Evaluation of the water state and protein characteristics of Tibetan pork under the storage conditions of modified atmosphere packaging: Effect of oxygen concentration.

To explore the changes in water status and protein characteristics of Tibetan pork (TP) under modified atmosphere packaging (MAP) with different oxygen concentrations compared to Duroc×Landrace×Yorkshire pork (DLY), the water holding capacity (WHC), water distribution, protein oxidation, and conformation of both types were determined. Results indicate that under MAP, TP pork and DLY pork exhibited higher water retention and lower protein oxidation compared to air packaging. However, with increased oxygen concentration in the MAP, protein oxidation intensified, leading to reduced WHC in the pork. Compared to DLY pork, TP pork in different packaging conditions maintained the integrity of protein secondary and tertiary structures, reducing protein cross-linking aggregation. The lower content of P 3 in the two-dimensional relaxation spectra, shorter T 1 and T 2 relaxation times, and higher proton density suggest better water retention properties in Tibetan pork. These findings support the development of long-distance preservation and transportation technologies for TP pork.

Influence of electrohydrodynamics on the drying characteristics, microstructure and volatile composition of apricot abalone mushroom (Pleurotus eryngii).

The study explored the use of current fluid dynamics drying technology for apricot abalone mushroom, examining how different output voltages (15, 25, and 35 kV) affected drying characteristics, microstructure, and volatile components. Comparisons were made with samples dried using hot air drying (HAD) and natural air drying (AD). Results revealed that HAD had the fastest drying rate at 0.29664(g·h-1). However, apricot abalone mushroom treated with electrohydrodynamic drying (EHD) maintained a color closer to fresh samples, exhibited a 21% increase in the ordered structure of protein secondary structure, a 12.5-fold increase in bound water content, and the most stable cell structure compared to HAD and AD treatments. A total of 83 volatile organic compounds were identified in the apricot abalone mushroom, with alcohols and aldehydes being the most prominent in terms of threshold and relative content, peaking in the 35 kV treatment group. These findings provide both experimental and theoretical insights into applying current fluid dynamics for drying apricot abalone mushroom.

The effect of CaCl2 on water migration, rheological properties, aggregation behavior and protein structure in rapidly salted separated egg yolk plasma and granules.

This research investigated the effects of CaCl2 on the aggregation behavior and protein structure of egg yolk plasma and granules after fast salting. The addition of CaCl2 to the salt solution decreased T23, D [4,3] and the absolute value of the zeta potential by 6.71%, 3.66%, and 3.15%, respectively, while increasing T22 by 15.85% in egg yolk plasma. Moreover, adding CaCl2 also increased the apparent viscosity and G' value of egg yolk plasma. On the other hand, the addition of CaCl2 decreased the T22, T23, D [4,3], and absolute value of the zeta potential of egg yolk granules by 56.53%, 6.71%, 6.02%, and 34.27%, respectively. Furthermore, the addition of CaCl2 increased the number of ß-turns by 51.22%, whereas it decreased the number of ß-sheets by 26.55% in egg yolk plasma protein. The α-helices, ß-turns, and ß-sheets of egg yolk granule protein decreased by 6.58%, 3.58%, and 6.96%, respectively. Additionally, the addition of CaCl2 can increase the degree of λmax redshift in egg yolk plasma and decrease the degree of λmax redshift in egg yolk granules. Overall, the addition of CaCl2 can change the aggregation mode of proteins in egg yolk plasma and granules, improving the quality of salted egg yolk products.

Indirect prediction of the 3D printability of polysaccharide gels using multiple machine learning (ML) models.

