Enriched Milk Research Articles

Determination of Rennet Clotting Time by Texture Analysis Method

In this study, texture analysis method was used for the determination of rennet flocculation time (tfloc) and rennet clotting time (tclot) of rennet-induced reconstitued milk samples with different CaCl2 concentrations. The rennet flocculation time (RFT) and rennet clotting time (RCT) were also determined by using the Berridge test and sensory evaluation. The hardness value versus renneting time curves derived from texture analysis gave a good modified exponential relationship for each CaCl2 concentration and the curves were used to calculate flocculation time and clotting time parameters. It was found that the parameters (tfloc and tclot) appeared strongly correlated with RFT and RCT, respectively. Texture analysis was proved as a suitable method to control the rennet-induced coagulation and determine the rennet clotting time. It was also determined that enrichment of milk with CaCl2 leaded to a decrease in flocculation and clotting times and an increase in rate of clotting and gel hardness.

Additional benefit in CVD risk indices derived from the consumption of fortified milk when combined with a lifestyle intervention.

The current study aimed to evaluate the effect of fortified milk combined with a lifestyle and counselling programme on several CVD risk factors after a 3-month dietary intervention. Hypercholesterolaemic adults were randomized to a group supplemented with low-fat milk that was enriched with phytosterols, α-linolenic and linoleic fatty acids, vitamins and antioxidants (enriched milk group, EMG: n 40), a placebo milk group (PMG: n 36) or a control group (CG: n 25). The EMG and PMG consumed respectively 500 ml of enriched milk or placebo milk daily and attended biweekly counselling sessions over a 3-month period. Harokopio University, Athens, Greece. A sample of 101 hypercholesterolemic adults aged 40-60 years. Regarding lifestyle changes, total and saturated fat intakes decreased significantly in both intervention groups compared with the CG (P < 0·005). Furthermore, total steps were increased (P = 0·029) and BMI was decreased (P = 0·017) significantly in both intervention groups compared with the CG. Regarding biochemical indices, EPA content in erythrocyte membranes increased (P < 0·001) while serum C-reactive protein decreased (P = 0·003) significantly in both intervention groups compared with the CG. Finally, significant increases in plasma folic acid and vitamin B12 levels and a significant decrease in homocysteine levels were observed in the EMG compared with the PMG and CG (all P < 0·001). A favourable change in LDL cholesterol:HDL cholesterol was also observed in the EMG and tended to be significant compared with the PMG and CG (P = 0·066). The present study showed that consumption of fortified milk accompanied with lifestyle counselling induces extra benefits in terms of LDL cholesterol:HDL cholesterol and serum homocysteine levels.

Physicochemical and sensory properties of yogurt enriched with microencapsulated fish oil

Encapsulation of marine omega-3 oil by complex coacervation technique has been introduced as most effective approach to delay its oxidation and extend shelf life of ω(3)-enriched food products. Therefore, to produce enriched yogurt, fish oil containing long-chain omega-3 polyunsaturated fatty acids was microencapsulated in complex coacervates of gelatin/acacia gum. Then, the microcapsules were dried and their surface oil was extracted. Set yogurt was prepared by enriched milk with microcapsules powder. Physicochemical and sensory properties of enriched yogurt were measured during 21 days storage. Acidity, apparent viscosity and water holding capacity of enriched samples were higher and gel strength and amount of whey separation were lower compared to the control. The enriched yogurt samples were more yellowish compared to control. The peroxide value of free and encapsulated fish oil in enriched yogurt samples, after 22 days storage, were increased to 72% and 260%, respectively. Fish oil release of microcapsules was not detected by gas chromatography in extracted oil from enriched yogurt. Sensory results showed that untrained panelists evaluated overall acceptance of enriched yogurt with treated-fish oil microcapsules by lime juice as 'neither liked nor disliked to slightly liked'.

