Whey proteins interact with lipids during autoxidation primarly via the production of reactive carbonyl species

Nowadays, it is well recognized that polyunsaturated fatty acids (PUFAs) can provide extensive nutritional and health benefits. Thus, ω-3 PUFAs have been considered to contribute to the prevention of several diseases. Recognition of the potential benefits of ω-3 fatty acids has stimulated increased interest towards the fortification of foods with oils rich in these particular fatty acids. However, enrichment of food products with such unsaturated fatty acids should be carefully evaluated since they are highly susceptible to oxidation. Moreover, exposure of proteins to peroxidizing lipids or their secondary breakdown products may induce severe changes in proteins, including polymerization, insolubilization and formation of lipid – protein complexes. Several amino acids, but mainly mainly cysteine, methionine, histidine, tyrosine and lysine are affected by the secondary lipid oxidation products, therefore leading to reductions of their availability. The objective of this study was to characterize changes induced in whey protein isolate (a mixture of α-lactalbumin and β-lactoglobulin) through oxidation with oils with different unsaturation degrees and different initial oxidation status. The incubation of whey proteins with oils caused an increase in protein bound carbonyl content through the interaction of lipid oxidation products with the amino acids. Changes in the amino acid composition were therefore also observed mostly upon incubation with fish and highly oxidized soybean oil. Interaction of proteins with lipid oxidation products was taking place via interaction of the reactive carbonyl species formed thus leading to protein aggregates formation. Protein aggregation was therefore one of the most prominent consequence of the interaction of whey proteins with oxidizing lipids

Stability of whey protein derived peptides upon severe protein glycation

Cow’s milk and dairy products are major nutrients in the human diet, especially during infancy. Though at one time whey proteins were considered as by-product of the cheese making process, nowadays, due to their wide ranging nutritional, biological, and functional properties, whey proteins are often used in food technology as low-cost protein ingredients. However, whey-protein fractions, such as β-lactoglobulin (β-LG) and α-lactalbumin (α-LA) represent the major allergens in cow’s milk. Therefore, the use of whey proteins in food might pose a serious threat to the milk allergic consumers. It is well reported that food processing may modify the allergenicity and detectability of proteins. This can be due to hydrolysis or chemical reactions with other food components (carbohydrates, fatty acids etc), leading to modification or destruction of the allergen’s structure. Therefore, the objective of this study was in the first stage to investigate the influence of glycation on the molecular changes induced in whey proteins. This was done with a special focus on the modifications induced on the lysine residues, free amino groups, the formation of protein bound carbonyls, formation of fluorescent compounds and brown polymers and on the protein aggregation. Matrix-assisted laser desorption/ionization - time of flight mass spectrometry (MALDI-TOF MS) was used to get a better insight into the molecular changes that took place on the protein level. Unexpectedly, this study led to the identification of protein segments in the epitope region that remained unmodified during the experiments that mimic typical food processing conditions. The 57Val – Lys76 and 31Val – Arg56 from β–LG, remained unchanged disregarding the severe heating treatment in the presence of glucose and bulk proteins and they could be identified by either direct MALDI-TOF MS and MS/MS or after a more tedious separation using reversed phase chromatography. It is proposed that these peptide segments can be used as analytical targets for the development of more robust methods for the assessment of the presence of whey proteins in processed foodstuffs. Moreover, MALDI-TOF MS and MS/MS holds potential to be used as a screening tool for the identification of such stable peptides

Water and oil signal assignment in low-moisture mozzarella as determined by time-domain NMR T2 relaxometry

A time-domain H-1 nuclear magnetic resonance relaxometry method was elaborated for the rapid microstructural characterization of mozzarella cheese. For this purpose, there is a strong need to know how the experimentally determined T-2 relaxation time distribution can be related to specific constituents in mozzarella. In this study, a detailed investigation is offered for fresh and aged low-moisture mozzarella cheese, often applied as a pizza cheese, by application of both a conventional Carr-Purcell-Meiboom-Gill (CPMG) sequence and a free-induction decay CPMG (FID-CPMG) sequence. The relaxation behavior was further elucidated by addition of deuterium oxide and by mild heat treatment of samples. The relaxation times of water protons in mozzarella were found to range from a few microseconds to some tens of milliseconds (in aged mozzarella) or to about hundred milliseconds (in fresh mozzarella). The upper limit of the T-2 distribution can even be extended to the seconds range upon releasing water protons from the mozzarella matrix using a mild heat treatment or upon addition of deuterated water. Both stimuli also provided evidence for the absorption of water into the cheese matrix. The potential release and uptake of water demonstrated that mozzarella acts as a very dynamic system during production and storage. The detected differences in the behavior of the water fraction between fresh and aged low-moisture mozzarella might be utilized to study the influence of either production and/or storage conditions on the cheese ripening process

LAZ3 (lymphoma associated zinc finger on chromosome 3)

Review on LAZ3 (lymphoma associated zinc finger on chromosome 3), with data on DNA, on the protein encoded, and where the gene is implicated

Seasonal variations in the functional performance of industrial low-moisture part-skim mozzarella over a 1.5-year period