In this paper, the capabilities of NIR spectroscopy and LF-NMR data were compared for rapidly predicting the rheological properties of polysaccharide gels and assessing their printability. Seven machine learning (ML) models were established for rheological property prediction based on partial least squares regression (PLSR), support vector regression (SVR), back propagation artificial neural network (BPANN), one-dimensional convolutional neural network (1D CNN), recurrent neural network (RNN), long short-term memory (LSTM), and Transformer. The results showed that among the seven models, the SVR, BPANN, and 1D CNN models based on NIR spectroscopy effectively predicted the rheological parameters of polysaccharide gels, with the highest R2 in the prediction set reaching 0.9796 and the highest RPD reaching 7.0708. For most polysaccharide gels, using the LF-NMR relaxation time distribution curves provided better predictions of rheological properties than using transverse relaxation time and peak area. Among the seven models, the PLSR, SVR, 1D CNN, and Transformer models effectively predicted the rheological characteristics based on LF-NMR parameters, with the highest R2 in the prediction set reaching 0.9869 and the highest RPD reaching 8.7220. This study successfully established a prediction system for the rheological behaviors and 3D printing performance of polysaccharide gels using NIR spectroscopy and LF-NMR data combined with ML methods, achieving an intelligent assessment of the 3D printing behavior of polysaccharide gels.

Low-field NMR Works as a Rapid, Automatic, Non-Invasive and Wide-Scale Coverage Technique for Aggregates Indication in Biomacromolecule Development.

Protein aggregation is challenging for biopharmaceutical drug, because it affects the stability of protein formulations in real-time. However, current techniques for protein aggregate indication meet a number of limitations including limited aggregate size range, complex pre-treatments and lack of chromatographic approaches. Herein, a rapid, automatic, non-invasive and wide-scale coverage technique for aggregates indication is developed to overcome these challenges. Firstly, the response of low-field nuclear magnetic resonance (LF-NMR) to the aggregates is explored by making a comparison with certain established techniques. LF-NMR achieves a high sensitivity of water proton transverse relaxation rate (R2 of H2O, hereinafter referred as R2(H2O)) to protein aggregates from nanometer to micrometer. Then, the quantitative relationship between R2(H2O) and aggregates is investigated furtherly. R2(H2O) could serve as an all-size coverage protein aggregates indicator during development. As a non-invasive method, LF-NMR does not need any sample handling. It takes only 44 s for one test, and saves a lot of manpower, materials and costs. Compared with other established analytical techniques, the technique developed here could be a powerful tool for a rapid, automatic, non-invasive and wide-scale coverage technique for aggregates indication in biomacromolecule development.

Effect of electrohydrodynamic (EHD) drying on active ingredients, textural properties and moisture distribution of yam (Dioscorea opposita).

This paper systematically investigates the changes in material properties during electrohydrodynamic (EHD) drying, the discharge characteristics of the EHD system as well as the active ingredients, textural properties (hardness, adhesiveness, etc.) and moisture distribution of yam under EHD, air drying and hot air drying were investigated. The results showed that the active particles and the ionized wind generated during the discharge process of the electrohydrodynamic drying device had a significant effect on the drying. Compared to thermal drying, 21 kV drying resulted in the most complete cellular structure, the best internal bound water content as well as textural properties of yam. It played a positive role in the retention of internal nutrients in yam, and the total phenol and allantoin contents were increased by 25.74% and 81.99%, respectively. These results elucidate the advantages of electrohydrodynamic drying in yam drying and provide a reference for the application of EHD in drying.

Effects of ultrasonic pretreatment on drying characteristics and water migration characteristics of freeze-dried strawberry.

The effects of ultrasonic pretreatment on the drying characteristics and microstructure of strawberry slices were investigated. The rehydration characteristics of freeze-dried products, which were pre-frozen at -20 °C and - 80 °C were explored, with a focus on water mobility and distribution. The ultrasonic pretreatment significantly increased the water mobility of the strawberry slices, resulting in a reduction in their water content. However, the application of ultrasound significantly decreased the rehydration speed, indicating a lower moisture absorption capacity in the pretreated sample. The micrographs revealed that the structure of the tissue was more uniform after ultrasonic treatment, and water loss was accelerated. In addition, the contact angle measurements showed that the samples were more hydrophobic after ultrasonic treatment, and the eutectic temperature and fold point of the samples increased. Therefore, this study found that ultrasonic-assisted freeze vacuum drying technology effectively reduces hygroscopicity, improves product storage, and represents a potential method for dried production.