Enrichment of Milk with Conjugated Linoleic Acid by Supplementing Diets with Fish and Sunflower Oil

There is an increase interesting in enrichment of milk with Conjugated Linoleic Acid (CLA) due to its anti-oxidative and anti-carcinogenic properties. The objective of this study was to investigate the effect of supplementing diets fed to lactating goats with sunflower, fish oil and its blend. Eight lactating Nubian goats were fed a base diet (T1), diet supplemented with 2% sunflower oil (on dry matter (DM) basis) (T2), diet supplemented with 2% fish oil (T3) and diet supplemented with 2% sunflower and fish oil (T4) for 84 day. Milk composition milk fat, protein (%) decreased in T2, T3 and T4 compared with control (T1) while there was no significant differences between treatments in milk lactose content. CLA content in milk fat was higher in response to fish oil or sunflower and fish oil blend compared with control (T1). The results indicated that supplementing diets fed to lactating goats with sunflower, fish oil increased CLA contents in the milk 2-4 times than control.

The antioxidative effect of lipophilized rutin and dihydrocaffeic acid in fish oil enriched milk

AbstractThe antioxidative effect of phenolipids was evaluated in fish oil enriched milk emulsions as a model for a complex food system. Two different phenolipids modified from dihydrocaffeic acid (with C8 or C18:1) and rutin (with C12 or C16) were evaluated. Both dihydrocaffeate esters and rutin laurate showed significantly better antioxidant properties in milk emulsion compared with the original phenolics. However, rutin palmitate only performed slightly better as antioxidant than rutin. The results with rutin indicated that a cut‐off effect exists in relation to the alkyl chain length with respect to optimal antioxidant activity in milk emulsions. Thus, the optimal alkyl chain length is at least below 16 carbon atoms, and maybe even less for rutin esters. For dihydrocaffeate esters it was not possible to conclude on a cut‐off effect in relation to alkyl chain length and antioxidative effect due to the almost similar antioxidant effect of the two phenolipids. However, there was a tendency towards octyl dihydrocaffeate being slightly more efficient than oleyl dihydrocaffeate.Practical application: The finding that phenolipids are better antioxidants in milk emulsions than the original phenolic acid provides new knowledge that can be used to develop new antioxidant strategies to protect foods against lipid oxidation. However, the results indicate that both optimization of alkyl chain length for each type of phenolic, and optimization for each type of emulsion will be necessary in order to get the best oxidative stability of an emulsion with these phenolipids. Use of efficient antioxidants may lower the amount of antioxidant needed to protect against lipid oxidation and may in addition decrease the costs.

Cerium in human milk samples and its transfer from blood to milk: Is there an elevated nutritional risk for breast-fed babies?

The general population is increasingly exposed to cerium (Ce), which is contained in industrial products or is present as nuclear Ce fission products. Some studies suggested a link between elevated Ce levels and endomyocardial fibrosis. Since breast milk is the optimal, and directly after birth, usually the sole nutrition for newborns, exposure of females to Ce and its transfer to infants by breast-feeding is of concern in neonate protection. Consequently, the transfer rate of Ce from blood to breast milk is of interest for elucidating the Ce exposure of infants. Biomonitoring of paired serum and breast milk samples provides such information about Ce transfer to human milk. Therefore, this study is aimed at clarification of the relationship between Ce in human milk and serum from respective mothers for elucidating Ce enrichment in human milk with possible nutritional risk for newborns. As a prerequisite a strictly quality-controlled Ce determination method applicable to very low Ce concentration was developed, and its figures of merit were determined and found to be sufficient for our purpose. It turned out that Ce concentration in milk from Munich (Germany) and Madrid (Spain) showed a median of 13 ng/L. Ce concentrations in serum were at limit of quantification (LOQ) 10 ng/L (Munich) or 21.6–70.3 ng/L (Madrid), suggesting a higher Ce intake in Madrid. No enrichment from blood to milk was seen, and no elevated nutritional risk for breast-fed babies from Ce was found. Ce in serum, but not in milk, could indicate environmental Ce.

