Effects of Sterilization, Packaging, and Storage on Vitamin C Degradation, Protein Denaturation, and Glycation in Fortified Milks

Precise Photothermal Treatment of Methicillin-Resistant S. aureus Infection via Phage Lysin-Cell Binding Domain-Modified Gold Nanosheets

The increasing spread of antibiotic resistance in bacterial pathogens poses a huge threat to global human health. Precise targeting of bacterial pathogens while avoiding collateral damage to healthy tissues has become the overriding goal for bacterial infection treatment. Inspired by the host specificity of bacteriophages, a biomimetic intelligent platform was designed for highly precise photothermal treatment herein. As proof-of-concept, the lysin cell-binding domain (CBD) from a newly discovered virulent methicillin-resistant S. aureus (MRSA) phage Z was applied to the functionalization of gold nanosheets. Our results demonstrated that the bionanocomposite gold particles (Au@PEG-CBDz) could be effectively delivered directly to MRSA and kill them effectively under near infrared irradiation in vitro, while displaying good in vivo biocompatibility. This work is the first to report the combination of phage lysin navigatory function with photothermal effect-induced bactericidal activity from Au nanosheets, providing a novel therapeutic mode for the precision treatment of antibiotic-resistant bacterial infections.

Fortification of cocoa semi-skimmed milk formulations with native lactic acid bacteria: Cell viability, physicochemical and functional properties for developing novel foods

This study aimed to evaluate several cocoa semi-skimmed milk formulations (CSMFs) as potential carriers of native lactic acid bacteria (LAB) strains to obtain novel probiotic beverages (PBs) with improved technological and functional characteristics, and satisfactorily organoleptic acceptance. The viability of two native LAB (Lactiplantibacillus plantarum UTNGt2 and Lactiplantibacillus pentosus UTNGt5) was assessed in comparison with two references (Lactococcus lactis subsp. lactis ATCC11474 and Limosilactobacillus reuteri DSM17938) strains in supplemented CSMFs throughout storage with refrigeration. The optimum conditions to produce novel beverages supplemented with native LAB were pH 6.6, 42°C, and 1 h of fermentation. Moreover, the effect of LAB strains fortification on pH, titratable acidity, total solids (°Brix), total polyphenolic compounds (TPC), antioxidant capacity (AOX), and ascorbic acid content (AAC), total proteins and fat, at initial and final storage was evaluated. The addition of two native LAB strains did alter the physicochemical quality of CSMFs to a lesser extent, where the bioactive molecules improved significantly (p < 0.05) with the increase of cocoa concentration and depending on the supplied strain. Although a statistically significant (p < 0.05) decrease in cell counts was recorded during storage, the LAB cells were found to be viable up to 21 days of storage at 4°C (>6 logCFU/ml), which is sufficient in number to prove their stability in vitro. Overall organoleptic results suggested that LAB supplementation had a significant impact on sensory attributes with satisfactory acceptability (>78%) of PBs containing the native strains and 1-2% cocoa, while CSMFs counterparts were less appreciated (40%) as perceived off-flavor. It appears that supplying bacteria to CSMF preserves flavor in the final product. Furthermore, the final beverages were free of harmful bacteria; thus, they comply with consumer safety regulations. This study concludes that CSMF can be used as a carrier of native LAB strains, maintaining cell viability, unaltered physicochemical properties, and improved functional and sensory characteristics, for which final beverages can be regarded as functional food. From the application standpoint, these formulations are an alternative to delivering native LAB strains and could help the cocoa and dairy industry to develop more attractive products for the growing regional market.

