Untargeted metabolomics provide new insights into the implication of Lactobacillus helveticus strains isolated from natural whey starter in methylglyoxal-mediated browning.

Hard cheeses may occasionally show a brown discolouration during ripening due to multifactorial phenomena that involve bacteria and give rise to pyrazines arising from methylglyoxal. The present work aimed at developing a novel approach to investigate the role of natural starters in browning. To this object, 11 strains of L. helveticus were incubated in a medium containing 10 % rennet casein dissolved in whey, and then growth was monitored by measuring pH and number of genomes/mL. Browning was assessed through CIELab analysis, methylglyoxal production was determined by targeted mass spectrometry, and untargeted metabolomics was used to extrapolate marker compounds associated with browning discoloration. The medium allowed the growth of all the strains tested and differences in colour were observed, especially for strain A7 (ΔE* value 15.92 ± 0.27). Noteworthy, this strain was also the higher producer of methylglyoxal (2.44 µg/mL). Metabolomics highlighted pyrazines and ß-carboline compounds as markers of browning at 42 °C and 16 °C, respectively. Moreover, multivariate statistics pointed out differences in free amino acids and oligopeptides linked to proteolysis, while 1,2-propanediol and S-Lactoylglutathione suggested specific detoxification route in methylglyoxal-producing strains. Our model allowed detecting differences in browning amid strains, paving the way towards the study of individual L. helveticus strains to identify the variables leading to discoloration or to study the interaction between different strains in natural whey starters.

Adverse Childbirth and Perinatal Outcomes Among Healthy, Low-Risk Pregnant Women with Abnormal Total Gestational Weight Gain.

Purpose: Little is known on the potential effects of abnormal gestational weight gain (GWG) among low-risk, healthy pregnant women with no comorbidities or gestational complications. We investigated perinatal outcomes of these pregnancies according to GWG as per the 2009 National Academy of Medicine (NAM) recommendations. Materials and Methods: A retrospective analysis of prospectively collected data of low-risk pregnant women giving birth at term between January 2016 and December 2020. Inclusion criteria were normal pregestational body mass index (pBMI) (18.5-24.9 kg/m2) and no pregestational or gestational complication. Self-reported prepregnancy weight was used to calculate pBMI; GWG was the difference between maternal weight at childbirth and prepregnancy weight. Women were classified according to the 2009 NAM guidelines for GWG: insufficient (iGWG, <11.5 kg), adequate (aGWG, 11.5-16 kg), and excessive (eGWG, >16 kg). Logistic regression analysis with aGWG as referent was performed to independently estimate dose-response associations. Results: During the study period, there were 4,127 (33.1%) births fulfilling the inclusion criteria. Fifty-two percent of women gained outside the recommended range: 33.5% had iGWG and 18.7% had eGWG. iGWG women were 40% more likely to have early-term births and small for gestational age neonates. In turn, eGWG women displayed increased odds of prolonged pregnancy (adjusted odds ratio [aOR] 1.32), cesarean section in labor (aOR 1.50), high-degree perineal tears (aOR 2.04), postpartum hemorrhage ≥1,000 mL (aOR 1.54), and large for gestational age newborns (aOR 1.83). Conclusion: Our data show that abnormal GWG independently associates with heightened risk of adverse outcomes among healthy, low-risk pregnant women with normal pBMI and no comorbidity or gestational complication.