Seventy-five blocks of low-moisture part-skim (LMPS) Mozzarella cheese were procured from an industrial cheese plant, and the relationships between the physicochemical and functional properties were evaluated during refrigerated storage. In total, cheeses were obtained from 1 cheese vat on 7 different production dates, at two- to four monthly intervals, over a 1.5 year period; all cheeses were made using a standard recipe. The cheeses were held at 4°C for 0, 1, 2, 4, 8, 16 or 32 d and assayed for composition, primary proteolysis, serum distribution, texture profile analysis, heat-induced changes in viscoelastic behavior, cheese extensibility and melt characteristics. The results demonstrated a substantial increase in serum uptake by the calcium-phosphate para-casein matrix between 1 and 16 d of storage with a concomitant improvement in the functional performance of the cheese. Extending the storage time to 32 d resulted in further changes in the functional quality, concurrent with ongoing increases in protein hydration and primary proteolysis. Differences in the measured characteristics between the cheeses obtained on different sampling occasions were evident. Principal component analysis separated the cheeses based on their variance in functional performance, which was found to be correlated mainly with the calcium content of the cheese. The results indicate that the manufacturing process should be tightly controlled to minimize variation in calcium content, and enhance the quality consistency of the cheese

Impact of freezing on the physicochemical and functional properties of low–moisture part–skim mozzarella

peer-reviewedLow–moisture part–skim (LMPS) mozzarella cheeses were held at 4 °C for 0, 2 or 8 d before freezing to −20 °C. The cheeses were frozen at a rate of 0.6, 2.0 or 8.0 °C h−1 and held frozen at −20 °C for 1, 6, 12 or 44 weeks. After freezing, cheeses were stored at 4 °C for 16–37 d, resulting in a total storage time at 4 °C (before and after freezing) of 24–37 d (frozen–thawed mozzarella). Control mozzarella was stored at 4 °C for 25–37 d. The control and frozen–thawed cheeses were assayed for composition, primary proteolysis, moisture distribution, texture profile analysis and melting characteristics after similar storage times at 4 °C. Freezing under the evaluated conditions resulted in reduced firmness of the unheated cheese but did not significantly affect the properties of the heated cheese. The results suggest that freezing may be effectively applied to control or extend the functional shelf–life of LMPS mozzarella shipped to long–distance markets.Flanders' FOO

Determining the Effects of Manganese Source and Level on Growth Performance, Carcass Characteristics, and Economics of Growing-Finishing Pigs

A total of 1,944 mixed sex growing-finishing pigs (PIC; 337 × 1050; initially 76.0 ± 3.71 lb) were used in a 107-d growth trial to determine the effects of increasing levels of two different manganese sources on the performance of growing-finishing pigs from 76 to 295 lb. Pens were assigned to 1 of 6 treatments in a randomized complete block design with initial weight as a blocking factor. There were 12 replicate pens per treatment and 27 pigs per pen. The experimental diets were corn-soybean meal-based and were fed in 4 phases. The 6 dietary treatments were arranged in a 2 × 3 factorial with main effects of Mn source, (MnSO4 or Mn hydroxychloride: IBM), and 3 added Mn concentrations (8, 16, or 32 ppm). The trace mineral premix was formulated to contain no added Mn. There were no Mn source × level interactions (P \u3e 0.10) observed for any of the individual dietary phases. For the overall period (d 0 to 107), there was a Mn source × level interaction (quadratic, P = 0.048) for feed efficiency (F/G), with F/G improving for the lowest and highest level of Mn supplementation from IntelliBond M (IBM) whereas F/G tended to improve with increasing Mn from MnSO4. For the main effect of level, the intermediate dietary level of Mn had the poorest (quadratic, P \u3c 0.097) average daily gain (ADG) in phases 1 and 4, which resulted in the poorest overall ADG and final body weight (BW) (quadratic, P \u3c 0.05). There was no evidence for differences in pigs fed either Mn source for ADG or ADFI. There was a tendency for Mn source × level interaction (quadratic, P = 0.075) for carcass yield, where yield did not change by added MnSO4, but increased then decreased for pigs fed diets with IBM. Loin depth increased (linear, P = 0.035) for pigs fed increasing amounts of Mn from MnSO4 but decreased when Mn was increased from IBM. Pigs fed the intermediate level of Mn also had the lightest HCW (quadratic, P = 0.071) and decreased loin depth (quadratic, P = 0.044). No differences were observed in economics except for revenue (quadratic, P = 0.093) being the lowest for pigs fed the intermediate level of Mn. No evidence of difference (P \u3e 0.10) was observed for Mn source × level inter- actions on the concentration of Cu, Mn, and Zn in the liver. Manganese concentration increased (linear, P = 0.015) as added Mn increased and liver Mn tended to be greater (P = 0.075) when Mn was supplied by MnSO4 compared to IBM. There was no evidence of difference (P \u3e 0.10) for Mn source or level influence on liver Cu and Zn concentrations. In conclusion, these data suggest little difference among Mn sources but did show improvements in growth performance for dietary levels of 8 and 32 ppm of Mn compared with 16 ppm. Further research is needed to understand why pigs fed the intermediate level of Mn had decreased ADG