Dietary advanced glycation end-products, 2-monochloropropane-1,3-diol esters and 3-monochloropropane-1,2-diol esters and glycidyl esters in infant formulas: Occurrence, formulation and processing effects, mitigation strategies

Infant formula contains thermal processing contaminants, such as dietary advanced glycation end-products (dAGEs), glycidyl esters (GEs), 2-monochloropropane-1,3-diol esters and 3-monochloropropane-1,2-diol esters (MCPDEs). This systematic review aimed to gain insights into the occurrence of these contaminants in different types of infant formula, to understand potential effects of the formulation and processing of infant formulas on these contaminants, as well as into possible mitigation strategies. The occurrence of dAGEs in infant formula depends on the recipes and processing conditions. Hydrolyzed protein formulations promote dAGEs formation in infant formula since peptides are more prone to glycation than intact proteins, which is reflected in high dAGEs concentration in hypoallergenic infant formula. Different carbohydrates in recipes result into different glycation extents of infant formula: maltodextrin containing formulas contained less dAGEs than those with lactose. Concerning mitigation strategies, applying ultra-high-temperature (UHT) treatment during milk processing leads to less dAGEs formation than using in-bottle sterilization. Although data are limited, evidence showed that encapsulation of raw ingredients or the use of antioxidants or enzymes in recipes is promising. The occurrence of MCPDEs and GEs in infant formula fully depends on the vegetable oils used in the recipe. High levels of these contaminants can be found when relatively high amounts of palm oils or fats are used. The mitigation of MCPDEs and GEs should therefore be performed on fats and oils before their application to infant formula recipes. Data and knowledge gaps identified in this review can be useful to guide future studies.

Spectroscopic techniques for monitoring changes in the quality of milk and other dairy products during processing and storage

The application of spectroscopic techniques can help in alleviating problems encountered during the processing of milk and dairy products. Indeed, traditional analytical methods (e.g., physicochemical measurements, sensory, chromatography) are relatively expensive, time-consuming, and require chemicals and sophisticated analytical equipment, and skilled operators. Hence, there is a need to develop faster and less costly methods for accurately monitoring changes in the quality of milk and other dairy products during processing and storage.Many nondestructive and noninvasive instrumental techniques are available for inline and online monitoring of food. These include fluorescence spectroscopy, mid-infrared (MIR), near-infrared (NIR), nuclear magnetic resonance (NMR), etc. These techniques are usually used in combination with chemometric tools a to explore the information present in spectral data.This review article will discuss the potential of the above-mentioned spectroscopic techniques for monitoring chemical modifications of dairy products and the prediction of their functional properties during processing. The advantages and disadvantages of each technique are also discussed in this review. Finally, some conclusions are drawn, and the future trends of these methods are presented.

Proteomic and immunochemical approaches to understanding the glycation behaviour of the casein and β-lactoglobulin fractions of flavoured drinks under UHT processing conditions

Dairy technology used to produce sweetened milk products might introduce additional advanced glycation end products (AGEs) into the diet. These molecular messengers are linked to detrimental health effects. Using a model accurate to the thermal treatment, reducing sugars, main protein content, and prolonged storage of ultra-high-temperature-sterilized (UHT) milk, we studied the behaviour of milk proteins during glycation. Two-dimensional electrophoresis (2-DE) profiles and western blots of glycated total casein revealed the major contributions of αs2-casein and β-casein and the relatively minor contributions of κ-casein towards the formation of Nε-carboxymethyllysine (CML)-positive aggregates. Glycated κ-casein had the lowest furosine (FUR), 5-hydroxymethylfurfural (HMF) and AGEs content. Conversely, the α-casein fraction demonstrated a high susceptibility to glycation, having the highest FUR, HMF and AGE levels. The gel-filtration elution profiles and the corresponding fraction fluorescence revealed that glycated casein aggregates were highly fluorescent, while the β-lactoglobulin glycation profile was similar to that of bovine serum albumin, and fluorescence was detected mainly in tetramers. Although CML is not a cross-linking AGE, it was only detected in large molecular aggregates and not in glycated monomers. Our results also indicate that in casein, glycation-induced changes in the UHT conditions were less deleterious than the subsequent 90 day storage period.