Enriching milk fat with n−3 polyunsaturated fatty acids by supplementing grazing dairy cows with ruminally protected Echium oil

Echium oil is a naturally rich source of stearidonic acid (SDA; C18:4 n−3), an n−3 polyunsaturated fatty acid ( n−3 PUFA) which is a precursor to the long chain (LC) n−3 polyunsaturated fatty acids (LC n−3 PUFA) eicosapentaenoic (EPA, C20:5 n−3) and docosahexaenoic (DHA, C22:6 n−3). The latter are LC n−3 PUFA for which there is accumulating evidence for positive cardiovascular health claims in human consumers. To determine the extent to which SDA supplementation can enrich milk fat with EPA and DHA, we supplemented 5 dairy cows on irrigated pasture with Echium oil for 10 d. The oil supplement was ruminally protected against biohydrogenation by using a protein–aldehyde matrix. Milk samples were collected during supplementation and 1, 2 and 30 d after supplementation ceased. Echium oil supplementation had no effect on levels of milk crude protein, fat, lactose and solids-not-fat. Average daily milk yield gradually declined as the period of supplementation progressed, and returned to pre-supplementation period levels after withdrawal of the supplement. The proportions of α-linolenic acid (ALA, 18:3 n−3), SDA, EPA and total n−3 PUFA in milk fat increased in response to supplementation. The initial (Day 1) and final (Day 10) concentrations (in mg/l) of ALA, SDA, EPA and DPA in whole milk were 463 ± 29.2 versus 877 ± 63.1, 38 ± 8.6 versus 144 ± 12.4, 13 ± 6.2 versus 76 ± 9.0 and 45 ± 4.5 versus 65 ± 4.3, respectively. ALA, SDA, EPA and total n−3 PUFA concentrations increased linearly with increasing days of supplementation, while increases in DPA concentrations were curvilinear with a 3–4 d delay in their rise. DHA was not detected in milk fat. In terms of fatty acid yield/cup (i.e., 250 ml) of whole milk, enrichment of milk with EPA amounted to an increase from around 3.1–13.9 mg. As there was no change in DHA content, the long-chain n−3 PUFA content based on EPA alone was less than half of the cut-off point for omega-3 “source” claim (30 mg EPA + DHA per human serving) for foods in Australia. However, the total n−3 PUFA content of milk increased from 559 ± 41.0 to 1162 ± 82.4 mg/l. Data suggest that this oil containing SDA enriched milk with EPA, but not DHA. Dose response and large scale studies are needed to determine the optimal dietary inclusion rate and the commercial feasibility of SDA-containing oils as a means of increasing n−3 fatty acids in dairy cow milk.

Bioavailability of vitamin B12 in cows' milk

The natural source of vitamin B₁₂ in human diets comes from animal products. For example, one glass (250 ml) of milk provides approximately 50 % of the RDA (2·4 μg/d). It was hypothesised that the provision of vitamin B₁₂ from milk is more efficiently absorbed than the synthetic form used in vitamin supplements. Pigs (n 10) were used as a model for intestinal absorption of vitamin B₁₂ in humans to compare the net fluxes of vitamin B₁₂ across the portal-drained viscera (PDV; an indicator of intestinal absorption) after ingestion of meals complemented with conventional and vitamin B₁₂-enriched (via injections to cows) milk (raw, pasteurised or microfiltrated) or with equivalent amounts of cyanocobalamin, the synthetic form used in supplements or unsupplemented. Net flux of vitamin B₁₂ across PDV after the ingestion of milk was positive, though not influenced by milk enrichment (P>0·3) or technological processes (P = 0·8) and was greater than after ingestion of equivalent amounts of cyanocobalamin (cyanocobalamin v. all milk, P ≤ 0·003). In fact, net fluxes of this vitamin were not different from 0 after either cyanocobalamin or the meal devoid of vitamin B₁₂ (unsupplemented v. cyanocobalamin, P = 0·7). The cumulative PDV fluxes during the 24 h following ingestion of meals complemented with milk varied from 5·5 to 6·8 μg. These values correspond to an efficiency of intestinal absorption of vitamin B₁₂ from milk varying between 8 and 10 %. Therefore, vitamin B₁₂, which is abundant in cows' milk, is also substantially more available than the most commonly used synthetic form of this vitamin.

