Effect of different salts on the foaming properties of model protein systems for infant formula.

This multiscale study aimed to evaluate the effects of different salts (NaCl, KCl, MgCl2, and CaCl2) on the foaming capacity (FC) and foam stability (FS) of model protein systems (MPS) for infant formula via changes in surface and structural properties. Our results showed that the FC and FS of MPS were increased with the addition of NaCl, KCl, and MgCl2, whereas CaCl2 significantly decreased FC (79.5 ± 10.6%) and increased FS (93.2 ± 2.2%). The surface hydrophobicity was increased and the net charge and surface tension were reduced after the addition of salts. Structural analysis revealed the reduction of intensity of intrinsic fluorescence spectroscopy and UV absorption, and the conversion of α-helix into ß-strand, which was attributed to protein agglomeration. Additionally, MgCl2 and CaCl2 exhibited larger size and lower net charge compared with NaCl and KCl, indicating a greater ability to bind to charged amino acids and form larger aggregates. Correlation analysis indicated that FC was positively related to adsorbed protein and ß-turn and negatively correlated with particle size. In addition, FS showed a positive correlation with ß-strand, apparent viscosity, and zeta potential. However, it exhibited a negative correlation with ß-turn, α-helix, and sulfhydryl content. These results provide a theoretical reference for further understanding of the effect of salts on the foaming properties of MPS.

Effects of Transglutaminase Concentration and Drying Method on Encapsulation of Lactobacillus plantarum in Gelatin-Based Hydrogel.

Lactobacillus plantarum is a kind of probiotic that benefits the host by regulating the gut microbiota, but it is easily damaged when passing through the gastrointestinal tract, hindering its ability to reach the destination and reducing its utilization value. Encapsulation is a promising strategy for solving this problem. In this study, transglutaminase (TGase)-crosslinked gelatin (GE)/sodium hexametaphosphate (SHMP) hydrogels were used to encapsulate L. plantarum. The effects of TGase concentration and drying method on the physiochemical properties of the hydrogels were determined. The results showed that at a TGase concentration of 9 U/gGE, the hardness, chewiness, energy storage modulus, and apparent viscosity of the hydrogel encapsulation system were maximized. This concentration produced more high-energy isopeptide bonds, strengthening the interactions between molecules, forming a more stable three-dimensional network structure. The survival rate under the simulated gastrointestinal conditions and storage stability of L. plantarum were improved at this concentration. The thermal stability of the encapsulation system dried via microwave vacuum freeze drying (MFD) was slightly higher than that when dried via freeze drying (FD). The gel structure was more stable, and the activity of L. plantarum decreased more slowly during the storage period when dried using MFD. This research provides a theoretical basis for the development of encapsulation technology of probiotics.

Effects of polymerized goat milk whey protein on physicochemical properties and microstructure of recombined goat milk yogurt.

Goat milk whey protein concentrates were manufactured by microfiltration (MF) and ultrafiltration (UF). When MF retentate blended with cream, which could be used as a starting material in yogurt making. The objective of this study was to prepare goat milk whey protein concentrates by membrane separation technology and to investigate the effects of polymerized goat milk whey protein (PGWP) on the physicochemical properties and microstructure of recombined goat milk yogurt. A 3-stage MF study was conducted to separate whey protein from casein in skim milk with 0.1-µm ceramic membrane. The MF permeate was ultrafiltered using a 10 kDa cut-off membrane to 10-fold, followed by 3 step diafiltration. The ultrafiltration-diafiltration-treated whey was electrodialyzed to remove 85% of salt, and to obtain goat milk whey protein concentrates with 80.99% protein content (wt/wt, dry basis). Recombined goat milk yogurt was prepared by mixing cream and MF retentate, and PGWP was used as main thickening agent. Compared with the recombined goat milk yogurt without PGWP, the yogurt with 0.50% PGWP had desirable viscosity and low level of syneresis. There was no significant difference in chemical composition and pH between the recombined goat milk yogurt with PGWP and control (without PGWP). Viscosity of all the yogurt samples decreased during the study. There was a slight but not significant decrease in pH during storage. Bifidobacterium and Lactobacillus acidophilus in yogurt samples remained above 106 cfu/g during 8-wk storage. Scanning electron microscopy of the recombined goat milk yogurt with PGWP displayed a compact protein network. Results indicated that PGWP prepared directly from raw milk may be a novel protein-based thickening agent for authentic goat milk yogurt making.

