Quantification of hexanal as an index of lipid oxidation in human milk and association with antioxidant components

MXene/Hydrogel-based bioelectronic nose for the direct evaluation of food spoilage in both liquid and gas-phase environments

Various bioelectronic noses have been recently developed for mimicking human olfactory systems. However, achieving direct monitoring of gas-phase molecules remains a challenge for the development of bioelectronic noses due to the instability of receptor and the limitations of its surrounding microenvironment. Here, we report a MXene/hydrogel-based bioelectronic nose for the sensitive detection of liquid and gaseous hexanal, a signature odorant from spoiled food. In this study, a conducting MXene/hydrogel structure was formed on a sensor via physical adsorption. Then, canine olfactory receptor 5269-embedded nanodiscs (cfOR5269NDs) which could selectively recognize hexanal molecules were embedded in the three-dimensional (3D) MXene/hydrogel structures using glutaraldehyde as a linker. Our MXene/hydrogel-based bioelectronic nose exhibited a high selectivity and sensitivity for monitoring hexanal in both liquid and gas phases. The bioelectronic noses could sensitively detect liquid and gaseous hexanal down to 10-18 M and 6.9 ppm, and they had wide detection ranges of 10-18 - 10-6 M and 6.9-32.9 ppm, respectively. Moreover, our bioelectronic nose allowed us to monitor hexanal levels in fish and milk. In this respect, our MXene/hydrogel-based bioelectronic nose could be a practical strategy for versatile applications such as food spoilage assessments in both liquid and gaseous systems.

The Effect of Holder Pasteurization and Different Variants on Breast Milk Antioxidants

BACKGROUND

After birth, breast milk (BM) is a known essential source of antioxidants for infants. We analyzed the non-enzymatic total antioxidant capacity (TAC), oxygen radical absorbance capacity (ORAC), and glutathione, calcium, transferrin, and total protein levels of human breast milk before and after Holder pasteurization (HoP).

METHODS

The collected donor BM samples were pasteurized with HoP.

RESULTS

HoP decreased TAC (-12.6%), ORAC (-12.1%), transferrin (-98.3%), and total protein (-21.4%) levels; HoP did not influence the glutathione concentration, and it increased the total calcium (+25.5%) concentration. Mothers who gave birth via Cesarean section had significantly lower TAC in their BM. TAC and glutathione levels were elevated in the BM of mothers over the age of 30. BM produced in the summer had higher glutathione and calcium levels compared to BM produced in the winter. The glutathione concentration in term milk samples was significantly higher in the first two months of lactation compared to the period between the third and sixth months. The transferrin level of BM for female infants was significantly higher than the BM for boys, and mothers with a BMI above 30 had increased transferrin in their samples.

CONCLUSIONS

Antioxidant levels in human milk are influenced by numerous factors. Environmental and maternal factors, the postpartum age at breast milk collection, and Holder pasteurization of the milk influence the antioxidant intake of the infant.

The Antioxidant Capacity of Breast Milk and Plasma of Women with or without Gestational Diabetes Mellitus

Women with gestational diabetes (GD) have reduced antioxidant capacity; however, the relationship between maternal diet, maternal biochemical capacity, breast milk concentration, and infant intake has not been adequately explored in the literature. An exploration of underlying mechanism(s) is warranted, particularly for nutrient antioxidants impacted by maternal intake. These nutrients may provide a means for modifying maternal and infant antioxidant capacity. Oxygen radical absorbance capacity (ORAC), alpha-tocopherol, ascorbic acid, and beta-carotene concentrations were measured in breast milk of women with and without GD. Plasma, three-day diet records, and breast milk were collected at 6 to 8 weeks postpartum. Student’s t-test was used to compare breast milk ORAC, nutrient antioxidant concentration and plasma ORAC between women with and without GD. Pearson correlations were used to determine associations among antioxidant concentrations in breast milk and dietary antioxidant intake. Breast milk antioxidant concentrations were associated with maternal intake of beta-carotene (r = 0.629, p = 0.005). Breast milk and plasma ORAC and antioxidant vitamin concentrations were not significantly different between GD and NG women. Breast milk ORAC associated with breast milk alpha-tocopherol for NG (r = 0.763, p = 0.010), but not GD women (r = 0.385, p = 0.35), and with breast milk ascorbic acid for GD (r = 0.722, p = 0.043) but not NG women (r = 0.141, p = 0.70; interaction p = 0.041). In GD participants, breast milk ORAC was significantly associated with plasma ORAC (r = 0.780, p = 0.039). ORAC and antioxidant vitamin concentrations in breast milk in women with GD were comparable to women with NG; however, the relationships between breast milk ORAC and vitamin concentrations differed in GD versus NG women for alpha-tocopherol and ascorbic acid.

Role of Vitamin E in Neonatal Neuroprotection: A Comprehensive Narrative Review

Vitamin E (Vit E) is an essential lipophilic antioxidant and anti-inflammatory agent that has potential as a neuroprotectant in newborn infants with brain injury. Vit E has shown promise in many in vitro studies, but success in translation to in vivo animal studies and the clinical setting has been mixed, with concern of adverse effects at high intravenous doses in preterm infants. However, a recent rise in knowledge of the beneficial effects of fat emulsions containing higher levels of Vit E, along with associated improved outcomes in some neonatal co-morbidities, has led many to reconsider Vit E administration as a potential therapeutic modality to improve neurological outcomes in the setting of neonatal brain injury. This narrative review discusses Vit E's structure, mechanism(s) of action, evidence in animal models, and association with health outcomes in neonates, including both dietary and supplemental Vit E and their bioavailability and pharmacokinetics as it relates to the brain. Lastly, long-term neurodevelopmental outcomes along with gaps in current knowledge are critiqued, which to date suggests that additional translational studies in larger animal models and assessment of safety profiles of different routes and doses of administration should be explored prior to large clinical trials. Importantly, a greater understanding of the brain region(s) and cell type(s) affected by Vit E may help to target the use of Vit E as a beneficial neuroprotective agent to specific populations or types of injury seen in newborns.