Increased palmitoyl-myristoyl-phosphatidylcholine in neonatal rat surfactant is lung specific and correlates with oral myristic acid supply

Surfactant predominantly comprises phosphatidylcholine (PC) species, together with phosphatidylglycerols, phosphatidylinositols, neutral lipids, and surfactant proteins-A to -D. Together, dipalmitoyl-PC (PC16:0/16:0), palmitoyl-myristoyl-PC (PC16:0/14:0), and palmitoyl-palmitoleoyl-PC (PC16:0/16:1) make up 75-80% of mammalian surfactant PC, the proportions of which vary during development and in chronic lung diseases. PC16:0/14:0, which exerts specific effects on macrophage differentiation in vitro, increases in surfactant during alveolarization (at the expense of PC16:0/16:0), a prenatal event in humans but postnatal in rats. The mechanisms responsible and the significance of this reversible increase are, however, not understood. We hypothesized that, in rats, myristic acid (C14:0) enriched milk is key to lung-specific PC16:0/14:0 increases in surfactant. We found that surfactant PC16:0/14:0 in suckling rats correlates with C14:0 concentration in plasma chylomicrons and lung tissue triglycerides, and that PC16:0/14:0 fractions reflect exogenous C14:0 supply. Significantly, C14:0 was increased neither in plasma PC, nor in liver triglycerides, free fatty acids, or PC. Lauric acid was also abundant in triglycerides, but was not incorporated into surfactant PC. Comparing a C14:0-rich milk diet with a C14:0-poor carbohydrate diet revealed increased C14:0 and decreased C16:0 in plasma and lung triglycerides, respectively. PC16:0/14:0 enrichment at the expense of PC16:0/16:0 did not impair surfactant surface tension function. However, the PC profile of the alveolar macrophages from the milk-fed animals changed from PC16:0/16:0 rich to PC16:0/14:0 rich. This was accompanied by reduced reactive oxygen species production. We propose that nutritional supply with C14:0 and its lung-specific enrichment may contribute to decreased reactive oxygen species production during alveolarization.

Nutrient Enrichment of Mother's Milk and Growth of Very Preterm Infants After Hospital Discharge

To determine if the addition of a multinutrient human milk fortifier to mother's milk while breastfeeding very preterm infants after hospital discharge is possible and whether it influences first-year growth. Of a cohort of 320 infants (gestational age: 24-32 weeks; birth weight: 535-2255 g), breastfed infants (65% [n = 207]) were randomly assigned shortly before hospital discharge to receive either unfortified (n = 102, group A) or fortified (n = 105, group B) mother's milk until 4 months' corrected age (CA). The remaining infants were bottle-fed with a preterm formula (group C). Follow-up was performed at term and at 2, 4, 6, and 12 months' CA. Mean duration of breastfeeding after term was not significantly different between groups A and B (11.8 and 10.6 weeks, respectively). Weight, length, and head circumference were not significantly different between groups A and B at 12 months' CA. Compared with groups A and B, infants in group C had a higher increase in weight z score until term and in length z score until 6 months' CA. At 12 months' CA, boys in group C were significantly longer and heavier compared with those in groups A and B, whereas girls in group C were longer and heavier compared with those in group A only. A higher protein intake was related to a higher serum urea nitrogen level and growth. Fortification of mother's milk after hospital discharge while breastfeeding very preterm infants was possible without influencing breastfeeding duration but did not significantly influence growth parameters at 1 year of age compared with unfortified mother's milk.