Quality changes of long-life foods during three-month storage at different temperatures

The aim of this study was to describe quality changes of eight long-life foods (instant potato purée with milk, instant goulash soup, canned white-type cheese, pre-baked baguette, szeged goulash meal-ready-to-eat, canned chicken meat, pork pate and canned tuna fish) during three-month storage at 4 different temperatures (-18 °C, 5 °C, 23 °C and 40 °C). These temperatures were chosen to simulate various climatic conditions in which these foods could be used to ensure the boarding during crisis situations and military operations to provide high level of sustainability. Foods were assessed in terms of microbiological (total number of aerobic and/or facultative anaerobic mesophilic microorganisms, number of aerobic and anaerobic spore-forming microorganisms, number of enterobacteria, number of yeasts and/or moulds), chemical (pH-values, dry matter, fat, crude protein, ammonia and thiobarbituric acid reactive substances contents), texture profile (hardness) and sensory (appearance, consistency, firmness, flavour and off-flavour) analyses. Microbiological analyses showed expected results with the exception of szeged goulash, pork pate and tuna fish, which, although being sterilised products, contained some counts of bacteria. The decrease of pH-values and increase of dry matter, ammonia and thiobarbituric acid reactive substances contents were observed during the storage of all foods due to prolonged storage time and/or elevated storage temperature. Furthermore, according to texture profile analysis, hardness of cheese and baguette rose as a result of both storage temperature and time. Finally, the highest storage temperature (40 °C) resulted in a deterioration of sensory quality (especially flavour) of most foods; the exceptions were pate and tuna fish which retained good sensory quality throughout 3-month storage at all temperatures.

Response surface methodology (RSM) in evaluation of the vitamin C concentrations in microwave treated milk

During the microwave treatment process of the milk, response surface methodology (RSM) based on three-level three-factorial Box-Behnken design was used. The response vitamin C concentration was studied. The predicted value of model (11.84 μg/mL) was in excellent accordance with experimental value (11.83 μg/mL). Milk layer thickness was the most significant factor that affects the measured responses, and the effects of microwave time and microwave power were dependent on milk layer thickness levels. The variables microwave time,milk layer thickness and microwave power have the opposite effect on vitamin C concentration in milk treated by microwave. Synergistic interactions between milk layer thickness and microwave power was highly significant (p < 0.0001).

The effect of long-term storage on the quality of sterilized processed cheese

The aim of this work is to evaluate the effect three different storage temperatures (6, 23 and 40 °C) on the sterilized processed cheese quality during 24-month storage. Sterilized processed cheese (SPC) is a product with extended shelf life (up to 2 years). The samples of SPC were subjected to basic chemical analyses, i.e. pH-values, dry matter, fat, crude protein and ammonia content, and microbiological analyses, i.e. total number of microorganisms, number of coliforms, colony forming units of yeasts and/or moulds and spore-forming microorganisms. Furthermore, amino acid content (ion-exchange chromatography), protein profile (SDS-PAGE) and fat globules size (image analysis of microscopic technique) were monitored and sensory analysis (scale test and pair comparative test) was implemented, too. Increasing storage temperature and length evoked decrease of total amino acid content and protein nutrition value, increase of ammonia amount, protein changes, enlargement of fat globule size and deterioration of sensory properties of SPC. All the changes grew expressive with increasing storage temperature and time.

Decreasing retinol and α-tocopherol concentrations in human milk and infant formula using varied bottle systems

Expressing human milk has become a more common alternative for mothers, as the average work demand has increased. As more mothers must work, bottle feeding trends are increasingly common. The handling and storage of human milk introduce the risk of degradation to expressed human milk and infant formula. In following a 20-minute simulated feeding, Vitamin C has been found to degrade. Vitamin C acts as an anti-oxidant and is responsible for shielding other nutrients from oxidation, such as retinol and alpha-tocopherol. By analyzing a 20-minute simulated feeding, retinol and alpha-tocopherol each displayed decreases over time significantly different than that of the Control, which was milk not exposed to bottle feeding. In human milk, retinol showed as high as a 9.5% decrease compared to the Control. Similar trends were seen with the infant formula samples. The correlation between degradation and bottle feeding systems was dependent upon the formation of bubbles in the milk as the milk was removed from the bottle. The analysis indicated a decrease of up to 12%, as seen in retinol, and 35%, as seen in alpha-tocopherol. These decreases in retinol and alpha-tocopherol should be considered when using a bottle feeding system to deliver either human milk or formula to an infant. More research is necessary to determine the effect of this decrease on the nutritional status of infants, particularly premature infants, who are at higher risk for nutrient deficiencies.