Dietary Intake of Polyphenols Enhances Executive/Attentional Functioning and Memory with an Improvement of the Milk Lipid Profile of Postpartum Women from Argentina

Puerperium may lead to memory and executive/attentional complaints that interfere with women’s daily life. This might be prevented by dietary compounds, such as neuroprotective polyphenols. Their bioactivity depends on their effects on lipid metabolism in different tissues, such as the brain, fat, and breast. Thus, a polyphenol-related cognitive improvement may be associated with changes of lipids in human milk, which are key for infant neurodevelopment. A cross-sectional study was conducted on 75 postpartum women from Córdoba (Argentina), involving several neuropsychological tests. Diet was registered to identify polyphenol intake and food pattern adherence, with sociodemographic and other psychological variables (insomnia, stress, subjective cognitive complaints) being also studied. Triacylglycerols, cholesterol, and their oxidative forms were analyzed as milk biomarkers. Multivariate statistical methods were applied. Results confirmed that women who consumed polyphenols presented better executive/attentional performance (i.e., higher correct responses, conceptual level responses, complete categories, verbal fluency; lower attentional interferences, and perseverative errors) and word retention with lower interference. Polyphenols were positively associated with milk lipids, which were higher in women with better cognition. Furthermore, they had lower oxidized triacylglycerols. In conclusion, polyphenolic intake during postpartum may improve executive/attentional functioning, memory, and milk lipid profile.

Effect of pasteurization on melatonin concentration in human breast milk

Introduction

Women who have problems with lactation can use human milk banks. Mainly this human milk is provided to premature babies and sick newborns. Human milk is the most suitable food for newborns and infants, recommended by WHO (World Health Organization). Human milk has anti-inflammatory, anti-infective, and anti-allergic properties, and also works for immunomodulation. Melatonin has a special, underestimated importance in the composition of breast milk. It is a hormone that has many body functions and, for several decades, its antioxidant potential has been increasingly talked about.

The aim of the study was to examine the effect of Holder pasteurization on melatonin concentration in human milk.

Materials and Methods

18 samples of human milk from donors from the human milk bank were used for the analysis. Melatonin concentration before and after pasteurization was determined by ELISA. In addition, the nutritional content composition of milk was analyzed using MIRIS Human Milk Analyzer and correlations examined.

Results

Melatonin concentration in human milk before pasteurization was 0.65–26.24 pg/mL (Me=9.58, IQR=12.72), while after pasteurization 0.80–29.58 pg/mL (Me=9.98, IQR=11.26). There was a positive correlation between melatonin concentration before and after pasteurization (r=0.797, p<0.001).

Conclusions

The Holder pasteurization process does not affect the concentration of melatonin in milk samples, which may be a recommendation for human milk banks.

Odor-active volatile compounds in preterm breastmilk

BACKGROUND

Volatile compounds in breastmilk (BM) likely influence flavor learning and, through the cephalic phase response, metabolism, and digestion. Little is known about the volatile compounds present in preterm BM. We investigated whether maternal or infant characteristics are associated with the profile of volatile compounds in preterm BM.

METHODS

Using solid-phase microextraction coupled with gas chromatography/mass spectrometry, we analyzed volatile compounds in 400 BM samples collected from 170 mothers of preterm infants.

RESULTS

Forty volatile compounds were detected, mostly fatty acids and their esters (FA and FAe), volatile organic compounds (VOCs), aldehydes, terpenoids, alcohols, and ketones. The relative concentration of most FA and FAe increased with advancing lactation and were lower in BM of most socially deprived mothers and those with gestational diabetes (p < 0.05), but medium-chain FAs were higher in colostrum compared to transitional BM (p < 0.001). Infant sex, gestational age, and size at birth were not associated with the profile of volatile compounds in preterm BM.

CONCLUSIONS

Sensory-active volatile FA and FAe are the major contributors to the smell of preterm BM. The associations between lactation stage, maternal characteristics, and volatile compounds, and whether differences in volatile compounds may affect feeding behavior or metabolism, requires further research.

IMPACT

Sensory-active volatile FAs are major contributors to the smell of preterm BM and are influenced by the lactation stage and maternal characteristics. Longitudinal analysis of volatile compounds in preterm BM found that FAs increased with advancing lactation. Colostrum had a higher concentration of medium-chain FAs compared to transitional BM and the concentration of these is associated with socioeconomic status, gestational diabetes, and ethnicity.

The effect of thermal pasteurization, freeze-drying, and gamma irradiation on donor human milk

The availability of donor human milk (DHM) is currently limited by the volumes that can be thermally pasteurized and kept in long-term cold storage. This study assesses the application of freeze-drying followed by low-dose gamma irradiation of DHM for simplified, safe long-term storage. Solid-phase microextraction (SPME) GC-MS, SDS and native PAGE gel electrophoresis demonstrated that the overall changes in volatile and protein profiles in Holder pasteurized and freeze-dried DHM was negligible compared to the natural variations in DHM. Freeze-dried DHM samples (moisture < 2.2 %) processed with 2 kGy gamma irradiation did not show any significant lipid oxidation end-products and variation in protein profile. Therefore, freeze-drying followed by in-packaging gamma irradiation could be a safe method for pasteurization, convenient storage and delivery of DHM at ambient temperature. These methods may generate a means to create a reserve stock of DHM for emergencies and humanitarian aid.

