Effects of Different Prebiotics on the Gel Properties of Milk Protein and the Structural Features of Yogurt.

The impact of prebiotics on the structural characteristics of yogurt is an important aspect of evaluating its functional properties. This study aimed to evaluate and compare the effects of several commonly used prebiotics, including fructooligosaccharide (FOS), galactooligosaccharide (GOS), inulin (INU), polydextrose (PDX), and xylooligosaccharide (XOS), on the gel properties of milk protein and the structural features, with respect to the texture and rheology, of stirred yogurt during and after fermentation. The results revealed that the supplementation of INU, PDX, and XOS was involved in the construction of protein networks during fermentation, promoting a viscous and more elastic gel structure, due to the enhanced protein-water interactions. This resulted in a significant increase (p < 0.05) in structural stability (higher critical strain (γc) and greater thixotropy), firmness, cohesiveness, and rheology (G' and G″) and a significant decrease (p < 0.05) in the loss of yogurt during centrifugation. Conversely, the supplementation of GOS and FOS did not appear to be involved in the construction of the protein network and barely affected the rheological properties of the gel during fermentation. However, a significant increase (p < 0.05) in viscosity and firmness, and a slight decrease (p > 0.05) in loss during centrifugation were still observed in the yogurt. These findings could be useful for a comprehensive assessment of the application potential of these prebiotics in yogurt, when combined with their respective prebiotic properties.

Variation of Aroma Components of Pasteurized Yogurt with Different Process Combination before and after Aging by DHS/GC-O-MS.

Pasteurized yogurt is a healthy yogurt that can be stored in ambient temperature conditions. Dynamic headspace sampling (DHS) combined with gas chromatography-olfactory mass spectrometry (GC-O-MS), sensory evaluation, electronic nose (E-nose), and partial least squares discriminant analysis (PLS-DA) were used to analyze the flavor changes of pasteurized yogurt with different process combinations before and after aging. The results of odor profiles showed that the sensory descriptors of fermented, sweet, and sour were greatly affected by different process combinations. The results of odor-active compounds and relative odor activity value (r-OAV) showed that the combination of the production process affected the overall odor profile of pasteurized yogurt, which was consistent with the sensory evaluation results. A total of 15 odor-active compounds of 38 volatile compounds were detected in pasteurized yogurt samples. r-OAV results revealed that hexanal, (E)-2-octenal, 2-heptanone, and butanoic acid may be important odor-active compounds responsible for off-odor in aged, pasteurized yogurt samples. PLS-DA and variable importance of projection (VIP) results showed that butanoic acid, hexanal, acetoin, decanoic acid, 1-pentanol, 1-nonanal, and hexanoic acid were differential compounds that distinguish pasteurized yogurt before and after aging.

Lung ultrasound to diagnose infectious pneumonia of newborns: A prospective multicenter study.

INTRODUCTION: Whether lung ultrasound (LUS) can be used for pathogenic diagnosis remains controversial. This study was conducted to clarify whether ultrasound has diagnostic value for etiology. METHODS: A total of 135 neonatal pneumonia patients with an identified pathogen were enrolled from the newborn intensive care units of 10 tertiary hospitals in China. The study ran from November 2020 to December 2021. The infants were divided into various groups according to pathogens, time of infection, gestational age, and disease severity. The distribution of pleural line abnormalities, B-line signs, and pulmonary consolidation, as well as the incidence of air bronchogram and pleural effusion based on LUS, were compared between these groups. RESULTS: There were significant differences in pulmonary consolidation. The sensitivity and specificity of the diagnosis of severe pneumonia based on the extent of pulmonary consolidation were 83.3% and 85.2%, respectively. The area under the receiver operating characteristic curve for the identification of mild or severe pneumonia based on the distribution of pulmonary consolidation was 0.776. CONCLUSION: LUS has good performance in diagnosing and differentiating the severity of neonatal pneumonia but cannot be used for pathogenic identification in the early stages of pneumonia.

Characterization of Key Odor-Active Off-Flavor Compounds in Aged Pasteurized Yogurt by Sensory-Directed Flavor Analysis.

