Non-protein Nitrogen Fraction Research Articles

Effect of Marinating Temperature of Atlantic Herring on Meat Ripening, Peptide Fractions Proportion, and Antioxidant Activity of Meat and Brine

The temperature has a significant effect on cathepsin activity, but the effect of temperature on the ripening of marinades, and the formation of protein hydrolysis products, is less studied than other technological factors. The results of this study showed that herring marinated at 2 °C showed a higher mass yield, but lower non-protein nitrogen (NPN), peptides, and free amino acid fraction content, than after marinating at 7 and 12 °C. The higher temperature increased the free amino acid content the most, and decreased the hardness, as measured via sensory assessment, of the marinated meat. This was confirmed by the hardness measurement in the texture profile analysis. The highest activity of cathepsins D and B in the meat was found at 7 °C, while cathepsin L was found at 2 °C. Increasing the temperature by 10 °C increased the diffusion/loss of nitrogenous substances from the meat to the brine by 36%. The meat and brine showed high antioxidant activity, which depended on the marinating temperature, and originated mainly from the 5–10 or <5 kDa fraction. The meat had a higher ABTS (2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonate) activity than the brine, opposite to the DPPH (2,2-diphenyl-1-picrylhydrazyl radical) activity, while the FRAP (Ferric Reducing Antioxidant Power) capacity was similar for meat and brine. The fractionation of the meat and brine extracts increased the antioxidant potential of FRAP and ABTS only for the brine. The most hydrophobic peptides were released during marinating at 7 °C. The meat and brine were dominated by 2–4 kDa peptides, followed by 4–6 and 0.5–2 kDa. The higher temperature favored a higher proportion of <4 kDa than >4 kDa peptides in the brine.

Role of Stingray (Himantura signifier) Non-Protein Nitrogenous Fraction on the Oxidative Stability of Lipid and Myoglobin.

Non-protein nitrogen (NPN) is abundant in stingray (Himantura signifier) muscle, which also has in vitro antioxidant activity. In this study, NPN from stingray muscle was further investigated for its antioxidant properties in lecithin liposome and oxymyoglobin model systems to validate its protective impact against lipid and myoglobin oxidations during storage for 120 min at various temperatures (4, 25, and 60 °C). NPN solution (10 ppm nitrogen) was added to the lecithin liposome system at different concentrations (0, 0.5, 1, 5, and 10% (v/v)) to investigate its effects on lipid stability by measuring the conjugated diene (CD), peroxide value (PV), and thiobarbituric acid reactive substances (TBARS) contents. In the oxymyoglobin system, NPN solution (10 ppm nitrogen) was also added at different concentrations (0, 0.5, 1, 5, and 10% (v/v)) to the oxymyoglobin solution in order to examine its effect on the stability of myoglobin by determining the contents of oxymyoglobin, metmyoglobin, and protein carbonyl. According to the findings, in all NPN concentrations, the system incubated at 4 °C had the lowest levels of lipid oxidation as measured by CD, PV, and TBARS values, and the lowest levels of myoglobin oxidation. At all incubating temperatures, the oxymyoglobin and lipid oxidation of all model systems tended to rise with the lengthening of the incubation duration. With the addition of 5% NPN, however, the lowest CD, PV, TBARS, oxymyoglobin oxidation, metmyoglobin formation, and protein carbonyl content were all observable, and the remarkable result was discovered during incubation at 4 °C. The results indicate that stingray NPN, especially at 5%, can be used to delay lipid and myoglobin oxidation, particularly at 4 °C. In order to prolong the shelf life of products with dark-fleshed fish and red meat, stingray NPN might be used as an alternative antioxidant to delay the oxidation of lipid and myoglobin during cold chain storage.