Bovine milk fat enriched in conjugated linoleic and vaccenic acids attenuates allergic dermatitis in mice

Orally administered milk fat enriched in conjugated linoleic acid (CLA) and trans-vaccenic acid (VA) ('enriched milk fat'), produced by supplementing the diet of pasture-fed cows with fish and sunflower oil, has been shown previously to suppress the development of allergic airway disease in mice. To investigate whether topical or oral application of enriched milk fat and its two major fatty acids cis-9, trans-11 CLA (c9,t11-CLA) and VA inhibit allergic dermatitis in mice. Allergic dermatitis was induced in C57BL/6 mice by epicutaneous sensitization of tape-stripped skin with ovalbumin (OVA). Enriched milk fat and its two major fatty acids were either topically applied to the OVA-sensitized skin, or orally fed to mice by supplementation of the diet. Blood and skin tissues were collected for analysis after the third skin sensitization. Both topical and oral administration of enriched milk fat and its two major fatty acids led to significant suppression of allergic dermatitis as evidenced by reduced clinical and histological scores of affected skins, infiltration of inflammatory cells, and circulating allergen-specific IgE levels, compared with treatment with normal milk fat or the base control diet. C9,t11-CLA and VA individually inhibited multiple facets of allergic dermatitis when topically applied, and their combination produced a strong additive effect. Enriched milk fat, and its two major fatty acids c9,t11-CLA and vaccenic acid attenuate allergic dermatitis in mice.

Nitrogen partitioning and isotopic fractionation in dairy cows consuming diets based on a range of contrasting forages

Nine multiparous Holstein-Friesian cows (initially 97 d in milk), were used in a 3×3 lattice square design experiment with 4-wk periods. All cows received 4kg/d concentrates and dietary treatments were based on silages offered ad libitum: perennial ryegrass (PRG); timothy (TIM); tall fescue (TF); red clover (RC); red clover/corn silage mixture [40/60 on a dry matter (DM) basis; RCC]; red clover/whole-crop oat silage mixture (40/60 on a DM basis; RCO); or red clover/whole-crop oat silage mixture (25/75 on a DM basis; ORC). The remaining treatments were based on RCO with feed intake restricted to the level of PRG (RCOr) or with a low protein concentrate (50/50 mixture of barley and molassed sugar beet pulp; RCOlp). Experiment objectives were to evaluate diet effects on N partitioning and N isotopic fractionation. Yields of milk and milk protein were consistently high for diets RC, RCC, and RCO and low for the diets based on poorly ensiled grass silages. Restriction of intake (RCOr) and inclusion of a higher proportion of whole-crop oat silage (ORC) and the low-protein concentrate (RCOlp) led to some loss of production. Diet had little effect on milk fat, protein, and lactose concentrations: low concentrations of milk protein and lactose reflect the restricted energy intakes for all treatments. The highest diet digestibilities were measured for RC and PRG, whereas increasing inclusion of the whole-crop oat silage (0, 60, and 75% of forage DM) led to a marked decrease in diet digestibility (0.717, 0.624, and 0.574g/g, respectively). Urinary excretion of purine derivatives, an indicator for rumen microbial protein synthesis, was significantly higher for RCC than for TIM and TF. Nitrogen intake ranged between 359 and 626g/d (treatment means). Partitioning of N intake to feces and urine was closely related to N intake, although urinary N losses were less than predicted from N intake for the 60/40 mixtures of cereal silage and red clover silage. The 15N content of milk, urine, and feces were all influenced by diet 15N content. Isotopic fractionation meant that feces and milk were enriched and urine was depleted in 15N relative to the diet. Significant relationships were observed between the extent of enrichment of urine, feces, and milk, suggesting some commonality in fractionation pathways. The trend for the lowest 15N enrichment in milk protein occurring in diets with low N-use efficiency (milk N/feed N) was contrary to expectations, possibly because of endogenous contributions to milk protein or fractionation when dietary ammonia was incorporated into microbial protein.