The purpose of this study was to determine the key odor-active compounds contributing to the off-flavor of aged pasteurized yogurt (APY) using sensory-directed flavor analysis. Additionally, different extraction methods were compared to determine their effects on the volatile compounds, including dynamic headspace sampling (DHS), solid-phase microextraction, and stir bar sorptive extraction, and DHS was found to be suitable for this study. The results showed that comprehensive two-dimensional gas chromatography-olfactometry-mass spectrometry analysis (GC × GC-O-MS) had more advantages in separating and identifying the volatile compounds than the traditional GC-O-MS. A total of 17 odor-active compounds were determined in the fresh pasteurized yogurt and APY samples by DHS coupled with GC × GC-O-MS. The dynamic headspace dilution analysis demonstrated that 2-heptanone and hexanal were the most vital components in APY with the highest flavor dilution factor. Furthermore, the spiking and omission experimental results revealed that the odor-active compounds, such as 2-heptanone, butanoic acid, pentanoic acid, hexanal, and (E)-2-heptenal, were the key odor-active off-flavor contributors in APY. Therefore, these compounds could be used as potential indicators to determine the freshness of pasteurized yogurt.

Lung Ultrasound to Diagnose Pneumonia in Neonates with Fungal Infection.

With the improvement in survival rates of low-birthweight and very premature infants, neonatal fungal infection, especially fungal pneumonia, is becoming more and more common, but the diagnosis is always challenging. Recently, lung ultrasound (LUS) has been used to diagnose pneumonia in newborn infants, but not fungal pneumonia. This paper summarizes the ultrasonographic features of seven cases of neonatal fungal pneumonia, such as lung consolidation with air bronchograms, shred signs, lung pulse, pleural line abnormalities, and different kinds of B-lines. It was confirmed that LUS plays an important role in the diagnosis of fungal pneumonia in newborn infants.

Accuracy and Reliability of Lung Ultrasound to Diagnose Transient Tachypnoea of the Newborn: Evidence from a Meta-analysis and Systematic Review.

OBJECTIVE: Transient tachypnoea of the newborn (TTN) is one of the most common causes of neonatal respiratory distress (RD) during the newborn period. Chest radiography (CXR) is commonly used to rule out the diagnosis, but TTN is often misdiagnosed as neonatal respiratory distress syndrome (NRDS) on the basis of CXR alone. Increasing evidence suggests that lung ultrasound (LUS) may be a reliable diagnostic tool for transient tachypnoea of the newborn. However, studies of the diagnostic efficiency of LUS are still lacking. This study was aimed to evaluate the accuracy and reliability of LUS for diagnosing TTN by conducting a systematic review and meta-analysis. STUDY DESIGN: We searched for articles in the Embase, PubMed, and Cochrane Library databases from inception until May 31, 2020. The selected studies were diagnostic accuracy studies that reported the utility of LUS in the diagnosis of TTN. Two researchers independently extracted data and assessed quality using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. Then, we created a bivariate model of mixed effects to calculate the sensitivity and specificity of LUS in diagnosing TTN. A summary receiver operator characteristic (SROC) curve was constructed to summarize the performance characteristics of LUS. RESULTS: Six studies involving 617 newborns were included in the review. LUS had a pooled sensitivity of 0.98 (confidence interval [CI]: 0.92-1.00) and a specificity of 0.99 (CI: 0.91-1.00). The area under the curve for LUS was 1.00 (0.98-1.0). Meta-regression revealed that LUS had a significant diagnostic accuracy for TTN. CONCLUSION: The performance of ultrasound for the detection of TTN was excellent. Considering the various advantages of LUS compared with chest radiographs in diagnosing TTN, this study supports the routine use of LUS for the detection of TTN. KEY POINTS: · Lung ultrasound is a highly accurate diagnostic tool, which may be a viable and superior alternative to CXR, in diagnosing TTN.. · Lung ultrasound can help differentiate TTN from other etiologies of respiratory distress in neonates.. · There are still some controversies on the ultrasound diagnostic criteria of TTN..

Specification and guideline for technical aspects and scanning parameter settings of neonatal lung ultrasound examination.