Dynamic Study on Water State and Water Migration during Gluten-Starch Model Dough Development under Different Gluten Protein Contents.

Mixing is crucial for dough quality. The gluten content influences water migration in dough development and properties, leading to quality changes in dough-based products. Understanding how the gluten protein content influences water migration during dough development is necessary for dough processing. A compound flour with different gluten protein contents (GPCs, 10-26%, w/w) was used to study the dough farinograph parameters and water migration during dough development. According to the farinograph test of the gluten-starch model dough, the GPC increases the water absorption and the strength of the dough. Water migration was determined via low-field nuclear magnetic resonance (LF-NMR). With the increase in GPC, the gluten protein increases the binding ability of strongly bound water and promotes the transformation of weakly bound water. However, inappropriate GPC (10% and 26%, w/w) results in the release of free water, which is caused by damage to the gluten network according to the microstructure result. Moreover, the changes in proteins' secondary structures are related to the migration of weakly bound water. Therefore, weakly bound water plays an important role in dough development. Overall, these results provide a theoretical basis for the optimization of dough processing.

Tailoring the physicochemical properties of starch: impact of integrated ultrasonic and ethanol pretreatment on the oil uptake of infrared fried ginkgo seeds.

BACKGROUND: The structural changes of starch would have a more crucial impact on oil absorption and quality changes in starch-rich fruits and vegetables during frying process with enhanced heat transfer (such as infrared frying). In the present study, the influence of integrated ultrasonic and ethanol (US + ethanol) pretreatment on oil uptake in infrared fried (IF) ginkgo seeds was evaluated regarding modifications in the physicochemical properties of starch. The pretreatment was performed with ultrasonic (40 kHz, 300 W) and ethanol osmotic (95%, v/v) treatment individually or integrated for 40 min. RESULTS: The mass transfer in the pretreatment was facilitated by combined ultrasound and ethanol. The swelling power, solubility, and gelatinization degree of starch was significantly increased. Low-frequency-NMR curves and images revealed that the bound water fraction in ginkgo seeds was increased and the water distribution was homogenized. The results of Fourier transform-infrared spectrum and differential scanning calorimeter revealed that the crystalline regions of starch were reduced and the thermal enthalpy was decreased after US + ethanol pretreatment. The total, surface and structural oil content in IF ginkgo seeds with US + ethanol pretreatment was reduced by 29.10%, 34.52% and 29.73%, respectively. The US + ethanol pretreatment led to a thinner crust layer with increased porosity and smaller-sized pores in the IF ginkgo seeds as observed by stereo microscopy and scanning electron microscopy. CONCLUSION: The changes in structural and physicochemical properties of starch by combined ultrasound and ethanol affect the crust ratio and pore characteristics in fried high-starch fruits and vegetables, thereby reducing oil absorption. © 2024 Society of Chemical Industry.

Effects of ultrasonic power on drying kinetics and product quality of licorice extract during ultrasound-assisted vacuum drying.

BACKGROUND: Licorice extract is an important raw material for food additives and medicine. The quality of licorice extract is dictated by the drying process. The commonly used drying methods of licorice extract are not efficient in obtaining high-quality products so alternative techniques need to be developed and researched. In this study, ultrasound-assisted vacuum drying (UAVD) was first utilized to improve drying efficiency and produce a higher-quality product. The changes in water mobility of licorice extract during drying were characterized using low-field nuclear magnetic resonance. In addition, the effects of ultrasonic power on the drying dynamics, the contents of liquiritin and glycyrrhizic acid, the antioxidant capacity and the microstructure formation of licorice extract during the whole drying process were investigated. RESULTS: The drying times for licorice extract to reach equilibrium moisture content were reduced by 9.09-69.70% with UAVD at 40-200 W compared with that without ultrasonic treatment (0 W). Moreover, the proportions of bound water and semi-bound water in fresh concentrate were 3.75% and 96.25%. It was also found that high ultrasonic power promoted the flow of water and the formation of porous structure in licorice extract, which led to the improvement of drying efficiency. The contents of liquiritin (2.444%) and glycyrrhizic acid (6.514%) were retained to a large degree in the dried product at an ultrasonic power of 80 W. The DPPH inhibition rate of UAVD samples with different ultrasonic powers ranged from 84.07 ± 0.46% to 90.65 ± 0.22%. CONCLUSION: UAVD has the advantages of high efficiency and low energy consumption, which may be an alternative technology for vacuum drying widely used in industry. © 2024 Society of Chemical Industry.