Olfactory Cues in Infant Feeds: Volatile Profiles of Different Milks Fed to Preterm Infants

Background: Smell is determined by odor-active volatile compounds that bind to specific olfactory receptors, allowing us to discriminate different smells. Olfactory stimulation may assist with digestion and metabolism of feeds in the neonate by activation of the cephalic phase response of digestion. Infants' physiological responses to the smell of different milks suggest they can distinguish between breastmilk and infant formula. We aimed to describe the profile of volatile compounds in preterm breastmilk and investigate how this differed from that of other preterm infant feeding options including pasteurized donor breastmilk, breastmilk with bovine milk-based fortifier, human milk-based products and various infant formulas. Methods: Forty-seven milk samples (13 different infant formulas and 34 human milk-based samples) were analyzed. Volatile compounds were extracted using Solid Phase Micro Extraction. Identification and relative quantification were carried out by Gas Chromatography with Mass Spectrometry. Principal Component Analysis (PCA) and one-way Analysis of Variance (ANOVA) with Tukey's HSD (parametric data) or Conover's post-hoc test (non-parametric data) were used as appropriate to explore differences in volatile profiles among milk types. Results: In total, 122 compounds were identified. Breastmilk containing bovine milk-based fortifier presented the highest number of compounds (109) and liquid formula the lowest (70). The profile of volatile compounds varied with 51 compounds significantly different (adjusted p < 0.001) among milk types. PCA explained 47% of variability. Compared to preterm breastmilk, the profile of volatile compounds in breastmilk with added bovine milk-based fortifier was marked by presence of fatty acids and their esters, ketones and aldehydes; infant formulas were characterized by alkyls, aldehydes and furans, and human milk-based products presented high concentrations of aromatic hydrocarbons, terpenoids and specific fatty acids. Conclusions: Sensory-active products of fatty acid oxidation are the major contributors to olfactory cues in infant feeds. Analysis of volatile compounds might be useful for monitoring quality of milk and detection of oxidation products and environmental contaminants. Further research is needed to determine whether these different volatile compounds have biological or physiological effects in nutrition of preterm infants.

Term Infants Fed Exclusively With Donor Milk May Require Vitamin C Supplementation

BACKGROUND

When there is insufficient mother's milk for preterm infants, fortified human donor milk (DM) is the preferred supplement. Recently, there is growing interest in providing DM to term infants. Aside from vitamin D, mother's milk is a complete source of nutrition for term infants. It is unknown whether supplementation of micronutrients is required for term infants exclusively fed DM, particularly for nutrients affected by heat processing, such as vitamin C. The objective of this study was to determine the total vitamin C content in DM and whether it would be adequate for an infant exclusively fed DM.

METHODS

DM samples (n = 56) were collected at a Canadian milk bank from April to August 2018. Vitamin C concentration was determined by high-performance liquid chromatography.

RESULTS

DM samples had a vitamin C concentration of 17.7 ± 9.8 mg/L (mean ± SD) and were variable, ranging from 1.9 to 43.2 mg/L. Using these values and assuming an exclusive DM consumption of 780 mL/day, the estimated vitamin C intake would be 13.8 ± 8.6 mg (mean ± SD), falling below the adequate intake of 40 mg/day for infants (0-6 months old).

CONCLUSION

Vitamin C supplementation is required for all infants if DM is the sole source of nutrition. Future studies should investigate other heat- and light-sensitive nutrients.

Characterizing the volatile compounds of different sorghum cultivars by both GC-MS and HS-GC-IMS

The current study applied both GC-MS and GC-IMS for characterizing the volatile compounds of six Australian sorghum cultivars. For raw sorghum, the result of GC-MS showed that the ester compounds were abundant in six raw samples. Among these esters, the content of hexadecanoic acid ethyl ester was highest in all of the raw samples. Compound 3-octanone only existed in Apollo, Bazley and Liberty, and 2-undecanone was found to be in MR43. The result of GC-IMS showed that the signals of benzaldehyde, 2,3-butanedione were generally noted in the six raw samples. In general, The Apollo and Buster had more volatile compounds, followed by Bazley and Liberty. In contrast, MR43 and G44 had the least volatile compounds. For cooked sorghums, more fatty aldehydes are formed compared to its corresponding raw sample, in which the current data indicated that 40 volatile compounds were identified by GC-MS, and 11 of them were identified as the key aroma compounds (OAVs > 1). More important, the variation in the compounds of hexanal, heptanal, octanal, 2-heptenal, nonanal, trans- 2-octenal, benzeneaceldehyde, (E)-2-nonenal, 1-octen-3-ol, 1-pentanol, 2-methoxy-4-vinylphenol and 2-pentylfuran might be applied for explaining the aroma characteristics among the six sorghum cultivars. The result of GC-IMS showed that 26 volatile compounds but not in the results from GC-MS detection, indicating the advantage of the methodology combination for a better understanding the impact of cultivars and cooking on volatile characteristics of the sorghums.

EFFECT OF PASTEURIZATION ON THE ANTIOXIDANT AND OXIDANT PROPERTIES OF HUMAN MILK

Objective:

To evaluate the effect of pasteurization on antioxidant and oxidant properties of human milk.

Methods:

42 samples of milk before and after pasteurisation were used to evaluate the antioxidant activity by the ferric reducing capacity and by scavenging the 2,2’-azino-bis 3-ethylbenzthiazoline-6-sulfonic acid radical. Lipid peroxidation was estimated by the concentration of malondialdehyde product using the thiobarbituric acid reactive substances assay and by the evaluation of advanced oxidation protein products.