Properties of set-style skim milk yoghurt as affected by an enzymatic or Maillard reaction induced milk protein oligomerisation

Protein oligomers (2.9 × 10 4–3.0 × 10 5 g/mol) were introduced into yoghurt in amounts of 15–37% of the total protein by an enzymatic modification of proteins in yoghurt milk by lactoperoxidase, laccase or glucose oxidase as well as by a dry matter increase of yoghurt milk with sodium caseinate/lactose, sodium caseinate/pectin and total milk protein/lactose Maillard products. Yoghurt from enzymatically treated milk was characterised by an up to 10% lower acidity, up to 47% diminished gel strength and up to 18% decreased whey drainage than yoghurt from untreated milk. Yoghurt from protein/saccharide Maillard product enriched milk exhibited up to 4% reduced acidity, up to 27% increased acetic aldehyde content as well as up to 58% decreased whey drainage in relation to yoghurt from untreated protein/saccharide mixture enriched milk. Sensorically, yoghurt from enzymatically treated milk as well as from protein/saccharide Maillard product enriched milk was described by an even and whey-draining appearance, by a soft, homogeneous and creamy consistency as well as by a mild, less yoghurt characteristic taste and smell. This study for the first time presents an overview over the impact of novel protein oligomerisation techniques on physicochemical and sensory properties of yoghurt in regard to possible practical applications of an enzymatic as well as Maillard reaction induced oligomerisation in complex food systems.

Microbial inactivation and shelf life comparison of ‘cold’ hurdle processing with pulsed electric fields and microfiltration, and conventional thermal pasteurisation in skim milk

Thermal pasteurisation (TP) is the established food technology for commercial processing of milk. However, degradation of valuable nutrients in milk and its sensory characteristics occurs during TP due to substantial heat exposure. Pulsed electric fields (PEF) and microfiltration (MF) both represent emerging food processing technologies allowing gentle milk preservation at lower temperatures and shorter treatment times for similar, or better, microbial inactivation and shelf stability when applied in a hurdle approach compared to TP. Incubated raw milk was used as an inoculum for the enrichment of skim milk with native microorganisms before PEF, MF, and TP processing. Inoculated milk was PEF-processed at electric field strengths between 16 and 42kV/cm for treatment times from 612 to 2105μs; accounting for energy densities between 407 and 815kJ/L, while MF was applied with a transmembrane flux of 660L/h m2. Milk was TP-treated at 75°C for 24s. Comparing PEF, MF, and TP for the reduction of the native microbial load in milk led to a 4.6 log10 CFU/mL reduction in count for TP, which was similar to 3.7 log10 CFU/mL obtained by MF (P≥0.05), and more effective than the 2.5 log10 CFU/mL inactivation achieved by PEF inactivation (at 815kJ/L (P<0.05)). Combined processing with MF followed by PEF (MF/PEF) produced a 4.1 (at 407 and 632kJ/L), 4.4 (at 668kJ/L) and 4.8 (at 815kJ/L) log10 CFU/mL reduction in count of the milk microorganisms, which was comparable to that of TP (P≥0.05). Reversed processing (PEF/MF) achieved comparable reductions of 4.9, 5.3 and 5.7 log10 CFU/mL (at 407, 632 and 668kJ/L, respectively (P≥0.05)) and a higher inactivation of 7.1 log10 (at 815kJ/mL (P<0.05)) in milk than for TP. Microbial shelf life of PEF/MF-treated (815kJ/L) and TP-treated milk stored at 4°C was analysed over 35days for total aerobic; enterobacteria; yeasts and moulds; lactobacilli; psychrotroph; thermoduric psychrotroph, mesophilic, and thermophilic; and staphylococci counts. For both PEF/MF and TP-treated milk an overall shelf stability of 7days was observed based on total aerobic counts (P≥0.05). Milk hurdle processing with PEF/MF at its most effective treatment parameters produced greater microbial inactivation and overall similar shelf stability at lower processing temperatures compared to TP. With higher field strength, shorter treatment time, larger energy density, and rising temperature the efficacy of PEF/MF increased contrary to MF/PEF. Thus, PEF/MF represents a potential alternative for ‘cold’ pasteurisation of milk with improved quality.