Co-fermented cow milk protein by Lactobacillus helveticus KLDS 1.8701 and Lactobacillus plantarum KLDS 1.0386 attenuates its allergic immune response in Balb/c mice.

Milk protein is one of the major food allergens. As an effective processing method, fermentation may reduce the potential allergenicity of allergens. This study aimed to evaluate the therapeutic potential of co-fermented milk protein using Lactobacillus helveticus KLDS 1.8701 and Lactobacillus plantarum KLDS 1.0386 in cow milk protein allergy (CMPA) management. This study determined the secondary and tertiary structures of the fermented versus unfermented proteins by Fourier-transform infrared spectroscopy and surface hydrophobicity to evaluate its conformational changes. Our results showed that different fermentation methods have significantly altered the conformational structures of the cow milk protein, especially the tertiary structure. Further, the potential allergenicity of the fermented cow milk protein was assessed in Balb/c mice, and mice treated with the unfermented milk and phosphate-buffered saline were used as a control. We observed a significant reduction in allergenicity via the results of the spleen index, serum total IgE, specific IgE, histamine, and mouse mast cell protease 1 in the mice treated with the co-fermented milk protein. In addition, we analyzed the cytokines and transcription factors expression levels of spleen and jejunum and confirmed that co-fermentation could effectively reduce the sensitization of cow milk protein by regulating the imbalance of T helper (Th1/Th2 and Treg/Th17). This study suggested that changes of conformational structure could reduce the potential sensitization of cow milk protein; thus, fermentation may be a promising strategy for developing a method of hypoallergenic dairy products.

Infant formula supplemented with 1,3-olein-2-palmitin regulated the immunity, gut microbiota, and metabolites of mice colonized by feces from healthy infants.

Infant formula is currently an important food to cope with insufficient breastfeeding. Although 1,3-olein-2-palmitin (OPO) has been used in infant formula, its effects on the immune system, gut microbiota, and metabolites for infants remain unclear. This study constructed a mouse model of colonizing healthy infant feces using antibiotic treatment and fecal microbial transplantation. Thus, the gap between the infant formula supplemented with OPO and human milk in mouse serum biochemistry, immune system, intestinal microbiota, short-chain fatty acid production, and metabolites was evaluated. Our results showed that regarding IL-9, IL-10 levels, fecal secretory IgA, and endotoxin, formula supplemented with OPO and human milk types had comparable levels. Additionally, OPO slightly increased the content of short-chain fatty acids. The 16S rRNA gene sequence analysis and metabonomics analysis demonstrated that feeding different foods affects the gut microbiota of mice; in particular, supplementing formula feeding with OPO enriched the abundance of bifidobacteria. Furthermore, feeding different foods leads to unique intestinal content of metabolites, and the gut microbiota regulates the metabolites' differences. Our results reveal a brand new perspective of OPO regarding gut microbiota and metabolites.

The prevalence and characterization of Bacillus cereus isolated from raw and pasteurized buffalo milk in southwestern China.