Results:

No significant difference was observed in fresh human milk and after pasteurization in relation to antioxidant properties determined by the ferric reducing capacity (50.0±3.4% and 48.8±3.0%, respectively) and by scavenging the 2,2’-azino-bis 3-ethylbenzthiazoline-6-sulfonic acid radical (28.9±1.5% and 31.2±1.3%, respectively). The results of malondialdehyde (62.6±4.1 and 64.3±3.6 µM/mg) and protein oxidation products (59.4±3.4 and 54.2±3.8 µM/L) of fresh and pasteurized milk, respectively, did not exhibited any significant difference.

Conclusions:

This data showed that human milk has an important antioxidant activity and that the pasteurizing process does not influence the antioxidant capacity, avoiding the peroxidation of breast milk lipids and the formation of advanced protein oxidation products.

In Vitro Digestion of Grape Seed Oil Inhibits Phospholipid-Regulating Effects of Oxidized Lipids

The intake of dietary lipids is known to affect the composition of phospholipids in gastrointestinal cells, thereby influencing passive lipid absorption. However, dietary lipids rich in polyunsaturated fatty acids, such as vegetable oils, are prone to oxidation. Studies investigating the phospholipid-regulating effect of oxidized lipids are lacking. We aimed at identifying the effects of oxidized lipids from moderately (18.8 ± 0.39 meq O₂/kg oil) and highly (28.2 ± 0.39 meq O₂/kg oil) oxidized and in vitro digested cold-pressed grape seed oils on phospholipids in human gastric tumor cells (HGT-1). The oils were analyzed for their antioxidant constituents as well as their oxidized triacylglycerol profile by LC-MS/MS before and after a simulated digestion. The HGT-1 cells were treated with polar oil fractions containing epoxidized and hydroperoxidized triacylglycerols for up to six hours. Oxidized triacylglycerols from grape seed oil were shown to decrease during the in vitro digestion up to 40% in moderately and highly oxidized oil. The incubation of HGT-1 cells with oxidized lipids from non-digested oils induced the formation of cellular phospholipids consisting of unsaturated fatty acids, such as phosphocholines PC (18:1/22:6), PC (18:2/0:0), phosphoserine PS (42:8) and phosphoinositol PI (20:4/0:0), by about 40%–60%, whereas the incubation with the in vitro digested oils did not affect the phospholipid metabolism. Hence, the gastric conditions inhibited the phospholipid-regulating effect of oxidized triacylglycerols (oxTAGs), with potential implications in lipid absorption.

Determination of 2,4-decadienal in edible oils using reversed-phase liquid chromatography and its application as an alternative indicator of lipid oxidation

As a major product of linoleic acid-rich oils, 2,4-decadienal has unique reactivity that may be potentially toxic to human body. In this study, a reliable reversed-phase liquid chromatography method for the determination of carbonyls was developed, and 2,4-decadienal as the target aldehyde was validated. Furthermore, the possibility of 2,4-decadienal as a lipid oxidation marker was evaluated. The optimal sample pretreatment method was extraction by 2 mL of acetonitrile three times, followed by derivatization at 40 °C for 30 min. The method was linear, sensitive, and accurate with detection and quantification limits of 15 and 50 nmol/L, respectively, and had good average recoveries for 2,4-decadienal in oil samples. In tested edible oils, during heating at 180 °C, the level of 2,4-decadienal rose faster than other aldehydes, including one of the characteristic aldehydes, hexanal. Moreover, good linear relationships between the 2,4-decadienal content and other oxidation indices (R² = 0.858 to 0.984 for the anisidine value; R² = 0.876 to 0.986 for the total oxidation value) were observed in sunflower and corn oils under 8 hr heating at three temperatures (120, 150, and 180 °C), indicating that 2,4-decadienal can predict the oxidation of oil. PRACTICAL APPLICATION: 2,4-Decadienal is a toxic aldehyde produced by the oxidation of linoleic acid-rich oils, which is closely related to human health. This work is the first to demonstrate that 2,4-decadienal can be used as an alternative oxidation indicator for linoleic acid-rich oils and is of great significance for the quality control of edible oil in the food industry.

Long-Chain Polyunsaturated Fatty Acids and Lipid Peroxidation Products in Donor Human Milk in the United Kingdom: Results From the LIMIT 2-Centre Cross-Sectional Study

BACKGROUND

Donor human milk (DHM) is used as alternative to maternal milk to feed preterm infants; however, it may provide less long-chain (LC) polyunsaturated fatty acids (PUFAs) and more oxidized lipids, which may be detrimental to preterm infant health and development. Levels have not been reported for DHM in the United Kingdom.

METHODS

DHM (n = 19) from 2 neonatal units, preterm milk from a neonatal unit (n = 10), and term milk from the community (n = 11) were analyzed for fatty acids, malondialdehyde, 4-hydroxy-2-nonenal, and hexanal.

STUDY REGISTRATION

NCT03573531.

RESULTS

DHM had significantly lower absolute LCPUFA content than term (P < .001) and significantly lower ω-3 PUFAs than preterm milk (P < .05), although relative LCPUFA composition did not differ. Exclusive DHM feeding leads to significantly lower fat (3.7 vs 6.7 g/d) and LCPUFA (docosahexaenoic acid [DHA]: 10.6 vs 16.8 mg/d; arachidonic acid [ARA]: 17.4 vs 25.2 mg/d) intake than recommended by the European Society for Pediatric Gastroenterology, Hepatology and Nutrition, and provides 17.3% and 43.1% of the in utero accreted ARA and DHA. DHM had the highest proportion of lipid peroxidation.