Dynamic changes in the water and volatile compounds of chicken breast during the frying process.

The influence of frying times (0, 2, 4, 6, 8, and 10 min) on the continuous changes in the water distribution and the concentrations of key volatile compounds in chicken breast during the frying process were studied. The fried chicken samples could be distinguished by PCA of E-nose and PLS-DA of GC-MS. A total of 40 volatile compounds were identified by GC-MS, and 28 compounds were verified to be the key compounds after further screening by OAVs. The T22 was increased first and then decreased, while the M22 and M23 in fried chicken were considerably decreased and increased with increasing frying time, respectively. The content of the water and the total peak area of LF-NMR in fried chicken samples during the frying process significantly decreased, and the water was transferred from high to low degrees of freedom. In addition, water content, T21, T22, M22 and L* value were positively correlated with most alcohols and aldehydes, and were negatively correlated with pyrazines, while a*, b*, M23 and all amino acids were positively correlated with pyrazines and were negatively correlated with most alcohols and aldehydes. The results may guide the production processes of fried chicken and help produce high-quality chicken products.

Dynamic changes in the water distribution and key aroma compounds of roasted chicken during roasting.

The effects of roasting times (0, 2, 4, 6, 8, 10, 12, and 14 min) on the dynamic changes of the water distribution and key aroma compounds in roasted chicken during the electric roasting process were studied. In total, 36 volatile compounds were further determined by GC-MS and 11 compounds, including 1-octen-3-ol, 1-heptanol, hexanal, decanal, (E)-2-octenal, acetic acid hexyl ester, nonanal, 2-pentylfuran, heptanal, (E, E)-2,4-decadienal and octanal, were confirmed as key aroma compounds. The relaxation time of T22 and T23 was increased first and then decreased, while the M22 and M23 in roasted chicken were decreased and increased with increasing roasting time, respectively. The fluidity of the water in the chicken during the roasting process was decreased, and the water with a high degree of freedom migrated to the water with a low degree of freedom. In addition, the L*, a*, b*, M23 and all amino acids were positively correlated with all the key aroma compounds, while T22, M22 and moisture content were negatively correlated with all the key aroma compounds.

Evolution of lean meat tenderness stimulated by coordinated variation of water status, protein structure and tissue histology during cooking of braised pork.

Tenderness of lean meat in braised pork is of great importance to the consumer palatability and acceptance. The influence of water status, protein structure and histological changes on lean meat tenderness during cooking was investigated. Results indicated that lean meat began to tenderize mainly after 20 min-cooking. In the early period of cooking, the decrease of total sulfhydryl content caused the protein oxidative cross-linking, leading to the gradual unfolding of the protein structure, thus resulting in a decrease of T22 and an increase of centrifugal loss, which decreased the tenderness of lean meat. However, after cooking for 20 min, the ß-sheet decreased and random coil increased, thus generating conversion between P21 and P22. The rupture of perimysium structure was observed. Changes in protein structure, water status, and tissue histology could facilitate the initiation and development of lean meat tenderness.

Structural Characterization of Several Cement-Based Materials Containing Chemical Additives with Potential Application in Additive Manufacturing.