Effects of Primary Processing and Pre-Salting of Baltic Herring on Contribution of Digestive Proteases in Marinating Process

The low-technological quality of herring caught during the feeding season makes it impossible to achieve full ripeness of the meat in marinades. One solution may be to assist ripening using herring digestive tract proteases. Therefore, whole herring, headed herring and fillets were marinated for 2–14 days using the German (direct) and Danish (pre-salted) methods. The results showed that the mass of marinades from fillets was lower than from herring with intestines and correlated strongly with salt concentration in the Danish method, in contrast to the German method. Marinades from whole and headed herring had significantly higher trypsin, chymotrypsin, carboxypeptidase-A and cathepsin activities than marinated fillets. The herring marinated with viscera had 2–3 times higher non-protein nitrogen, peptide and amino acid fractions, as well as ripened 3 days faster than the marinated fillets. After 2 weeks of marinating, the fillets did not achieve full ripeness of the meat, unlike marinades made from whole and headed herring. The pre-salting stage in the Danish method significantly reduced cathepsin D activity by the tenth day of marinating, which was compensated by digestive proteases only in the case of whole or headed herring. The digestive proteases activity in the fillets was too low to achieve the same effect. Sensory evaluation of texture and hardness-TPA correlated strongly with several proteases in whole herring marinades, in contrast to a weak correlation with only one protease when marinating fillets. Marinating with intestines makes it possible to produce marinades faster, more efficiently and with higher sensory quality from herring of low-technological quality.

Prediction of fresh and ripened cheese yield using detailed milk composition and udder health indicators from individual Brown Swiss cows.

The composition of raw milk is of major importance for dairy products, especially fat, protein, and casein (CN) contents, which are used worldwide in breeding programs for dairy species because of their role in human nutrition and in determining cheese yield (%CY). The aim of the study was to develop formulas based on detailed milk composition to disentangle the role of each milk component on %CY traits. To this end, 1,271 individual milk samples (1.5 L/cow) from Brown Swiss cows were processed according to a laboratory model cheese-making procedure. Fresh %CY (%CYCURD), total solids and water retained in the fresh cheese (%CYSOLIDS and %CYWATER), and 60-days ripened cheese (%CYRIPENED) were the reference traits and were used as response variables. Training-testing linear regression modeling was performed: 80% of observations were randomly assigned to the training set, 20% to the validation set, and the procedure was repeated 10 times. Four groups of predictive equations were identified, in which different combinations of predictors were tested separately to predict %CY traits: (i) basic composition, i.e., fat, protein, and CN, tested individually and in combination; (ii) udder health indicators (UHI), i.e., fat + protein or CN + lactose and/or somatic cell score (SCS); (iii) detailed protein profile, i.e., fat + protein fractions [CN fractions, whey proteins, and nonprotein nitrogen (NPN) compounds]; (iv) detailed protein profile + UHI, i.e., fat + protein fractions + NPN compounds and/or UHI. Aside from the positive effect of fat, protein, and total casein on %CY, our results allowed us to disentangle the role of each casein fraction and whey protein, confirming the central role of β-CN and κ-CN, but also showing α-lactalbumin (α-LA) to have a favorable effect, and β-lactoglobulin (β-LG) a negative effect. Replacing protein or casein with individual milk protein and NPN fractions in the statistical models appreciably increased the validation accuracy of the equations. The cheese industry would benefit from an improvement, through genetic selection, of traits related to cheese yield and this study offers new insights into the quantification of the influence of milk components in composite selection indices with the aim of directly enhancing cheese production.

Use of Rapid Capillary Zone Electrophoresis to Determine Amino Acids Indicators of Herring Ripening during Salting.

Currently, herring fillets are salted with acetic acid to activate muscle proteases. This causes a change in the composition of free amino acids, compared to salting of whole fish with viscera proteases. Therefore, old indicators of the ripening dynamics of salted fish based on amino acids are not current. Determination of free amino acids can be performed by many methods, but most are labor intensive and expensive. Therefore, a capillary electrophoresis method without derivatization (CZE) was used to determine the actual ripening rates of salted herring fillets. A group of hydrophobic and basic amino acids were determined in trichloroacetic acid (TCA) extracts of meat and brine to develop 16 indicators. Statistical regression analysis of the indicators (R2adj, RMSE, cluster analysis) followed by principal component analysis (PCA) correlation analysis of the indicators vs sensory evaluation parameters of texture and TPA-hardness of salted fillet meat allowed the choice of the most precise indicators. The best indicator in meat was Phe/Tyr-height, which value increased during salting. A more precise indicator of ripening was His/Tyr-height in brine, which value decreased during salting. Sensory evaluation parameters of salted herring texture correlated strongly with TPA-hardness and traditional indicators such as non-protein nitrogen and protein hydrolysis product fraction content. However, the most precise indicators were those obtained from amino acids determined by the CZE method. Results obtained in this study may be suitable for fast monitoring of the salted herring ripening process in industry.