Lung ultrasound (LUS) is now widely used in the diagnosis and monitor of neonatal lung diseases. Nevertheless, in the published literatures, the LUS images may display a significant variation in technical execution, while scanning parameters may influence diagnostic accuracy. The inter- and intra-observer reliabilities of ultrasound exam have been extensively studied in general and in LUS. As expected, the reliability declines in the hands of novices when they perform the point-of-care ultrasound (POC US). Consequently, having appropriate guidelines regarding to technical aspects of neonatal LUS exam is very important especially because diagnosis is mainly based on interpretation of artifacts produced by the pleural line and the lungs. The present work aimed to create an instrument operation specification and parameter setting guidelines for neonatal LUS. Technical aspects and scanning parameter settings that allow for standardization in obtaining LUS images include (1) select a high-end equipment with high-frequency linear array transducer (12-14 MHz). (2) Choose preset suitable for lung examination or small organs. (3) Keep the probe perpendicular to the ribs or parallel to the intercostal space. (4) Set the scanning depth at 4-5 cm. (5) Set 1-2 focal zones and adjust them close to the pleural line. (6) Use fundamental frequency with speckle reduction 2-3 or similar techniques. (7) Turn off spatial compounding imaging. (8) Adjust the time-gain compensation to get uniform image from the near-to far-field.

Diagnostic value of lung ultrasound for neonatal respiratory distress syndrome: a meta-analysis and systematic review.

AIM: Neonatal respiratory distress syndrome (NRDS) is one of the most common and severe diseases in neonatal intensive care units worldwide. Increasing evidence suggests that lung ultrasound (LUS) may be a reliable diagnostic tool for neonatal respiratory distress syndrome. The aim of study was to evaluate the diagnostic accuracy of LUS for NRDS with a systematic review and meta-analysis. MATERIAL AND METHODS: We searched for articles in EMBASE, PubMed and Cochrane Central from inception until 17 August 2019. The selected studies were diagnostic accuracy studies that reported the utility of LUS in the diagnosis of NRDS. Two researchers independently extracted data and assessed quality using the QUADAS-2 tool. Then, we created a bivariate mixed effects model to calculate the sensitivity and specificity of LUS in diagnosing NRDS. A summary receiver operator characteristic (SROC) curve was constructed to summarize the performance characteristics of LUS. RESULTS: Nine studies involving 703 infants were included in the review. LUS had a pooled sensitivity of 0.99 (CI: 0.92-1.00) and a specificity of 0.95 (CI: 0.87-0.98). The areas under the curve for LUS was 0.99 (0.98-1.0). Meta-regression revealed that LUS had a significant diagnostic accuracy for NRDS. CONCLUSION: LUS is a promising method that is easily carried out, inexpensive, nonionizing and repeatable and can be performed at the bedside. Current evidence supports LUS as a useful imaging alternative for the diagnosis of NRDS.

Mechanisms of neuroprotection from hypoxia-ischemia (HI) brain injury by up-regulation of cytoglobin (CYGB) in a neonatal rat model.

This study was designed to investigate the expression profile of CYGB, its potential neuroprotective function, and underlying molecular mechanisms using a model of neonatal hypoxia-ischemia (HI) brain injury. Cygb mRNA and protein expression were evaluated within the first 36 h after the HI model was induced using RT-PCR and Western blotting. Cygb mRNA expression was increased at 18 h in a time-dependent manner, and its level of protein expression increased progressively in 24 h. To verify the neuroprotective effect of CYGB, a gene transfection technique was employed. Cygb cDNA and shRNA delivery adenovirus systems were established (Cygb-cDNA-ADV and Cygb-shRNA-ADV, respectively) and injected into the brains of 3-day-old rats 4 days before they were induced with HI treatment. Rats from different groups were euthanized 24 h post-HI, and brain samples were harvested. 2,3,5-Triphenyltetrazolium chloride, TUNEL, and Nissl staining indicated that an up-regulation of CYGB resulted in reduced acute brain injury. The superoxide dismutase level was found to be dependent on expression of CYGB. The Morris water maze test in 28-day-old rats demonstrated that CYGB expression was associated with improvement of long term cognitive impairment. Studies also demonstrated that CYGB can up-regulate mRNA and protein levels of VEGF and increase both the density and diameter of the microvessels but inhibits activation of caspase-2 and -3. Thus, this is the first in vivo study focusing on the neuroprotective role of CYGB. The reduction of neonatal HI injury by CYGB may be due in part to antioxidant and antiapoptotic mechanisms and by promoting angiogenesis.

Transglutaminase catalyzed cross-linking of sodium caseinate improves oxidative stability of flaxseed oil emulsion.