The rapid increase in additive manufacturing applications in all industries has highlighted the lack of innovative technologies and processes in the construction industry. Several European and international policies are in place to guide the development of the technological processes involved in the construction industry toward a sustainable future. Considering the global concerns regarding this industry, the purpose of this study was to develop new cement-based materials that are capable of accelerated hydration and early strength development for use in additive manufacturing. Ca(NO3)2·4H2O, Al2(SO4)3·18H2O and Na2S2O3·5H2O were used to obtain the accelerating effect in the hydration of Portland cement. Based on results obtained from X-ray diffraction (XRD), scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDX) techniques, as well as low-field nuclear magnetic resonance relaxometry (LF-NMR) techniques, it was demonstrated that all accelerators used have a quickening effect on cement hydration. The addition of Na2S2O3·5H2O or combined Na2S2O3·5H2O and Ca(NO3)2·4H2O led to obtaining new cement-based materials with early strength development and fast hydration of microorganized internal structures, critical characteristics for 3D printing.

Evaluation of multicomplex systems on pomegranate concentrate loaded alginate hydrogels by low-field NMR relaxometry: physicochemical characterization and controlled release study.

Alginate (ALG) and various gums are potential biomaterials to be employed in hydrogel designs for both food and biomedical applications. This study evaluated a multicomplex design by combining food grade polymers to examine their polymer-polymer interactions and design an oral delivery system for pomegranate concentrate (PC). ALG was replaced with gum tragacanth (GT), xanthan (XN) and their equal combinations (GT:XN) at 50% ratio in hydrogel fabrication. In addition to CaCI2 in binding solution, honey (H) and chitosan (CH) were also used during physical crosslinking. Relaxation time constants in NMR indicated poor ability of GT for water entrapment especially in the presence of honey (S2H). They also confirmed FTIR results indicating similar trends. Strong negative correlations were observed between T2 and texture results. GT replacement of ALG especially in the use of single CaCI2 (S2) promoted higher PC release up to 80% in digestive media compared to XN substitution (S3). This study promoted use of LF NMR as an indicator for polymer mixture characterization in complex gels. ALG based gels could be modified by replacing ALG with different kinds of gums and with use of different binding solutions to regulate target compound release in food and pharmaceutical fields. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-023-05730-2.

Effect of coagulation temperature on cooking integrity of heat and acid-induced milk gels.

Heat and acid-induced milk gels do not melt or flow upon heating and thus show great potential as a dairy-based protein source for cooking, e.g. for stews. Understanding how processing, e.g. acidification, affects the cooking behavior of these gels is therefore of great industrial interest. The cooking integrity of gels produced by rapidly acidifying milk using citric acid at temperatures of 60, 75, and 90 °C, was determined by analyzing composition, texture, and spatial water distribution before and after cooking. Increasing the acidification temperature from 60 to75 °C resulted in a significant reduction of yield, due to decreased moisture content of the gels. With increasing content of solids, the gels grew harder and denser, as observed by texture profile analysis and low-field Nuclear Magnetic Resonance. Upon cooking the 60 °C gel lost a significant amount of moisture, due to the contraction of the porous protein network. The more compact gels, prepared at 75 and 90 °C, did not lose mass indicating good cooking integrity, i.e. a gel that keeps its structure during cooking. Acidification temperature thus greatly influenced cooking integrity. The effect was mainly ascribed to the density of the gel texture, a result of the speed of protein aggregation and calcium recovery.

Characterization of Pore Size Distribution and Water Transport of UHPC Using Low-Field NMR and MIP.

Water transport is vital for the durability of ultra-high performance concrete (UHPC) in engineering, but its absorption behavior requires further comprehension. This study investigates the impact of silica fume (SF) and metakaolin (MK) on water absorption in UHPC matrix with a high volume of limestone powder (LS) under two curing temperatures, and the variation in water transport with pore size obtained by low field nuclear magnetic resonance (LF-NMR). Relations between cumulative water absorption with other properties were discussed, and the pore size distribution (PSD) measured by Mercury intrusion porosimetry (MIP) was compared with that determined by LF-NMR. Results showed that MK outperformed SF in reducing water absorption in UHPC matrix, containing 30% LS under steam curing due to the synergistic effect between MK and LS. The incorporation of LS greatly affected the water absorption process of UHPC matrix. In samples without LS, capillary and gel pores absorbed water rapidly within the first 6 h and slowly from 6 h to 48 h simultaneously. However, in samples with 30% LS, gel pore water decreased during water absorption process due to the coarsening of gel pores. MK was able to suppress gel pore deterioration caused by the addition of a large amount of LS. Compared with PSD measured by MIP, NMR performed better in detecting micropores (<10 nm).