Antioxidant activity of yoghurt peptides: Part 1- in vitro assays and evaluation in ω-3 enriched milk

The aim of the present study was to investigate important factors contributing to the high oxidative stability of fish-oil-enriched yoghurt, with particular emphasis on the possible antioxidative effects of peptides released during yoghurt fermentation. Yoghurt samples were stripped from sugars and lactic acid and subsequently fractionated by ultrafiltration using membranes with cut off sizes of 30 kDa, 10 kDa and 3 kDa. The fractions were tested for antioxidant activity by investigating the inhibition of oxidation in liposome model system, 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activity, iron-chelating activity, and reducing power. The lower molecular weight fractions were found to be more effective antioxidants than higher molecular weight fractions. The lower molecular fractions were further tested as antioxidants in fish-oil-enriched milk. On the basis of peroxide value, volatiles, tocopherol and sensory characteristics, the lower molecular weight fractions 3–10 kDa and <3 kDa showed protection against oxidation of fish oil to the same extent as caseinophosphopeptides. The oxygen content of the yoghurt was also found to be lower than that of milk. Thus our findings suggests that the higher oxidative stability of yoghurt might be due to antioxidant peptides released during the fermentation of milk by lactic acid bacteria and/or by the lower oxygen content of yoghurt, which subsequently reduces the oxidative stress of fish oil incorporated in the yoghurt. The results show that antioxidant peptides may be used as an ingredient in foods enriched with fish oils to increase their oxidative stability.

Creatine synthesis: the origin of creatine in rat milk

Creatine serves as an important energy buffer and shuttle system in cells. Approximately 1.7%/day of the body's creatine pool is spontaneously converted to creatinine and excreted in the urine. This must be replaced by a combination of diet and synthesis. During lactation there may be an additional requirement due to the provision of creatine to the milk. Our objectives were (1) to quantify milk creatine in lactating rats, (2) to determine the origin of milk creatine, and (3) to determine the activities of the enzymes of creatine synthesis in lactating rats. We determined the origin of milk creatine by administering 14C‐creatine to lactating rats, followed by determination of its isotopic enrichment in milk and plasma. Since these isotopic enrichments were identical, we conclude that milk creatine is extracted from the blood. Supporting this is our failure to find significant activities of the enzymes of creatine synthesis in mammary glands. Milk creatine amounted to about 13 μmol/day, which is equivalent to 25% of the creatine lost by conversion to creatinine. The first and limiting enzyme in creatine synthesis was not increased in activity during lactation; neither was the renal output of guanidinoacetate. We conclude that there is only a modest increase in the need to provide creatine during lactation and that this may be largely provided by hyperphagia when creatine is present in the food. Supported by CIHR grant 97851.Grant Funding Source: Canadian Institute for Health Research

Docosahexaenoic acid (DHA): From the maternal–foetal dyad to the complementary feeding period

The docosahexaenoic acid (DHA, C22:6n-3) status of infants at birth and maternal DHA intake during pregnancy are interconnected and associated with infants’ developmental performance. High-dosage supplementation of long-chain polyunsaturated fatty acids (LCPUFAs; particularly DHA) in mothers, started at mid-pregnancy, has been associated with long-term positive effects on intelligence quotient scores of neurodevelopment. Poor maternal and infant DHA status could partly contribute to the observed association between certain conditions and impaired developmental outcome. The dietary DHA enrichment of human milk seems to be functionally effective in breastfed infants only when lactating mothers start supplementation during pregnancy. Results from trials in artificially fed infants are dissimilar and could be related in part to uninvestigated covariates such as infant DHA status at birth and the individual genetic background. Nevertheless, DHA supplementation during the complementary feeding period seems to be effective in improving neurofunctional and visual performance.