Bacillus cereus is an important food-borne pathogenic bacteria and a putrid microorganism in the dairy industry. Raw and pasteurized buffalo milk play important roles in the dairy market in southwestern China. However, the reports on the prevalence and characterization of B. cereus strains isolated from the above sources are lacking. In this study, 150 raw buffalo milk samples and 300 pasteurized buffalo milk samples were collected from 3 provinces in southwestern China. The genotype, virulence gene distribution, antibiotic resistance, and biofilm-forming ability of isolates were analyzed. Ninety-six B. cereus strains were isolated and identified: 50 isolates (33.3%) from buffalo raw milk and 46 isolates (15.3%) from pasteurized buffalo milk. These strains were classified into 41 sequence types (ST) and 5 groups, of which ST857 was the predominant ST. The detection rates of virulence genes nheABC cluster, hblACD cluster, cytK, bceT, entFM, hlyII, and cesB were 89.6%, 13.5%, 64.6%, 71.9%, 84.4%, 62.5%, and 6.25%, respectively. The antimicrobial susceptibility testing showed that more than 90% of the isolates were susceptible to gentamicin, chloramphenicol, ciprofloxacin, erythromycin, vancomycin, and tetracycline, as well as resistant to ampicillin, cefepime, oxacillin, and rifampin. The results of biomass biofilm evaluation of the isolates on the stainless-steel tube showed that the optical density values at a wavelength of 595 nm of all strains in group I were greater than 1, with the strongest overall biofilm-forming ability among 5 groups, and the overall biofilm-forming ability of group III was the weakest. There was a relationship between the biofilm-forming ability and phylogenetic relationship of B. cereus strains. Taken together, our findings are the first to report the contamination situation and characterization of B. cereus isolated from raw and pasteurized buffalo milk in southwestern China as well as indicate the potential risk posed by this pathogen to dairy industry and public health.

Proteolytic activities of combined fermentation with Lactobacillus helveticus KLDS 1.8701 and Lactobacillus plantarum KLDS 1.0386 reduce antigenic response to cow milk proteins.

Cow milk protein is one of the leading food allergens. This study aimed to develop an effective method for reducing milk sensitization by evaluating antigenicity of fermented skim milk protein using Lactobacillus helveticus KLDS 1.8701, Lactobacillus plantarum KLDS 1.0386, and a combination of both strains. The proteolytic systems of strains in terms of genotype and phenotype are characterized by complete genome sequence, and evaluation the antigenicity of skim milk proteins was determined by ELISA and liquid chromatography with tandem mass spectrometry. Our results showed that the genomes encoded a variety of peptidase genes. For fermented skim milk, the degree of hydrolysis of the combined strains was higher than that of individual strain. Electrophoresis showed that the band color density of α-casein (α-CN) by fermentation of the combined strains was reduced when compared with control group. The fermentation process of the combined strains inhibited α-CN, ß-lactoglobulin, and α-lactalbumin antigenicity by 69.13, 36.10, and 20.92, respectively. Major allergic epitopes of α-CN and ß-lactoglobulin were cleaved by abundant proteases of combined strains. In all, this study showed that the fermentation process involving both L. helveticus and L. plantarum strains could reduce cow milk protein allergenicity through the combination of cell-envelope proteinase and peptidase on α-CN.

Genotyping, Antimicrobial Susceptibility and Biofilm Formation of Bacillus cereus Isolated from Powdered Food Products in China.

This study was conducted to reveal the genotyping, antimicrobial susceptibility, and biofilm formation of Bacillus cereus isolated from powdered food products in China. Five hundred powdered food samples were collected from five provinces in China: 100 samples each of powdered infant formula (PIF), soy milk powder (SMP), lotus root powder (LRP), walnut powder (WP), and rice flour (RF). The genotyping of isolates was analyzed using multilocus sequence typing; meanwhile, antimicrobial susceptibility, and ability of biofilms formation on stainless steel tube of isolates were evaluated. Forty-two B. cereus strains were detected with an overall contamination rate of 8.4%, as well as, the highest B. cereus contamination rate was found in SMP (10%), followed by LRP (9%), WP (9%), RF (8%), and PIF (6%). These isolates were divided into 22 sequence types (STs); among them, ST32 (4/42, 9.5%) was the predominant ST. Phylogenetic relationships showed that the 42 strains of B. cereus were divided into three groups (group I, group II, and group III). Antimicrobial susceptibility testing indicated that all isolates were susceptible to tetracycline, gentamicin, erythromycin, and chloramphenicol, while resistant to ampicillin, cefepime, oxacillin, and rifampin. The analysis of ability of biofilm formation on stainless steel tube showed optical density (OD)595 value of 66.7% of B. cereus isolates was greater than 1. The OD595 level of isolates belonging to group III was higher compared with the other two groups, and OD595 values of B. cereus HB1 and HN5 were greater than 2. These findings improved the understanding of the characteristics of B. cereus isolated from powdered food products in China, and provided a theoretical basis for the prevention and control of B. cereus in food industry.