Preliminary Study of Extended Ripening Effects on Peptides Evolution and DPPH Radical Scavenging Activity in Mexican Goat Cheese

Cheese ripening causes intense proteolysis, particularly when the cheese contains starter cultures. Several studies have shown the presence of bioactive peptides in goat’s milk cheeses with antioxidant activity. Mexican goat cheeses’ peptide fractions were evaluated at different ripening stages. Additionally, they were correlated with their antioxidant activity. Proteolysis was measured in the acid-soluble nitrogen and non-protein nitrogen fractions using reverse-phase high-performance liquid chromatography. While the antioxidant activity in both nitrogenous fractions was determined using a 2,2-diphenyl-1-picrylhydrazyl solution. Analyzed cheeses showed peptides fraction in the retention time of 2.05, 18.36, and 50.11 min for acid-soluble fraction and non-protein protein nitrogen, and showed antioxidant activity from the first day of ripening to 73% discoloration in the DPPH solution at 55 ripening days. Obtained results suggested that ripened Mexican goat cheese had a DPPH radical scavenging activity related to peptides present originally in the milk or released by starter culture action during cheese ripening.

Comparative Studies on the Chemical Composition of Inland Saline Reared Litopenaeus vannamei

ABSTRACT A comparative study of chemical composition between the muscles of Litopenaeus vannamei reared in inland saline water (ISRV) and brackish water (BWRV) was taken up. Slightly higher water content, pH, nonprotein nitrogen fractions were observed in ISRV. Some amino acids like glutamic acid, aspartic acid, arginine, lysine and glycine contents were higher in BWRV. On the contrary, ISRV meat had higher hydroxyproline, alanine and leucine content. The polyunsaturated fatty acid content of BWRV and ISRV samples were 41.67% and 46.50%, respectively. Potassium was the dominant mineral in both BWRV and ISRV shrimp meats, i.e., 1011 and 836.3 mg/100 g of meat, respectively. The proportion of composition varied with both the shrimp sample. Though the composition was varied most of the amino acids, fatty acids and minerals were comparable to one another. Therefore, it can be concluded that the overall meat quality of ISRV shrimp is not affected.

Digestive Potential of Soybean Agro-Industry Byproducts.

Simple SummaryThis manuscript addresses the use of nutritional alternatives: that the addition of soybean hull levels affect protein and carbohydrate fractionation, with significant changes in rumen degradability; that most of the analyzed variables were affected linearly, so levels of additive inclusion resulted in the satisfactory growth of rumen microorganisms and synchronism between the protein and carbohydrate digestion rates; and that these had an important effect on the end products of fermentation and on animal production. This is significant because animals fed diets showing these characteristics can better express their animal performance. The results obtained in this study indicate that the addition of intermediate levels of soybean hulls close to 20–30% ensures better characteristics in the silage of Brachiaria decumbens.This study aimed to determine the protein and carbohydrate fractions as well as the in situ rumen degradability of Brachiaria decumbens silage (BDS) supplemented with soybean hulls. Five soybean hull inclusion levels were used: 0, 10, 20, 30, and 40% of the fresh matter of B. decumbens grass, distributed into a completely randomized design with five replications. The inclusion of soybean hulls caused a linear decrease (p < 0.001) in carbohydrate fractions A + B1 and a linear increase (p < 0.001) in carbohydrate fraction C. The percentage of non-protein nitrogen fraction increased linearly (p < 0.001), but the nitrogen fractions B1 + B2 and B3 presented a negative quadratic effect (p < 0.01) with soybean hull level and fraction C presented a linear decrease (p < 0.001). The dry matter (DM) degradability of soluble fraction (A) and the undigestible DM decreased linearly (p < 0.01) with the soybean hull level. The potentially degradable water-insoluble portion (DM fraction B) and degradability rate (c) of the DM fraction B increased linearly (p < 0.001) with soybean hull level. The crude protein (CP) fraction A presented a linear increase (p < 0.001) with soybean hull inclusion; however, soybean hull levels caused a linear decrease (p < 0.001) in the CP level of fraction B. The degradable insoluble fraction of NDF (D) of the silage increased linearly (p < 0.001) and the indigestible NDF fraction of the silage was linearly decreased with the soybean hull level (p < 0.001). The inclusion of intermediate levels (20–30%) of soybean hulls provided better protein and carbohydrate fractions and better quality of BDS.

