SH1P, SH2P, SH3P, and MW75P, all other modified GCBs showed minimal color change. GCBs treated with MW60P exhibited favorable pore structures. MW60P treatments significantly improved the extraction yield of caffeine and chlorogenic acid. Furthermore, the increased porosity and improved pore size distribution of GCB after MW60P resulted in a significant increase in the sorption of citric acid onto modified GCB. The rate of the sorption reaction followed the pseudo-first-order kinetics. In conclusion, MW60P are effective treatments for enhancing the microstructure of GCB, improving sorption capacity, and improving the extraction yield of flavor compounds.