Longitudinal Changes in Crude Protein and Amino Acids in Human Milk in Chinese Population: A Systematic Review.

OBJECTIVE: More than 20% of the world population live in China, which has made significant achievement in human milk research. Part of the data that were published in Chinese were, however, unavailable to non-Chinese speakers. There was also no comprehensive overview of crude protein and amino acid levels in human milk in Chinese population. This systematic review aimed to compile the data on human milk crude protein and amino acid levels in Chinese population. METHODS: After searching for and screening original research articles in both English and Chinese, 23 published from 1987 to 2019 were identified (18 in Chinese and 5 in English). The data were pooled into 9 defined lactation stages. RESULTS: Crude protein and amino acids (protein bound plus nonprotein bound) concentrations gradually decreased during the first 60 postpartum days and remained relatively static thereafter. The concentrations and dynamic change of crude protein and amino acids were similar to those in other populations. By contrast, the longitudinal changes in free amino acids (nonprotein bound) were less clear due to the limited data available. Several common weaknesses were identified in these studies. CONCLUSIONS: Our study represented the most comprehensive overview on crude protein and amino acid concentrations in human milk in Chinese population, and enhanced the knowledge of protein and amino acid intakes and requirements by Chinese infants.

pH-induced physiochemical and structural changes of milk proteins mixtures and its effect on foaming behavior.

Milk proteins are well known to produce aerated food due to the amphiphilicity. However, milk proteins are commonly added in blends for the desirable properties in food industry. In this study, the foaming properties of milk protein mixtures (MPM), a mixtures of whey protein isolated (WPI) and milk protein concentrate (MPC), was studied through foaming capacity (FC), foam stability (FS), and foam morphology at pH 3.0-9.0. Physiochemical, structural, surface properties, and Pearson correlation analysis were measured to gain insight into foaming behavior. Results indicated that MPM showed excellent FC (113.0-114.3 %) and FS (90.7-93.0 %) at pH 6.0-9.0, and foam displayed a smaller size and uniform distribution. MPM solutions showed smaller particles, higher solubility, and lower apparent viscosity at pH 6.0-9.0, which resulted in an increase in surface pressure and adsorption rate (Kdiff), facilitating more protein absorbed to interface. To further investigate structural changes, various spectral methods were used, in which the structure of MPM was changed with pH. Correlation analysis further suggests that Kdiff and solubility positively affect the formation of foam, while free sulfhydryl and ß-sheet contributed to stabilizing foams. These findings provide valuable information on MPM as ingredients for aerated foods under acidic, neutral, and alkaline conditions.

A combination of phospholipids and long chain polyunsaturated fatty acids supports neurodevelopmental outcomes in infants: a randomized, double-blind, controlled clinical trial.

Phospholipids (PLs) and long-chain polyunsaturated fatty acids (LCPUFAs) are naturally present in breast milk and play important roles in promoting the growth of the infant. Several studies have investigated the effects of the combination of PLs and LCPUFAs on neurodevelopment. However, data on the effectiveness of infant formula containing both PLs and LCPUFAs on the neurodevelopment of infants is still scarce. This randomized, double-blind, controlled clinical study was designed to evaluate the effect of an infant formula enriched with PLs and LCPUFAs on growth parameters and neurodevelopmental outcomes in term infants up to 365 days of age. Infants were enrolled within 30 days of birth who were then randomly assigned to either a control group (n = 150) or an investigational group (n = 150). Both groups consist of cow's milk-based formula which were generally identical in terms of composition, except that the investigational formula was additionally supplemented with PLs and LCPUFAs. The infants were followed for the first year of life. Breastfed infants were the reference (n = 150). Bayley Scales of Infant Development [3rd edition (Bayley-III)], Carey Toddler Temperament Scales (TTS), MacArthur-Bates Communicative Development Inventories (CDI), Single Object Attention and Free Play Tasks were used to evaluate neurodevelopmental outcomes of infant at 365 days of age. In addition, Ages and Stages Questionnaires (ASQ) were also conducted at 120, 180, and 275 days of age. Compared to breastfeeding, both infant formulas were well-tolerated and provided adequate growth, with no adverse events being reported throughout the study. Infants of the investigational group showed higher mean scores in Bayley-III cognitive performance (104.3 vs. 99.0, p < 0.05), language (106.9 vs. 104.5, p < 0.05), and motor skills (109.2 vs. 103.9, p < 0.05) compared the control group. Similar results were being reported for other developmental scales including TTS and ASQ. Notably, the test scores of infants fed the investigational formula were similar to those who were breastfed. Our results indicate that PL and LCPUFA supplementation may be beneficial for neurodevelopment of infants throughout the first year of life. Further studies are needed to investigation long-term effects PL and LCPUFA on neurodevelopment in early life.