CONCLUSIONS

This study confirms that DHM in the United Kingdom has insufficient LCPUFAs for preterm infants. It demonstrates for the first time that DHM has the highest level of lipid peroxidation, compared with preterm or term milk. This has important implications for preterm infant nutrition, as exclusive DHM feeding might not be suitable long term and may contribute to the development of major preterm neonatal morbidities.

The effects of storage conditions on long-chain polyunsaturated fatty acids, lipid mediators, and antioxidants in donor human milk - A review

Donor human milk (DHM) is the recommended alternative, if maternal milk is unavailable. However, current human milk banking practices may negatively affect the nutritional quality of DHM. This review summarises the effects of these practices on polyunsaturated fatty acids, lipid mediators and antioxidants of human milk. Overall, there is considerable variation in the reported effects, and further research is needed, particularly with lipid mediators and antioxidants. However, to preserve nutritional quality, DHM should be protected from light exposure and storage at 4 °C minimised, to prevent decreases in vitamin C and endocannabinoids and increases in free fatty acids and lipid peroxidation products. Storage at -20 °C prior to pasteurisation should also be minimised, to prevent free fatty increases and total fat and endocannabinoid decreases. Storage ≤-70 °C is preferable wherever possible, although post-pasteurisation storage at -20 °C for three months appears safe for free fatty acids, lipid peroxidation products, and total fat content.

Adherence to the Traditional Mediterranean Diet and Human Milk Composition: Rationale, Design, and Subject Characteristics of the MEDIDIET Study

Introduction: Knowledge about how a lactating woman's diet influences the composition of her breast milk is still very limited. In particular, no study has evaluated the role of adherence to the Mediterranean diet on human milk characteristics. Aim: We carried out an observational study to investigate the influence of mother adherence to a Mediterranean diet on her breast milk composition. Methods: Between 2012 and 2014, 300 healthy mothers, who exclusively breastfed their babies, were enrolled from five centers across Italy. During a visit to the hospital center 6 weeks after childbirth these women were asked to provide a sample of their freshly expressed breast milk and to answer a series of questions on personal characteristics and lifestyle factors. The application of a validated food frequency questionnaire allowed the collection of detailed dietary habits. Milk was collected and then stored until chemical analyses were performed. The study has been registered (Trial Registration: Dutch Trial register NTR3468). Descriptive analyses on baseline characteristics of mothers and babies were carried out on the participants, overall and stratified by center. Results: The participants had a mean age of 33 years (SD = 4.06), and a pre-pregnancy BMI of 22.3 Kg/m2 (SD = 3.22). Forty-seven percent gave birth to their first child, 40% to the second 13% to the third or subsequent child. Babies had a mean birth weight of 3,324 g (DS = 389), and a mean length of 51 cm (SD = 1.94). Fifty-three percent were males. Conclusion: The present work provides the general description and the characteristics of mothers and babies included in the MediDiet study.

Donor Human Milk: Effects of Storage and Heat Treatment on Oxidative Stress Markers

Mother's own milk is the first choice for the feeding and nutrition of preterm and term newborns. When mother's own milk is unavailable or in short supply donor human milk (DM) could represent a solution. Heat treatment and cold storage are common practices in Human Milk Banks (HMBs). Currently, Holder pasteurization process is the recommended heat treatment in all international guidelines. This method is thought to lead to a good compromise between the microbiological safety and nutritional/biological quality of DM. Moreover, storage of refrigerated milk is a common practice in HMBs and in NICUs. Depending on the length and on the type of storage, human milk may lose some important nutritional and functional properties. The available data on oxidative stress markers confirm that pasteurization and refrigeration affected this important elements to variable degrees, even though it is rather difficult to quantify the level of deterioration. Nonetheless, clinical practice demonstrates that many beneficial properties of human milk are preserved, even after cold storage and heat treatment. Future studies should be focused on the evaluation of new pasteurization techniques, in order to achieve a better compromise between biological quality and safety of DM.

Human milk enriched with human milk lyophilisate for feeding very low birth weight preterm infants: A preclinical experimental study focusing on fatty acid profile

BACKGROUND

Human milk, with essential nutrients and long chain polyunsaturated fatty acids (LC-PUFAs) such as the omega 3 and 6 fatty acids is important for development of the central nervous system and the retina in very low birth weight infants (<1,500 g). However, breast milk may not be sufficient to meet these needs. The possibility of supplementing breast milk with a lyophilisate of human milk was explored in this study. The objectives of this study were to determine the total lipid content and the lipid profile of the Human Milk on Baseline (HMB) and that of the Concentrates with the Human Milk + lyophilisate (with lyophilisate of milk in the immediate period (HMCI), at 3 months (HMC3m), and at 6 months (HMC6m) of storage).

METHODS

Fifty donors from the Human Milk Bank of Children's Hospital provided consent, and donated milk samples. Macronutrient (including total lipids) quantification was performed using the MIRIS® Human Milk Analyzer, and the fatty acid profile was determined by gas chromatography (CG-FID, SHIMADZU®).

RESULTS

There was a higher lipid concentration in HMCI relative to HMB. The concentrations of the main fatty acids (% of total) were as follows: palmitic acid (C16:0) HMB, 22.30%; HMCI, 21.46%; HMC3m, 21.54%; and HMC6m, 21.95% (p<0.01); oleic acid (C18:1n-9) HMB, 30.41%; HMCI, 30.47%; HMC3m, 30.55%; and HMC6m, 29.79% (p = 0.46); linoleic acid (C18:2n-6) HMB, 19.62%; HMCI, 19.88%; HMC3m, 19.49%; and HMC6m, 19.45% (p = 0.58); arachidonic acid (C20:4n-6) HMB, 0.35%; HMCI, 0.16%; HMC3m, 0.13%; and HMC6m, 0.15% (p<0.01); α-linolenic acid (C18:3n-3) HMB,1.32%; HMCI, 1.37%; HMC3m, 1.34%; and 1.34% HMC6m (p = 0.14); docosahexaenoic acid (C22:6n-3) HMB, 0.10%; HMCI, 0.06%; HMC3m, 0.05%; and HMC6m, 0.06% (p<0.01). There were no significant changes in the lipid profile when stored. There was no evidence of peroxidation during storage.