Evaluation of seaweeds from marine waters in Northwestern Europe for application in animal nutrition

The increasing demand for animal protein by the growing world population intensifies the exploration of novel feed sources. This study evaluated the nutritional value of six intact seaweed species (i.e. the brown species Saccharina latissima, Laminaria digitata, and Ascophyllum nodossum, the red species Palmaria palmata, and Chondrus crispus and green species Ulva lactuca), collected from the coast of Ireland, Scotland and France as an ingredient for animal feed. The nutrient composition, in vitro digestibility, and in vitro gas production simulating rumen fermentation, were determined.The nutrient contents (g/kg dry matter), both between and within species, were highly variable, ranging from 45–248 for crude protein, 351–691 for non-starch polysaccharides, and 173–445 for ash. Overall, the brown seaweeds had the highest non-starch polysaccharides content, whereas samples of the red and green seaweeds had an amino acid content up to 265 g/kg dry matter. All samples had a substantial non-protein nitrogen fraction, varying from 0.12–0.29 of nitrogen. The fibre fractions of brown seaweeds showed different properties than land-based plants, as illustrated by a lower analysed neutral detergent fibre than acid detergent fibre content. The ileal organic matter and nitrogen digestibility, as well as the total tract organic matter digestibility (mean digestibility coefficients: 0.81, 0.89 and 0.88, respectively) were lower for all seaweeds compared to soybean meal (digestibility coefficients: 0.84, 0.98 and 0.97, respectively). S. latissima, L digitata, P. palmata and U. lactuca had a higher maximum gas production than alfalfa, but lower than sugar beet pulp. Based on the protein content and amino acid-pattern, intact P. palmata and U. lactuca would be a valuable protein source for farm animals, with the high non-starch polysaccharides and non-protein nitrogen contents and a low in vitro digestibility potentially limiting their use as a feed ingredient for monogastric species. The fermentability of L. digitata, S. latissima and P. palmata indicate that these intact seaweeds may have a higher nutritional value in ruminants. The high ash content in all seaweed species hampers the use of intact seaweed for both ruminants and monogastrics. Extraction of protein and other favourable components, while reducing the ash content, seems an important step towards seaweed inclusion in animal diets. Further identification and characterisation of seaweed polysaccharides is required to understand and improve the digestibility of seaweed fractions.

Effects of nutrition on main components of sheep milk

Abstract Nutrition markedly affects sheep milk composition and can be used to improve its suitability as food for humans. The effect of nutrition on sheep milk fat quality has been covered by many reviews. In contrast, nutrition and genetics interact on sheep milk protein. Milk true protein, whose mammary synthesis is under high genetic control, is much less affected than milk fat by nutritional management of the animals, whereas the non-protein nitrogen fraction of milk is largely affected by nutritional factors. Indeed, dietary-protein solubility and degradability and energy availability at rumen level can largely affect this fraction, especially milk urea. The latter is an excellent predictor of the protein nutritional status of sheep, based on the extent of nitrogen excretions through urine. Milk urea concentration is also an indicator of protein excesses and shortages associated with negative effects on the health, reproductive performance and immunocompetence of dairy ewes. Interestingly, milk urea concentration is inversely associated with somatic cell count (SCC) in sheep and cows. Nutritional errors can predispose the mammary gland to inflammations and, therefore, to a higher probability of mastitis occurrence, with a consequent increase in SCC in sheep milk. Moreover, specific dietary deficiencies in minerals (e.g. Se, Zn, Mn, and Fe) and vitamins (e.g. vitamin A, beta-carotene, and vitamin C) have also been associated with the health status of the mammary gland and SCC in milk. Recently, beneficial effects of dietary essential oils on SCC of sheep milk have been suggested. The nutrition as source of toxicants that could be transferred in sheep milk, will be updated and discussed. In conclusion, this review highlights that appropriate nutritional management can improve the composition of sheep milk, especially FA profile, and, to a certain extent, some milk compounds can be used to monitor the nutritional balance and health status of the animals.