An investigation of association between human milk mineral patterns and infant growth.

Introduction: Human milk is widely acknowledged as the optimal food for infant aged 0 ~ 6 months. While there has been extensive documentation on the mineral and trace element composition of human milk, results on the relationship between mineral content and infant growth remain mixed. This cross-sectional study aims to explore human milk mineral patterns and to investigate associations between human milk mineral patterns, human milk metabolomic profile and infant growth. Methods: A total of 200 breast milk samples from seven cities in China was included. Human milk mineral and trace elements was detected by inductively coupled plasma mass spectrometer (ICP-MS). K-means cluster analysis was utilized to derived human milk mineral patterns. Untargeted human milk metabolomic profiles was determined using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Differences of infant growth rate and metabolomic profiles were then compared across patterns identified. Results: Three human milk mineral patterns were identified. Cluster I was characterized as the highest levels of potassium, magnesium and calcium, while the lowest levels of copper, zinc, manganese and selenium. Cluster II showed the most abundant sodium, iron, zinc, manganese and selenium. Cluster III had the lowest levels of sodium, potassium, magnesium, iron and calcium. Infants of cluster I showed significantly higher length-for-age z score (0.60 ± 2.03, p = 0.03). Compared with other clusters, samples of cluster I showed lower expression of metabolites of arachidonic acid (ARA) and nicotinate and nicotinamide metabolism pathway. Discussion: A human milk mineral pattern was identified which is related to increased infant growth rate and altered metabolic signature. Future work is needed to understand these human milk patterns in terms of biologic mechanisms and generalization to other populations.

Longitudinal Changes in Human Milk Minerals and Vitamins in the Chinese Population: A Scoping Review.

This scoping review aims to investigate longitudinal changes in minerals and vitamins concentrations in human milk among the Chinese population. Following the PRISMA-ScR guidelines, a comprehensive and systematic literature search was conducted using both English and Chinese databases. Data were extracted and categorized into six defined lactation stages. We found that the concentration of most minerals decreased throughout the lactation period, although calcium (Ca) and magnesium (Mg) fluctuated slightly across lactation periods. Fat-soluble vitamins also showed a decline throughout the lactation period, while water-soluble vitamins exhibited an increasing trend. However, folic acid, biotin, and pantothenic acid demonstrated a downward trend. Overall, this review has identified the longitudinal changes in minerals and vitamins concentrations in human milk among the Chinese population. In order to conduct a more in-depth examination of maternal characteristics and nutritional factors of the composition of human milk, it is recommended to utilize standardized protocols for the collection and analysis of human milk samples.

Enhancing immune regulation in vitro: the synergistic impact of 3'-sialyllactose and osteopontin in a nutrient blend following influenza virus infection.