A diet based on high-heat-treated foods promotes risk factors for diabetes mellitus and cardiovascular diseases

BACKGROUND

The modern Western lifestyle is characterized by the consumption of high-heat-treated foods because of their characteristic taste and flavor. However, it has been shown that treating food at high temperatures can generate potentially harmful compounds that promote inflammation and cardiovascular disease in subjects with diabetes.

OBJECTIVE

The aim of this study was to determine whether high-heat-treated foods also pose a risk for healthy subjects.

DESIGN

A randomized, crossover, diet-controlled intervention trial with 62 volunteers was designed to compare the potential metabolic effects of 2 diets, one that was based on mild steam cooking and another that was based on high-temperature cooking. These 2 diets differed mainly in their contents of Maillard reaction products (MRPs). MRPs were assessed in the diet and in subjects' feces, blood, and urine samples, with N(epsilon)-carboxymethyllysine as an indicator of MRPs. Biological indicators of glucose and lipid metabolism as well as oxidative stress were analyzed in subjects after 1 mo on each diet.

RESULTS

In comparison with the steamed diet, 1 mo of consuming the high-heat-treated diet induced significantly lower insulin sensitivity and plasma concentrations of long-chain n-3 (omega-3) fatty acids and vitamins C and E [-17% (P < 0.002), -13% (P < 0.0001), and -8% (P < 0.01), respectively]. However, concentrations of plasma cholesterol and triglycerides increased [+5% (P < 0.01) and +9% (P < 0.01), respectively].

CONCLUSIONS

A diet that is based on high-heat-treated foods increases markers associated with an enhanced risk of type 2 diabetes and cardiovascular diseases in healthy people. Replacing high-heat-treatment techniques by mild cooking techniques may help to positively modulate biomarkers associated with an increased risk of diabetes mellitus and cardiovascular diseases.

Ultra high temperature treatment, but not pasteurization, affects the postprandial kinetics of milk proteins in humans

Although the chemical and physical modifications to milk proteins induced by technological treatments have been characterized extensively, their nutritional consequences have rarely been assessed in humans. We measured the effect of 2 technological treatments on the postprandial utilization of milk nitrogen (N), pasteurization (PAST) and ultra high temperature (UHT), compared with microfiltration (MF), using a sensitive method based on the use of milk proteins intrinsically labeled with (15)N. Twenty-five subjects were studied after a 1-wk standardization of their diet. On the day of the investigation, they ingested a single test meal corresponding to 500 mL of either MF, PAST, or UHT defatted milk. Serum amino acid (AA) levels as well as the transfer of (15)N into serum protein and AA, body urea, and urinary urea were determined throughout the 8-h postprandial period. The kinetics of dietary N transfer to serum AA, proteins, and urea did not differ between the MF and PAST groups. The transfer of dietary N to serum AA and protein and to body urea was significantly higher in UHT than in either the PAST or MF group. Postprandial deamination losses from dietary AA represented 25.9 +/- 3.3% of ingested N in the UHT group, 18.5 +/- 3.0% in the MF group, and 18.6 +/- 3.7% in the PAST group (P < 0.0001). The higher anabolic use of dietary N in plasma proteins after UHT ingestion strongly suggests that these differences are due to modifications to digestive kinetics and the further metabolism of dietary proteins subsequent to this particular treatment of milk.

Comparative analysis of ascorbic acid in human milk and infant formula using varied milk delivery systems

Background

The expression of human milk for later use is on the rise. Bottle systems are used to deliver the expressed milk. Research has shown that storage of both human milk and artificial baby milk, or infant formula, leads to a loss of ascorbic acid (commonly called Vitamin C). As milk is removed from the bottle during feeding and replaced by ambient air, it is unknown if loss of ascorbic acid occurs during the course of a feeding. The purpose of this study is to investigate the effect of the milk delivery system on levels of ascorbic acid in human milk and infant formula. The objectives are to 1) determine changes in ascorbic acid concentration during a 20 minute "feed," 2) determine if there is a difference in ascorbic acid concentration between delivery systems, and 3) evaluate if any differences are of clinical importance.