CONCLUSIONS

Freeze-dried human milk fortified with a human milk concentrate brings potential benefits to newborns, mainly by preserving the essential nutrients present only in breast milk; however, further clinical studies are required to evaluate the safety and efficacy of the concentrate as a standard nutritional food option for very low birth weight infants.

Redox properties of transitional milk from mothers of preterm infants

AIM

There is a discrepancy between the amount of transitional milk produced by mothers of preterm infants and the low capacity of premature infants to consume it. This milk can be used in milk banks, but previous studies found that there are large variations in the level of host-defence proteins in individual samples of milk from mothers of premature infants, which implies that large individual variations in antioxidative defence composition are also possible.

METHODS

Milk samples were collected from 20 healthy mothers of preterm infants. We determined the values for non-enzymatic antioxidative capacity parameters (oxygen radical absorbance capacity (ORAC)), static oxidation-reduction potential (ORP), activities of antioxidant defence enzymes and the amount of vitamin C in whole milk, skim and whey fractions of transitional milk.

RESULTS

The main low-molecular-weight antioxidant in transitional milk is vitamin C and most of it is contained in whey. ORAC is higher in whole transitional milk than in skim milk and whey, and ORP is lower in whole transitional milk than that in skim milk and whey. Antioxidative enzyme activities are similar in all individual samples of transitional milk from mothers of preterm infants.

CONCLUSIONS

Our results indicate that transitional milk of mothers of preterm infants shows slow individual variations in antioxidative defence composition; therefore, it can be used in human milk banks.

Effects of Pro-Oxidants and Antioxidants on the Total Antioxidant Capacity and Lipid Oxidation Products of Milk During Refrigerated Storage

Oxidized flavor is a major problem that affects the dairy industry because of its adverse effect on milk acceptability. The objectives of this research were to examine the roles of pro-oxidants and antioxidants on the oxidative stability of whole milk. In the 1st experiment, the effect of light (2300 Lux) and/or cupric sulfate (0, 0.5, and 1.0 mg/kg) as pro-oxidants in milk were investigated during an 11-d refrigerated storage period. The effects of added retinyl palmitate (1.16 mg/L; 2113 IU Vitamin A/L) and tocopheryl acetate (100 mg/kg milk fat; 5.02 IU Vitamin E/L) as antioxidants in the presence of light (2300 Lux) and light with cupric sulfate (0.05 mg/kg) during a 7-d study were investigated in the 2nd experiment. The presence of pro-oxidants significantly (P < 0.05) decreased the total antioxidant capacity (TAC) and increased the lipid oxidation products in milk during storage. Light had a greater effect in the decrease of TAC, although cupric sulfate in the presence of light significantly increased the formation of lipid oxidation products. The addition of antioxidants resulted in a significant (P < 0.05) increase in TAC on day 0. However, with exposure to light and light with cupric sulfate, the antioxidants did not result in a higher TAC in comparison to the treatments without added antioxidant. Analysis of lipid oxidation products by instrumental and sensory methods showed that the presence of light and cupric sulfate significantly (P < 0.05) increased the oxidized flavor from the control, but no significant (P > 0.05) difference in oxidized flavor intensity was detected between milk with and without added antioxidants.

PRACTICAL APPLICATION

Production and processing variables can affect the content of pro-oxidants and antioxidants in milk, which has an impact on flavor. An understanding of the role of these components in contributing to or minimizing off-flavor formation in milk, will help dairy producers to provide quality products to consumers.

Volatile Compounds Produced by Lactobacillus paracasei During Oat Fermentation

This study investigated the profiles of volatile compounds produced by Lactobacillus paracasei during oat fermentation using gas chromatography-mass spectrometry coupled with headspace solid-phase microextraction method. A total of 60 compounds, including acids, alcohols, aldehydes, esters, furan derivatives, hydrocarbons, ketones, sulfur-containing compounds, terpenes, and other compounds, were identified in fermented oat. Lipid oxidation products such as 2-pentylfuran, 1-octen-3-ol, hexanal, and nonanal were found to be the main contributors to oat samples fermented by L. paracasei with the level of 2-pentylfuran being the highest. In addition, the contents of ketones, alcohols, acids, and furan derivatives in the oat samples consistently increased with the fermentation time. On the other hand, the contents of degradation products of amino acids, such as 3-methylbutanal, benzaldehyde, acetophenone, dimethyl sulfide, and dimethyl disulfide, decreased in oat samples during fermentation. Principal component analysis (PCA) was applied to discriminate the fermented oat samples according to different fermentation times. The fermented oats were clearly differentiated on PCA plots. The initial fermentation stage was mainly affected by aldehydes, whereas the later samples of fermented oats were strongly associated with acids, alcohols, furan derivatives, and ketones. The application of PCA to data of the volatile profiles revealed that the oat samples fermented by L. paracasei could be distinguished according to fermentation time.