Rumen undegradable protein (RUP) and its intestinal digestibility after steam flaking of cereal grains

While it is known that heat treatment of cereal grains generally improves the nutritional value for ruminants, simultaneous information on rumen degradability and intestinal digestibility of the rumen by-pass is scarce, especially for non-starch constituents. The effect of steam flaking at 90°C for 30 min on protein quality of maize, wheat, and barley was studied. In addition to proximal chemical analyses, protein rumen degradability was determined in vitro and intestinal digestibility of rumen undegraded protein was determined using the mobile bag method. No significant effects of steam flaking on chemical composition of cereal grains (crude protein, acid detergent fibre, neutral detergent fibre, and starch) were observed. The protein fractions that are relevant to rumen degradability were significantly influenced by the steam flaking: the non-protein nitrogen fraction (A) was reduced (P &amp;lt; 0.05) by 43–93% for all three cereal grains, whereas the fraction that represents true soluble protein (B1) was reduced (P &amp;lt; 0.05) for wheat grains (by 77%) and barley (by 93%). Although the difference was not significant, a decrease of 41% for B1 fraction was also observed for maize. On the other hand, steam flaking markedly increased buffer insoluble but neutral detergent soluble protein fraction (B2) by 15–25% for all three cereal grains, whereas effects on B3 fraction were not significant. Steam flaking was also associated with an increase of the rumen undegradable protein fraction (C) in the case of barley, from 6.6 to 11.1% of total N (P &amp;lt; 0.05) and wheat, from 5.2 to 8.4% of the total N (P &amp;lt; 0.05). Overall, the changes of the protein fractions led to a considerable increase of the rumen undegradable protein (RUP) for all steam-flaked cereal grains (P &amp;lt; 0.05). Steam flaking also increased (P &amp;lt; 0.05) intestinal digestibility of RUP of the cereal grains (by 3.6–34.8%), leading to a more efficient protein use in ruminants.

Biochemical Adaptation of Scots Pine (Pinus sylvestris L.) to Technogenic Pollution

We have investigated changes in the complex of biochemical parameters reflecting the disturbance of the homeostatic state and the activity of the adaptive reactions in Pinus sylvestris L. under the conditions of technogenic pollution. Disorders of the physiological state of trees growing under the effect of the excessive accumulation of pollutant elements result in changes in a number of parameters: a decrease in the ratio of protein and nonprotein nitrogen fractions in the needles by 52%; a decrease in the total phosphorus and its acid-soluble fraction by 40 and 63%, respectively; a decrease in carbon concentration by 31%; and a decrease in the amount of chlorophyll a, chlorophyll b, and carotenoids based on the weight of one needle by 23, 40, and 42%, respectively. The activation of protective reactions of pine is proven by an increase in the amount of ascorbic acid in needles by 48%; in the amount of water-soluble phenolic compounds by 29%; in the ratio of Chl. a/Chl. b by 35%; in the ratio of green pigments to yellow by 40%; and in the level of water- and alcohol-soluble proteins 40 and 30%, respectively. The highest activity of biochemical protection components was recorded in trees growing near the Shelekhovsky industrial center, the emissions of which contain a large amount of fluorides and polycyclic aromatic hydrocarbons (PAHs).

Characterization of goat milk from Lebanese Baladi breed and his suitability for setting up a ripened cheese using a selected starter culture

In this work the hygiene and quality parameters of goat milk from Baladi breeds were assess in order to evaluate his suitability for setting up a ripened cheese. Experimental cheese trials were performed on local Lebanese dairy farm using a selected culture starter. Evolution of physicochemical and microbiological features of experimental cheese during ripening were evaluated. Raw milk showed a good microbiological quality meeting the hygiene criteria given by European law on the hygiene of foodstuffs. Mesophilic lactobacilli were found to predominate during cheese fermentation while thermophilic cocci gradually grown and were preponderant during all ripening stage. Non-protein nitrogen and water soluble nitrogen fractions increased gradually over the ripening highlighting good casein primary proteolysis. The Free Fatty Acids (FFA) content increased through the ripening period reaching 7340mg/100g. Palmitic and oleic acids were the most representative long-chain FFAs at 210days whereas capric acid was found as a major short-chain FFA. Cheese ripened 90 days, revealed high score for the flavor and taste attributes and good globally acceptance.