The moisture adsorption, caking, and flowability of silkworm pupae peptide powders: The impacts of anticaking agents.

This study aimed to explore the impacts of different anticaking agents on the moisture adsorption, caking, and flowability of silkworm pupae peptide powders (SPPP). The characteristics of water distributions in SPPP with anticaking agents were investigated by LF NMR. The morphological observation of powders was analyzed by scanning electron microscope. Moisture sorption curves and moisture sorption isotherm curves indicated that calcium stearate, silicon dioxide and calcium silicate of 20 % reduced hygroscopicity and increased critical relative humidity. The angle of repose analysis revealed that anticaking agents could also increase flowability (45°-49°). LF NMR analysis indicated that anticaking agents reduced the moisture adsorption ability of SPPP. Scanning electron microscope observations demonstrated different shapes and surface morphology of SPPP using different anticaking agents. Notably, silicon dioxide served as the most effective anticaking agent by forming a physical barrier. Overall, anticaking agents can effectively delay moisture adsorption and deliquescence of SPPP by different anticaking fashions.

Hot Air Convective Drying of Ginger Slices: Drying Behaviour, Quality Characteristics, Optimisation of Parameters, and Volatile Fingerprints Analysis.

Ginger is one of the most popular spices and medical herbs with its unique pungent flavour and taste. Although there has been much research into the drying methods of ginger, the effect of drying parameters in hot air convective drying on ginger quality needs to be explored in depth. This study investigated the differences in drying behaviour and quality characteristics of ginger with the variables of temperature, thickness, and loading density. The moisture states and diffusion pattern in the different stages during the drying process were analysed using low-field NMR techniques. The results of quality evaluation showed that the temperature greatly influenced the colour and gingerol content of dried ginger, and the thickness of a ginger slice greatly influenced the rehydration rate. Optimal drying conditions were determined by considering a combination of specific energy consumptions with quality retention based on the response surface methodology: a temperature of 66.41 °C, thickness of 2 mm, and loading density of 5 kg/m2. HS-GC-IMS combined with multivariate chemometrics was used to achieve the characterisation of flavour profiles and fingerprinting of dried ginger. The principal component analysis and correlation analysis revealed that the alterations in ginger quality were intimately related to moisture diffusion during drying.

Cluster-bomb type magnetic biosensor for ultrasensitive detection of Vibrio parahaemolyticus based on low field nuclear magnetic resonance.

Herein, a novel cluster-bomb type signal sensing and amplification strategy in low field nuclear magnetic resonance was proposed, and a magnetic biosensor for ultrasensitive homogeneous immunoassay of Vibrio parahaemolyticus (VP) was developed. The capture unit MGO@Ab was magnetic graphene oxide (MGO) immobilized by VP antibody (Ab) to capture VP. And, the signal unit PS@Gd-CQDs@Ab was polystyrene (PS) pellets covered by Ab to recognize VP and Gd-CQDs i.e. carbon quantum dots (CQDs) containing lots of magnetic signal labels Gd3+. In presence of VP, the immunocomplex signal unit-VP-capture unit could be formed and separated by magnetic force conveniently from the sample matrix. With the successive introduction of disulfide threitol and hydrochloric acid, signal units were cleaved and disintegrated, resulting in a homogeneous dispersion of Gd3+. Thus, cluster-bomb type dual signal amplification was achieved through increasing the amount and the dispersity of signal labels simultaneously. Under optimal experimental conditions, VP could be detected in the concentration range of 5-1.0 × 106 CFU/mL, with a limit of quantitation (LOQ) 4 CFU/mL. In addition, satisfactory selectivity, stability and reliability could be obtained. Therefore, this cluster-bomb type signal sensing and amplification strategy is powerful in designing magnetic biosensor and detecting pathogenic bacteria.