The Effect of Holder Pasteurization on Nutrients and Biologically-Active Components in Donor Human Milk: A Review

When a mother's milk is unavailable, the best alternative is donor milk (DM). Milk delivered to Human Milk Banks should be pasteurized in order to inactivate the microbial agents that may be present. Currently, pasteurization, performed at 62.5 °C for 30 min (Holder Pasteurization, HoP), is recommended for this purpose in international guidelines. Several studies have been performed to investigate the effects of HoP on the properties of DM. The present paper has the aim of reviewing the published papers on this topic, and to provide a comparison of the reported variations of biologically-active DM components before and after HoP. This review was performed by searching the MEDLINE, EMBASE, CINHAL and Cochrane Library databases. Studies that clearly identified the HoP parameters and compared the same DM samples, before and after pasteurization, were focused on. A total of 44 articles satisfied the above criteria, and were therefore selected. The findings from the literature report variable results. A possible explanation for this may be the heterogeneity of the test protocols that were applied. Moreover, the present review spans more than five decades, and modern pasteurizers may be able to modify the degradation kinetics for heat-sensitive substances, compared to older ones. Overall, the data indicate that HoP affects several milk components, although it is difficult to quantify the degradation degree. However, clinical practices demonstrate that many beneficial properties of DM still persist after HoP.

Antioxidative Activity of Colostrum and Human Milk: Effects of Pasteurization and Storage

OBJECTIVES

Milk banks collect, pasteurize, and freeze/store human milk. The processing may alter redox properties of milk, but the effects have not been fully examined.

METHODS

We collected 10 mature milk and 10 colostrum samples and applied a battery of biochemical assays and electron paramagnetic resonance spectroscopy to inspect changes that milk undergoes with pasteurization and 30 days storage at -20°C.

RESULTS

Pasteurization and storage of raw milk did not affect total nonenzymatic antioxidative capacity, but specific components and features were altered. Urate radical and ascorbyl radical emerge as products of exposure of milk to hydroxyl radical-generating system. Processing shifted the load of antioxidative activity from ascorbate to urate and lowered the capacity of milk to diminish hydroxyl radical. Pasteurization caused a significant drop in the activity of 2 major antioxidative enzymes-superoxide dismutase and glutathione peroxidase, whereas freezing/storage of raw milk affected only superoxide dismutase. Colostrum showed drastically higher total nonenzymatic antioxidative capacity, hydroxyl radical scavenging ability, and glutathione reductase activity compared with mature milk.

CONCLUSIONS

Pasteurization and storage affect nonenzymatic and enzymatic antioxidative agents in human milk. It appears that nonenzymatic antioxidative systems in colostrum and milk are different. The effects of processing may be partially compensated by fortification/spiking with ascorbate before use.

Volatile emission in dry seeds as a way to probe chemical reactions during initial asymptomatic deterioration

The nature and kinetics of reactions in dry seeds determines how long the seeds survive. We used gas chromatography to assay volatile organic compounds (VOCs) emitted from seeds of three unrelated species as a means to non-invasively probe chemical changes during very dry, dry, and humid storage (seeds were dried to 5.5, 33, and 75% relative humidity at room temperature). VOCs emitted from seeds stored in humid conditions reflected fermentation-type reactions, with methanol and ethanol being predominant in Lactuca sativa and Carum carvi, and acetaldehyde and acetone being predominant in Eruca vesicaria. Dried C. carvi seeds continued to emit fermentation-type products, although at slower rates than the seeds stored in humid conditions. In contrast, drying caused a switch in VOC emission in L. sativa and E. vesicaria seeds towards higher emission of pentane and hexanal, molecules considered to be byproducts from the peroxidation of polyunsaturated fatty acids. Longevity correlated best with the rate of fermentation-type reactions and appeared unrelated to the rate of lipid peroxidation. Emission of VOCs decreased when seed species were mixed together, indicating that seeds adsorbed VOCs. Adsorption of VOCs did not appear to damage seeds, as longevity was not affected in seed mixtures. Collectively, the study shows similarity among species in the types of reactions that occur in dry seeds, but high diversity in the substrates, and hence the byproducts, of the reactions. Moreover, the study suggests that the most abundant VOCs arise from degradation of storage reserves within seed cells, and that these reactions and their byproducts are not, in themselves, damaging.

Volatile profile of breast milk subjected to high-pressure processing or thermal treatment

The effect of Holder pasteurisation (HoP) (62.5°C for 30 min) or high-pressure treatments (400 or 600 MPa for 3 or 6 min) on the volatile compound profile of human breast milk was evaluated, in order to compare both preservation technologies. A total of 46 different volatile compounds was found in milk samples. The most abundant compounds detected were aliphatic hydrocarbons. In general, the effect of some high-pressure treatments on the volatile profile of human milk was less intense than that caused by HoP. The treatments at 400 and 600 MPa for 3 min maintained the volatile compounds at similar levels to those found in control milk samples. However, the application of 600 MPa for 6 min changed the original volatile compounds of human milk, even more than HoP. Since, HPP at 400 or 600 MPa for 3 min preserved the original volatile compounds of human milk, this novel process may be an alternative to thermal pasteurisation.

Effects of applying antioxidants on bond strength of bleached bovine dentin

Objectives

Some antioxidants are believed to restore dentin bond strength after dental bleaching. This study was done to evaluate the influence of antioxidants on the bond strength of bleached bovine dentin.

Materials and Methods

Thirty incisors were randomly assigned to 10 groups (two unbleached control and eight bleached groups: immediate bonding IB, 4 wk delayed bonding DB, 10% sodium ascorbate treated SA, 10% α-tocopherol treated TP groups). Teeth in half of groups were subjected to thermal stress, whereas the remaining groups were not. Resin-dentin rods with a cross-sectional area of 2.25 mm² were obtained and microtensile bond strength was determined at a crosshead speed of 1 mm/min. Fifteen specimens were prepared for SEM to compare the surface characteristics of each group. The change in dentin bond strength from thermal stress and antioxidant treatment was evaluated using two-way analysis of variance (ANOVA) and Sheffe's post hoc test at a significance level of 95%.