Natural components of breast milk, human milk oligosaccharides (HMOs) and osteopontin (OPN) have been shown to have a variety of functional activities and are widely used in infant formulas. However, the preventive and therapeutic effects of both on influenza viruses are not known. In this study, antiviral assays using a human laryngeal carcinoma cell line (HEP-2) showed that 3'-sialyllactose (3'-SL) and OPN had the best antiviral ability with IC50 values of 33.46 µM and 1.65 µM, respectively. 3'-SL (10 µM) and OPN (4 µM) were used in combination to achieve 75% inhibition. Further studies found that the combination of 200 µg/mL of 3'-SL with 500 µg/mL of OPN exerted the best antiviral ability. The reason for this was related to reduced levels of the cytokines TNF-α, IL-6, and iNOS in relation to mRNA expression. Plaque assay and TCID50 assay found the same results and verified synergistic effects. Our research indicates that a combination of 3'-SL and OPN can effectively reduce inflammatory storms and exhibit anti-influenza virus effects through synergistic action.

Characteristics of casein phosphopeptides in Chinese human milk and its correlation with infant growth: A cross-sectional study.

This research aimed to investigate the characteristics of casein phosphopeptides in Chinese human milk, and their potential relationship to infant growth. Using the liquid chromatography-Orbitrap-mass spectrometry technique, a total of 15 casein phosphopeptides were identified from 200 human milk samples. Also, our results indicate that casein phosphopeptides were phosphorylated with only one phosphate. The relative concentrations of casein phosphopeptides at 6 months postpartum were increased compared with milk at 2 months (FDR < 0.05). Significantly positive correlations were observed between casein phosphopeptides and infant growth, as shown by four casein phosphopeptides were positively correlated with the infants' weight-for-age Z-scores (rs range from 0.20 to 0.29), and three casein phosphopeptides were positively correlated with the infants' length-for-age Z-scores (rs range from 0.19 to 0.27). This study is the first to reveal the phosphorylated level and composition of casein phosphopeptides in Chinese human milk, and their potential relationship with infant growth.

Elucidating gut microbiota and metabolite patterns shaped by goat milk-based infant formula feeding in mice colonized by healthy infant feces.

The gut microbiota plays an evolutionarily conserved role in host metabolism, which is influenced by diet. Here, we investigated differences in shaping the gut microbiota and regulating metabolism in cow milk-based infant formula, goat milk-based infant formula, and mix milk-based infant formula compared with pasteurized human milk. 16S rRNA results showed that goat milk-based infant formula selectively increased the relative abundance of Blautia, Roseburia, Alistites and Muribaculum in the gut compared to other infant formulas. Metabolomics identification indicated that goat milk-based infant formula mainly emphasized bile acid biosynthesis, arachidonic acid metabolism and steroid biosynthesis metabolic pathways. Metabolites associated with these metabolic pathways were positively associated with increased microorganisms in goat milk-based infant formula, particularly Alistipes. Furthermore, we found a deficiency of Akkermansia abundance in three infant formula-fed compared to pasteurizedhuman milk-fed. This study presents new insights into the improvement and application of goat milk-based infant formulas in terms of intestinal microecology.

Supplementing maternal diet with milk oligosaccharides and probiotics helps develop the immune system and intestinal flora of offsprings.

Intestinal flora is very important for improving the development of the immune system in newborns. Maternal diet during pregnancy and lactation is one of the key factors affecting the growth and development of offspring. The objective of the present study was to examine whether supplementation of maternal diet with milk oligosaccharides and Bifidobacterium could influence the development of the intestinal flora and immune system of neonatal mice. In total, 30 pregnant Institute of Cancer Research (ICR) mice were randomly divided into six groups: a control group (basal diet) and five intervention groups (basal diet supplemented with different doses of 2'-fucosyllactose [2'-FL] and Bifidobacterium Bb12) during the pregnancy period. All female mice were monitored for physical health during gavage. After delivery, the number of mice in each litter, any deformity, and the development of the offspring were recorded. The spleen, blood, and fecal samples of six groups of 10-12 day-old offspring were collected. The results demonstrated that maternal milk oligosaccharides and probiotics conferred protective effects against lipopolysaccharide (LPS)-induced immunosuppression in mice offspring by significantly enhancing the immune organ indexes, splenocyte proliferation, immunoglobulin (immunoglobulin G, A, M) production as well as improving the macrophage phagocytosis (p < .05). The abundance of Lactobacilli and Bifidobacteria in the feces of offspring mice in the intervention groups was significantly higher than that of the offspring mice in the control group (p < .05). These findings suggest that the combination of 2'-FL and Bifidobacterium Bb12 displayed synergistic interactions between the two components that could promote the development of the immune system of the offsprings and improve their microbiota through maternal ingestion.