Effect of antioxidant‐enriched foods on plasma: Phospholipid molecular species composition

AbstractThe dietary supplementation with antioxidant‐enriched foods was evaluated for the phospholipid (PL) class and molecular species composition of human plasma. Twenty healthy subjects were supplied with α‐tocopherol (13.7 mg/day) and coenzyme Q10 (19.4 mg/day) by enriched milk, a dessert, fruit juice and yogurt for 21 days. Phosphatidylcholine (85.2%) and sphingomyelin (10.9%) were the main PL in all samples. Differences among the contents of PL classes were not found. However, principal component analysis showed differences in the PL molecular species 2 h after the mid‐morning snack. An increase of phosphatidylinositol (PI) containing stearic/arachidonic (on average from 42.5 to 47.0%), stearic/docosahexaenoic (3.2 vs. 4.9%), oleic/arachidonic and palmitic/docosapentaenoic acid (2.4 vs. 3.7%) was observed. The decreasing species of PI were palmitic/linoleic (5.7 vs. 4.3%), palmitic/oleic (8.1 vs. 6.9%) and stearic/linoleic acid (17.4 vs. 13.8%) after the mid‐morning snack. Phosphatidylethanolamine (PE) species showed an opposite trend with respect to PI: A decrease was registered for stearic/arachidonic (17.0 vs. 15.8%), stearic/docosahexaenoic (7.2 vs. 4.9%), oleic/arachidonic and palmitic/docosapentaenoic acid (5.8 vs. 4.8%); an increase was observed for the PE species containing oleic/linoleic (5.5 vs. 7.5% on average after the mid‐morning snack), stearic/linoleic (19.7 vs. 23.4%) and stearic/oleic acid (11.4 vs. 13.9%).

The effect of dietary iodine supplementation in dairy goats on milk production traits and milk iodine content

Dairy products offer an important source of iodine for humans, particularly infants and children. An adequate iodine content in the diet of lactating animals must guarantee a suitable milk iodine concentration. In this experiment, the effects of iodine supplementation of dairy goat diets on the iodine concentration, milk yield, and milk composition of goat milk were studied. Thirty crossbred dairy goats of the Sarda population were divided into 3 groups supplemented with 0 (control group), 0.45 (group 1), or 0.90 (group 2) mg of KI/d per goat. The dose of KI (76.5% of iodine) was dissolved in water and orally administered with a syringe every day for 10 wk. Mean milk iodine concentrations were 60.1±50.5, 78.8±55.4, and 130.2±62.0μg/L (mean±SD) in the control group, group 1, and group 2, respectively. The extent of iodine enrichment in milk was approximately 31% in group 1 and 117% in group 2 compared with the control group. Milk yield was not influenced by KI supplementation and averaged 1,229, 1,227, and 1,179 g/d in groups 0, 1, and 2, respectively. Milk urea nitrogen concentration was significantly lower in the KI-supplemented groups (32 and 33 mg/dL in groups 1 and 2, respectively) than in the control group (37 mg/dL). Iodine supplementation of dairy goat diets can increase milk iodine content without adverse effects on milk production traits.

Lipid Oxidation in Functional Dairy Products

Functional dairy products are usually fortified or enriched with unsaturated lipids of known positive health effects, mainly in prevention of cardiovascular diseases and cancer. The main lipids used are omega-3 long-chain polyunsaturated fatty acids, conjugated linoleic acid and phytosterols. Lipid oxidation can occur during processing and storage of functional dairy products enriched with such unsaturated lipids and results in formation of undesirable offflavours and unhealthy compounds. This review highlights the importance of studying oxidative stability of functional dairy products in order to ensure the integrity of the original lipids and hence guarantee the quality and safety of functional dairy products. A survey of the recent literature shows that there is still scarce information on lipid oxidation in functional dairy products, in part due to its complexity in these multiphase food systems. Experimental protocols of most of the studies found start from enrichment of plain milk or dairy products with functional lipids, and examine oxidation along storage. Particular emphasis is placed in this review on discussion of the methods used for evaluation of oxidation. Among them, sensory evaluation is essential to ensure consumer acceptance, while quantitative analysis of non-volatile lipid oxidation compounds and antioxidants stand out as the most adequate methods to determine the lipid oxidation state in functional dairy products. Keywords: Lipid oxidation, functional dairy products, omega-3 fatty acids, conjugated linoleic acid (CLA), phytosterols