Effect of selected divalent cations on protein mobilization in lentil (Lens culinaris) sprouts

The influence of calcium and magnesium on protein mobilization and non-protein nitrogen content in cotyledons of germinated lentil was studied. Elicitation of metabolism in sprouts modifies the rate of protein mobilization and causes a subsequent increase in the non-protein nitrogen fraction in lentil cotyledons. Application of MgCl2 proved to be the most beneficial, leading to the highest yield of non-protein nitrogen in cotyledons from 6-days-old lentil sprouts. Regardless of the type of elicitor, a decrease in the activity of proteolytic enzymes was observed in cotyledons from 3- and 4-day-old lentil sprouts. A significant correlation was found in sprouts elicited with MgCl 2 between the non-protein nitrogen content and activities of endo- and aminopeptidases. The information provided by this study allows us to design conditions for lentil sprouting which will result in an enhanced level of potentially bioaccessible non-protein nitrogen (free amino acids and peptides).

Antioxidant activity of Maillard reaction products derived from stingray (Himantura signifier) non-protein nitrogenous fraction and sugar model systems

This study aimed to evaluate the antioxidant activity of the Maillard reaction products (MRPs) derived from stingray non-protein nitrogenous (NPN) fraction and sugar (glucose, galactose and fructose) model systems. MRPs were prepared by heating the solution containing NPN (2 g nitrogen/100 ml) and sugar (2 g/100 ml) in 0.05 M sodium hydrogen carbonate buffer, pH 12 for 120 min at 100 °C. Reducing power and capacity to scavenge hydrogen peroxide (H2O2), hydroxyl radical (OH), 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) radical (ABTS+) and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) of all MRPs were greater than those of original NPN solution (P < 0.05). The MRPs derived from NPN–fructose tended to have the highest reducing capacity and free radical scavenging ability. However, the ferrous (Fe2+) chelating activity of all MRPs was lower than the original NPN solution (P < 0.05). Therefore, reducing power and scavenging activity toward free radicals and reactive oxygen species of NPN from stingray muscle can be improved significantly by reacting NPN with sugar particularly fructose via the Maillard reaction. However, the Maillard reaction seemed to show a negative impact on the Fe2+ chelating activity of stingray NPN.

Effect of vegetable coagulant, microbial coagulant and calf rennet on physicochemical, proteolysis, sensory and texture profiles of fresh goats cheese

In order to determine the technological suitability of vegetable coagulants for the manufacture of cheeses, two different aqueous extracts from cardoon (Cynara cardunculus subsp. flavescens and C. cardunculus subsp. cardunculus) and microbial coagulant (Mucor miehei) were compared with calf rennet. Optical sensors showed that the microbial coagulant had the highest clotting time (T max) whereas both rennet and vegetable coagulants had similar and lower milk clotting times. For most of the physicochemical (Colour CIELab, protein and fat) and textural (cohesiveness and springiness) parameters, no differences were observed between the different enzymes assayed. However, dry matter content, hardness, gumminess and chewiness showed significant differences, higher values being obtained in cheeses made with vegetable coagulants. As regards sensory properties, cheeses made with vegetable coagulants showed less firmness and whiteness but higher bitterness while microbial coagulant and calf rennet showed similar and higher values. No statistically significant differences were found in the soluble nitrogen or non-protein nitrogen fractions between the cheeses. The vegetable coagulants showed higher intensity bands in the Pre-αs-casein region, which was related to higher αs-casein proteolytic rates. The use of vegetable coagulants should enable manufacturers to produce fresh cheeses with new textural features, but to improve sensory profile, different technological strategies might be adopted.

Dry and moist heating-induced changes in protein molecular structure, protein subfraction, and nutrient profiles in soybeans