Determination of oxylipins and their precursors in breast milk by solid phase extraction-ultra high performance liquid chromatography-triple quadrupole tandem mass spectrometry.

Oxylipins and their precursors (long-chain polyunsaturated fatty acids, LCPUFAs) are key intercellular signaling molecules influencing the inflammatory response. Each oxylipin has pro- and/or anti-inflammatory effects, and the relative abundance of different oxylipins can alter the inflammatory balance, making it important to clarify the oxylipin profile of breast milk for optimal infant health. The extraction, identification, and simultaneous quantification of oxylipins in breast milk are challenging due to the structural similarity, limited stability, and the low endogenous concentration of oxylipins and the complex matrix of breast milk. This study aimed to develop a solid phase extraction-ultra high performance liquid chromatography-triple quadrupole tandem mass spectrometry (SPE-UPLC-MS/MS) method for the comprehensive and specific quantification of oxylipins and their precursors in breast milk. The LC conditions (including column, mobile phase, and gradient conditions) and SPE procedure (including SPE cartridges, elution solvent, and elution volume) were optimized to achieve accurate quantification and better analyte recovery. A single 18-minute chromatographic run allows for the quantification of 20 oxylipins and 5 PUFAs. The results showed good linearity (R2 > 0.99) over the concentration range of 2 to 100 ng/mL, with the instrument detection limits ranging from 0.01 to 0.90 ng/mL for oxylipins and 0.02 to 0.59 ng/mL for PUFAs. The method is rapid, sensitive, and reproducible (RSD ≤ 10%) and is suitable for the quantitative analysis of oxylipins and their precursors in infant formula samples.

Antibiofilm effects of punicalagin against Staphylococcus aureus in vitro.

Staphylococcus aureus is a common foodborne pathogen which can form biofilms to help them resist to antimicrobials. It brings great harm to human health. Punicalagin has good antimicrobial activities against S. aureus, but its effect on biofilm formation has not been clearly illustrated. The aim of this study was to explore the antibiofilm effects of punicalagin against S. aureus. Results showed that punicalagin did not significantly interfere with the growth of S. aureus at the concentrations of 1/64 MIC to 1/16 MIC. The biomass and metabolic activity of biofilms were significantly reduced when exposed to sub-inhibitory concentrations of punicalagin. The number of viable cells in the biofilms was also decreased after punicalagin treatment. Scanning electron microscopy and confocal laser scanning microscopy images confirmed that punicalagin damaged the structure of biofilms. The antibiofilm mechanism was partly due to the modification of the cell surface which led to the reduction of cell surface hydrophobicity. These findings suggest that punicalagin has the potential to be developed as an alternative to control S. aureus biofilms.

Characterization of the odor compounds in human milk by DHS/GC × GC-O-MS: A feasible and efficient method.

Odor analysis of human milk (HM) is often challenging. Here, a new strategy for the analysis of odorants in HM using dynamic headspace sampling combined with comprehensive two-dimensional gas chromatography-olfactometry-mass spectrometry (DHS/GC × GC-O-MS) was established based on the comparison of different extraction methods and instrument modes. Overall, DHS/GC × GC-O-MS was proved to be able to provide higher extraction efficiency and better analytical results of the odor-active compounds (OACs) in HM, meanwhile, the salt addition during the extraction further promoted the release of the odorants. Twenty key OACs in HM were identified by flavor dilution analysis and odor activity calculation, of which 1-octen-3-one, 2,3-butanedione, (E)-2-nonenal, and nonanal contributed significantly to the odor of HM. In addition, 2,3-pentanedione was detected as a key OAC in HM for the first time. This study provided a powerful analytical strategy for the comprehensive odor analysis of HM.