Methods

Commonly available bottles were used for comparison of bottle delivery systems. Mature human milk was standardized to 42 mg/L of ascorbic acid. Infant formula with iron and infant formula with docosahexanoic acid were used for the formula samples. Each sample was analyzed for ascorbic acid concentration at baseline (0), 5, 10, 15, and 20 minutes. Each collection of samples was completed in triplicate. Samples were analyzed for ascorbic acid using normal-phase high performance liquid chromatography.

Results

Ascorbic acid concentration declined in all bottle systems during testing, Differences between the bottle systems were noted. Ascorbic acid concentrations declined to less than 40% of recommended daily intake for infants in 4 of the bottles systems at the 20 minute sampling.

Conclusion

The bottle systems used in this study had measurable decreases in the mean concentration of ascorbic acid. More research is needed to determine if the observed decreases are related to lower plasma ascorbic acid concentration in infants exclusively bottle fed. The decrease of ascorbic acid concentration observed in both human milk and infant formula using varied milk delivery systems may be of clinical importance. For infants who rely solely on bottle feeds there may be increased risk of deficiency. Bottle shape, size, and venting should be considered.

Stability of antioxidants in an apple polyphenol-milk model system

The stability of antioxidants in an apple polyphenol-milk model system was examined. The model system consisted of skim milk fortified with pH-neutralised apple polyphenols (AP, 0-200mg per 100ml milk), with or without ascorbic acid (100mg per 100ml milk). Physical and chemical changes were evaluated after thermal treatment (120°C, 5min) and oxidative storage (20°C and 38°C, up to 12 weeks). Antioxidant capacity was determined using both oxygen radical absorbance capacity (ORAC) assay and ferric reducing antioxidant power (FRAP) assay. Significant antioxidant capacity was detected in the presence of milk. Antioxidant capacity was retained during thermal treatment but decreased slowly during storage. The concentration of ascorbic acid decreased rapidly, and was close to zero after 2-week storage at 38°C or 10-week storage at 20°C. The brownness of the polyphenol-milk system increased over storage duration of 0-12 weeks; this effect was retarded by the addition of ascorbic acid. This high polyphenol-milk has demonstrated good physical stability.

Potential of front face fluorescence associated to PLS regression to predict nutritional parameters in heat treated infant formula models

This work shows that front face fluorescence spectroscopy associated to partial least squares (PLS) calibration is a fast and simple method to assess the nutritional impact of heat treatment on milk samples. Emission spectra of tryptophan (Trp) and of advanced Maillard products (AMP) were recorded on intact milk samples non-heated and heated at seven temperatures (72 degrees C, 80 degrees C, 87 degrees C, 95 degrees C, 100 degrees C, 110 degrees C and 115 degrees C) for six different times (from 2 min to 9.5 min) by means of front face fluorescence. PLS calibrations were constructed in order to indirectly quantify three indicators: vitamin C, protein denaturation and accumulation of Maillard products using the fluorescence of advanced Maillard products and soluble tryptophan method (FAST). The prediction models allowed obtaining an estimation of these indicators with a relative error of 12% for vitamin C and about 18% for the FAST index and soluble whey protein ratio.

Impact of nutrition on ageing and disease

PURPOSE OF REVIEW

The globe is suffering a tsunami of chronic diseases, affecting especially the elderly and those with a dysfunctioning immune system. The fundamental principles of optimal health and optimal ageing are abstaining from smoking, modest alcohol consumption, regular physical exercise and a diet rich in fish and plants and low in condensed calories, sugar and dairy products.

RECENT FINDINGS

Dietary supply and production of advanced glycation end products leads to the accumulation of these products in the tissues and is strongly associated with ageing of the vascular endothelium, nervous system, eyes and other vital organs. Telomeres, which are not involved in DNA repair, remain unrepaired and loose with time. A decline in innate and acquired immunity is seen with increasing age and maintenance of low basal immune activity (degree of inflammation) seems important for health and longevity: 'people who are predisposed to weak inflammatory activity may live longer'.

SUMMARY

Supplementation with vitamins has little effect on ageing/prevention of chronic diseases, but antiinflammatory molecules like polyphenols are more effective, especially when combined with reduced intake of calorie-condensed foods. The effect of probiotics on ageing needs further exploration. The effects of caloric restriction, proven effective in other species to control aging and prolong lifespan, have not been fully explored in humans.