Heat processing has been used to improve protein utilization and availability of animal nutrition. However, to date, few studies exist on heat-induced protein molecular structure changes on a molecular basis. The aims of this study were to use molecular spectroscopy as a novel approach to determine heat-induced protein molecular structure changes affected by moist and dry heating and quantify protein molecular structures and nutritive value in the rumen and intestine in dairy cattle. In this study, soybean was used as a model for feed protein and was autoclaved at 120°C for 1h (moist heating) and dry heated at 120°C for 1h. The parameters assessed in this study included protein structure α-helix and β-sheet and their ratio, protein subfractions associated with protein degradation behaviors, intestinal protein availability, and energy values. The results show that heat treatments changed the protein molecular structure. Both dry and moist heating increased the amide I-to-amide II ratio. However, for the protein α-helix-to-β-sheet ratio, moist heating decreased but dry heating increased the ratio. Compared with dry heating, moist heating dramatically changed the chemical and nutrient profiles of soybean seed. It greatly decreased soluble crude protein, nonprotein nitrogen, and increased neutral detergent insoluble protein. Both dry and moist heating treatments did not alter digestible nutrients and energy values. Heating tended to decrease the nonprotein nitrogen fraction (soluble and rapidly degradable protein fraction) and true protein 1 fraction (fast-degradable protein fraction). Conversely, the true protein 3 fraction (slowly degradable fraction) significantly increased. The in situ rumen study showed that moist heating decreased protein rumen degradability and increased intestinal digestibility of rumen-undegradable protein. Compared with the raw soybeans, dry heating did not affect rumen degradability and intestinal digestibility. In conclusion, compared with dry heating, moist heating dramatically affected the nutrient profile, protein subfractions, rumen degradability, intestinal digestibility, and protein molecular structure (amide I-to-II ratio; α-helix-to-β-sheet ratio). The sensitivity of soybean seed to moist heating was much higher than that to dry heating in terms of the structure and nutrient profile changes.

Chemical composition and nutrient profile of low molecular weight fraction of bovine colostrum

Bovine colostrum collected within 12 h of parturition was de-fatted, de-caseinated, and ultrafiltered (UF) using a 5 kDa cut-off membrane; the resulting UF permeate was freeze dried to create a powder with possible use as a functional food ingredient. Samples representative of five lots of this powdered “colostrum low molecular weight fraction” (CLMWF) were analyzed for chemical composition and nutrient profile. The average contents of fat, moisture, and ash were 0.6%, 1.7%, and 8.3%, respectively. Carbohydrate analysis showed an average of 58.2% lactose monohydrate with no monosaccharides, other disaccharides, trioses, or tetroses detected. The total nitrogen content averaged 1.13%, with 74% of this in the non-protein nitrogen fraction, producing an apparent protein content of 1.9%. A significant mass fraction of the material (∼29%) remains to be characterized. The CLMWF powders contained significant quantities of calcium, magnesium, phosphorus, potassium and sodium, taurine, l-carnitine, thiamine, and riboflavin, and uridine, cytidine and guanosine based nucleos(t)ides.

Effect of starter culture on proteolytic changes during processing of fermented beef sausages

Abstract Fermented beef sausages inoculated with four different starter cultures (Pediococcus acidilactici, Lactobacillus curvatus, Lactobacillus sake, or Streptomyces griseus) were evaluated for proteolysis during process stages (prefermentation, fermentation, drying and heating). Increases (p ⩽ 0.05) in the nonprotein nitrogen (NPN) fraction were found at sequential stages of processing, while starter cultures had no major effects on NPN content. Concentrations of most free amino acids increased (p ⩽ 0.05) during fermentation and drying, and culture effects were found for differences among concentrations of some individual free amino acids. From SDS–PAGE analysis of sarcoplasmic and myofibrillar protein fractions after fermentation and drying, myosin heavy and light chains, actin and troponin were degraded during processing. However, starter culture effects were absent from SDS–PAGE protein patterns.

The possible role of human milk nucleotides as sleep inducers

Breast-milk contains a potent mixture of diverse components, such as the non-protein nitrogen fraction which includes nucleotides, whose variation in levels is evident throughout lactation. In addition, these substances play an important role in sleep homeostasis. In the present study, human milk samples were analyzed using a capillary electrophoresis system. The rhythmicity of each nucleotide was studied by cosinor analysis. It was found that the nucleotides 5′AMP, 5′GMP, 5′CMP, and 5′IMP have significant (P < 0.05) circadian rhythms, the acrophases of the first two being during the night, and of the latter two during the day. While 5′UMP did not show a clear circadian rhythm, there was an increase in its levels at night. In conclusion, the rise in nocturnal levels of 5′AMP, 5′GMP, and 5′UMP could be involved in inducing the 'hypnotic' action of breast-milk at night in the infant.