Results

The control group exhibited the highest bond strength values, whereas IB group showed the lowest value before and after thermocycling. The DB group recovered its bond strength similar to that of the control group. The SA and TP groups exhibited similar bond strength values with those of the control and DB groups before thermocycling. However, The TP group did not maintain bond strength with thermal stress, whereas the SA group did.

Conclusions

Applying a 10% sodium ascorbate solution rather than 10% α-tocopherol solution for 60 sec is recommended to maintain dentin bond strength when restoring non-vitally bleached teeth.

New covalent modifications of phosphatidylethanolamine by alkanals: mass spectrometry based structural characterization and biological effects

The pathophysiology of numerous human disorders, such as atherosclerosis, diabetes, obesity and Alzheimer's disease, is accompanied by increased production of reactive oxygen species (ROS). ROS can oxidatively damage nearly all biomolecules, including lipids, proteins and nucleic acids. In particular, (poly)unsaturated fatty acids within the phospholipid (PL) structure are easily oxidized by ROS to lipid peroxidation products (LPP) carrying reactive carbonyl groups. Carbonylated LPP are characterized by high in vivo toxicity due to their reactivity with nucleophilic substrates (Lys-, Cys-and His-residues in proteins or amino groups of phosphatidylethanolamines [PE]). Adducts of unsaturated LPP with PE amino groups have been reported before, whereas less is known about the reactivity of saturated alkanals - which are significantly increased in vivo under oxidative stress conditions - towards nucleophilic groups of PLs. Here, we present a study of new alkanal-dipalmitoyl-phosphatidylethanolamine (DPPE) adducts by MS-based approaches, using consecutive fragmentation (MS(n)) and multiple reaction monitoring techniques. At least eight different DPPE-hexanal adducts were identified, including Schiff base and amide adducts, six of which have not been reported before. The structures of these new compounds were determined by their fragmentation patterns using MS(n) experiments. The new PE-hexanal adducts contained dimeric and trimeric hexanal conjugates, including cyclic adducts. A new pyridine ring containing adduct of DPPE and hexanal was purified by HPLC, and its biological effects were investigated. Incubation of peripheral blood mononuclear cells and monocytes with modified DPPE did not result in increased production of TNF-α as one selected inflammation marker. However, incorporation of modified DPPE into 1,2-dipalmitoleoyl-sn-phosphatidylethanolamine multilamellar vesicles resulted in a negative shift of the transition temperature, indicating a possible role of alkanal-derived modifications in changes of membrane structure.

Plasma malondialdehyde levels in children on 12-hour cyclic parenteral nutrition: are there health risks?

In children undergoing total parenteral nutrition (PN), lipids provide a key source of calories preventing or correcting energy deficits and improving outcomes. However, some of these lipids may undergo oxidation leading to the formation of malondialdehyde (MDA), a cytotoxic byproduct found in these patients. This paper aims to describe a sensitive method for detecting MDA and discuss its role in certain diseases commonly found in children on regular PN. To quantify MDA levels in children benefitting from long-term cyclic PN, a reliable and sensitive high-performance liquid chromatographic method based on a 1-step derivatization/extraction procedure analysis with ultraviolet determination at 305 nm wavelength was achieved. In control children without PN, MDA levels were on average 3.30 ± 0.08 µM. However, in children nourished intravenously by fat emulsion for a long time, in which liver problems have been identified, the circulating concentrations of MDA ranged widely at both the start and the end of a session, 3- to 10-fold, respectively, in comparison with the levels measured in controls. This finding indicates that PN administrated long term raises plasma MDA levels, indicating chronic exposure and therefore a possible health risk, particularly liver damage. This preliminary study using a limited number of patients and controls showed that children undergoing long-term PN are strongly exposed to MDA, which must be considered as a potent toxic compound rather than a simple marker of lipid peroxidation.

Modulation of NF-κB and Nrf2 control of inflammatory responses in FHs 74 Int cell line is tocopherol isoform-specific

The present study investigates the relative ability of α-, γ-, and δ-tocopherol (Toc) to modulate cell signaling events that are associated with inflammatory responses in fetal-derived intestinal (FHs 74 Int) cells. Secretion of the proinflammatory cytokine IL-8 in FHs 74 Int cells was stimulated in the following order: α-Toc<γ-Toc<δ-Toc. A similar proinflammatory response was observed when inflammation was induced in FHs 74 Int cells. Modulation of IL-8 expression by Toc corresponded to an isoform-specific modulation of NF-κB and nuclear factor-erythroid 2-related factor 2 (Nrf2) cell signaling pathways involved in expression of proinflammatory cytokines and antioxidant enzymes, respectively. δ-Toc and, to a lesser extent, γ-Toc activated NF-κB and Nrf2 signaling, as indicated by the greater nuclear translocation of transcription factors. Activation of NF-κB signaling by γ- and δ-Toc was accompanied by upregulation of NF-κB target genes, such as IL-8 and prostaglandin-endoperoxide synthase 2, with and without a prior IFNγ-PMA challenge. Nevertheless, γ- and δ-Toc, particularly δ-Toc, concurrently downregulated glutamate-cysteine ligase, a Nrf2 target gene that encodes for glutathione biosynthesis. This observation was substantiated by confirmation that γ- and δ-Toc were effective at decreasing glutamate-cysteine ligase protein expression and cellular glutathione content. Downregulation of glutathione content in fetal intestinal cells corresponded to induction of apoptosis-mediated cytotoxicity. In conclusion, γ- and δ-Toc are biologically active isoforms of vitamin E and show superior bioactivity to α-Toc in modulating cell signaling events that contribute to a proinflammatory response in fetal-derived intestinal cells.