Sodium caseinate was modified by transglutaminase catalyzed cross-linking reaction prior to the emulsification process in order to study the effect of cross-linking on the oxidative stability of protein stabilized emulsions. The extent of the cross-linking catalyzed by different dosages of transglutaminase was investigated by following the ammonia production during the reaction and using SDS-PAGE gel. O/W emulsions prepared with the cross-linked and non-cross-linked sodium caseinates were stored for 30 days under the same conditions. Peroxide value measurement, oxygen consumption measurement, and headspace gas chromatography analysis were used to study the oxidative stability of the emulsions. The emulsion made of the cross-linked sodium caseinate showed an improved oxidative stability with reduced formation of fatty acid hydroperoxides and volatiles and a longer period of low rate oxygen consumption. The improving effect of transglutaminase catalyzed cross-linking could be most likely attributed to the enhanced physical stability of the interfacial protein layer against competitive adsorption by oil oxidation products.

Charge modifications to improve the emulsifying properties of whey protein isolate.

Whey protein isolate was modified by ethylene diamine in order to shift its isoelectric point to an alkaline pH. The extent of the modification was studied using SDS-PAGE and MALDI-TOF mass spectrometry. The modified whey proteins were used as an emulsifier to stabilize oil-in-water emulsions at acidic and neutral pH ranges, and their emulsifying properties were compared with that of the unmodified whey proteins and with the previously studied ethylene diamine modified sodium caseinate. The emulsifying activity of the modified whey proteins was similar to that of the unmodified ones, but the stability of an emulsion at pH 5 was significantly improved after the modification. Charge and coverage of droplet surface and the displacement of the interfacial proteins by surfactant Tween 20 were further studied as a function of pH. As compared with the unmodified whey proteins, the modified ones were proven to cover the interface more efficiently with extensive surface charge at pH 5, although the interfacial layer was less resistant to the surfactant displacement.

Improving laccase catalyzed cross-linking of whey protein isolate and their application as emulsifiers.

Whey protein isolate (WPI) was chemically modified by vanillic acid in order to enhance its cross-linkability by laccase enzyme. Incorporation of methoxyphenol groups created reactive sites for laccase on the surface of the protein and improved the efficiency of cross-linking. The vanillic acid modified WPI (Van-WPI) was characterized using MALDI-TOF mass spectrometry, and the laccase-catalyzed cross-linking of Van-WPI was studied. Furthermore, the vanillic acid modification was compared with the conventional approach to improve laccase-catalyzed cross-linking by adding free phenolic compounds. A small extent of the vanillic acid modification significantly improved the cross-linkability of the protein and made it possible to avoid color formation in a system that is free of small phenolic compounds. Moreover, the potential application of Van-WPI as emulsifier and the effect of cross-linking on the stability of Van-WPI emulsion were investigated. The post-emulsification cross-linking by laccase was proven to enhance the storage stability of Van-WPI emulsion.

Crosslinking food proteins for improved functionality.

Different possibilities for protein crosslinking are examined in this review, with special emphasis on enzymatic crosslinking and its impact on food structure. Among potential enzymes for protein crosslinking are transglutaminase (TG) and various oxidative enzymes. Crosslinking enzymes can be applied in cereal, dairy, meat, and fish processing to improve the texture of the product. Most of the current commercial applications are based on TG. The reaction mechanisms of the crosslinking enzymes differ, which in turn results in different technological properties.

Sodium caseinates with an altered isoelectric point as emulsifiers in oil/water systems.

Sodium caseinate was chemically modified in order to alter its isoelectric point (pI). Negatively charged carboxylic groups were introduced to lower the pI, and positively charged amino groups to achieve the opposite. Different chemical amino acid modification approaches were studied and the modified proteins were characterized using free amino group assays, SDS-PAGE, MALDI-TOF mass spectrometry, and zeta potential measurements. Oil-in-water emulsions were prepared using these modified caseinates. The pH stability behavior of the emulsions was monitored, and interestingly, the stability of the emulsion could be modulated through steering the pI of caseinate. Using different modified caseinates, it was possible to create emulsions that were stable in the acid, neutral, and alkaline regions of the pH spectrum. The stability behavior of the emulsions correlated well with the theoretical and experimentally determined pI values of the caseinates. Storage stability of emulsions was also studied at pH values around 7, and emulsions made of modified caseinates showed storage stability similar to that of unmodified caseinate emulsions.