Soluble Nitrogen Content Research Articles

Fermented blend from sunflower seed press-cake and bovine sweet whey: Protein breakdown during in vitro gastrointestinal digestion

Sustainable food production implements circular economic system, valuing side streams and minimizing waste. This study was aimed to develop a new food by fermenting a blend of dehulled sunflower seed protein powder (SSPP) and reconstituted bovine sweet whey powder (RSWP). Blends were inoculated with Lactococcus lactis B12 alone or in association with Saccharomyces cerevisiae L12, and fermentation proceeded until reaching pH 4.8. After in vitro static gastrointestinal digestion, RSWP and SSPP proteins were highly proteolyzed and the soluble nitrogen content was 69–71% of total nitrogen. In digests, 42–75 unique peptides were identified, and most of them weighed 500–1000 Da. Free amino acids accounted for 202–228 mg/g protein in digests. Few bioactive peptides derived from RSWP were identified. These findings demonstrated strong degradability of RSWP and SSPP proteins during digestion and shed light on nutritional properties exploitable for food applications of the developed fermented blend.

Nutritional quality of tomato in response to different fertilization doses and conduction systems

The tomato, a rich source of essential nutrients such as vitamins A and C, potassium, and antioxidants, plays a crucial role in human nutrition, promoting health and preventing diseases. In Brazil, its production is vital, involving significant resources and labor. The correct nutritional management of the crop can improve the nutritional attributes of tomato fruits, therefore the correct use of fertilizers is of great importance due to the high need for phosphorus, nitrogen and potassium, throughout the crop cycle. Nutritional management is of great importance in tomato fields due to its high fertilizer requirements throughout the entire crop cycle. This study aimed to assess the effect of different fertilizer doses and management systems on the physicochemical characteristics of tomatoes. The experiment followed a factorial design with five fertilizer doses (A0: 0%; A1: 50%; A2: 100%; A3: 150%; A4: 200% of the recommended dose) and four conduction systems, with three replications. Productivity, lycopene content, total soluble solids (TSS), nitrogen, phosphorus, potassium, calcium and magnesium fruit contents were evaluated. The results showed that higher fertilizer doses increased lycopene levels, reaching 80 μg g-1 with 200% fertilization, while 0% provided 30 μg g-1. Total soluble solids above 4°Bx were observed at doses above 150%, regardless of planting density. Nitrogen content reached 26 mg·100 g-1f.m., favored by lower densities. Calcium was influenced by fertilizer doses, with higher concentrations at 150%. In conclusion, the application of 150% fertilizer dose improved the nutritional quality of tomatoes, and the 200% dose provided suitable levels of TSS and lycopene for processing.

Potassium Nutrition Induced Salinity Mitigation in Mungbean [Vigna radiata (L.) Wilczek] by Altering Biomass and Physio-Biochemical Processes

The present investigation was conducted to explore the role of potassium nutrition in improving biomass and physio-chemical alterations to reduce the adverse effects of salinity in mungbean. A sand-culture experiment was carried out under different salinity levels (0, 50, and 100 mM NaCl) with two levels of potassium (0 and 50 mM K2SO4) and two mungbean cultivars (NM-92 and Ramzan), and the alterations in mungbean biomass and metabolic activities were investigated. The results suggested that salinity significantly reduced the biomass, nitrate reductase activity (NRA), nitrite reductase activity (NiRA), total soluble proteins, chlorophyll a, chlorophyll b, total chlorophyll, nitrogen, potassium, calcium, magnesium, and phosphorous contents in both mungbean cultivars in comparison to the control. However, K2SO4 at 50 mM significantly improved all the parameters in both mungbean cultivars except for the sodium content. A significant increase in the total free amino acids, carotenoids, and sodium content in both mungbean cultivars was observed due to salt stress. Moreover, principal component analysis and heatmaps were developed individually for both mungbean cultivars to assess the variability and correlation among the studied attributes under all applied treatments. Under saline conditions, the mungbean ‘Ramzan’ showed more marked reductions in almost all the growth parameters as compared to ‘NM-92’. The results suggest that the application of K2SO4 ameliorates the adverse effects of salinity by regulating osmolyte production, NRA, and NiRA, thus promoting plant growth and productivity.

Assessment of functional UF- quinoa cheese properties

Quinoa flour at different ratios of 2, 4 and 6 % were used to produce UF- quinoa soft cheese treatments. Addition of quinoa improved sensory quality and other characters of quinoa soft cheese treatments than the control. For the chemical composition: TS, fat, TN, fiber and RSA values were increased. Soluble nitrogen and TVFA content were higher in UF- quinoa soft cheese treatments being the highest for that with quinoa 6 %. Viable counts of Bifidobacterium lactis and Lactobacillus casei were increased than the control. The good ability of quinoa protein to absorb water and fat help the texture forming to be smoother with no whey separation. UF- soft cheese with quinoa flour 2 and 4 % were the most palatable and preferable treatments comparing by the other treatments. All treatments stored for 28 days at (5 ± 2 °C). Three replicates were carried out for each treatment and the obtained data were statistically analyzed at p ≤ 0.05 when fresh and during storage.

Foliar spraying with a synthetic community of Bacillus increases the selenium content, quality, and contribution to phyllosphere microecology of pakchoi

Due to widespread selenium insufficiency worldwide, the human body's intake of selenium through foods has been a vital approach. Microorganisms have been widely used as a green and efficient tool for selenium biofortification of crops. However, most studies have focused on one type of PGPB, while the synergistic effects of multiple PGPBs have rarely been explored. In this study, a synthetic community was constructed by selenium absorption promotion strains, including Bacillus subtilis, Bacillus cereus, and Bacillus altitudinis, which were used instead of traditional single strain. The synthetic community was inoculated on leaves by foliar spraying under two exogenous selenomethionine treatments (10 mg L−1 and 20 mg L−1). Results showed that the synthetic community improved selenium absorption, growth, and quality of pakchoi largely. In contrast to the inoculation of Bacillus subtilis, Bacillus cereus, and Bacillus altitudinis respectively, the inoculation of the synthetic community increased the fresh weight (increased by 23.22 %, 14.55 % and 16.30 %), dry weight (increased by 13.91 %, 13.59 %, and 6.32 %) and selenium content (increased by 68.61 %, 54.37 %, and 12.46 %) in the treatments with the application of 10 mg L−1 selenium. The synthetic community inoculation enhanced the fresh weight (increased by 23.50 %, 26.35 %, and 15.63 %), dry weight (increased by 25.61 %, 20.72 %, and 15.77 %), selenium content (increased by 66.05 %, 90.20 %, and 38.90 %) in the treatments with the application of 20 mg L−1 selenium. Besides, the synthetic community also increased SPAD value, the contents of soluble protein, reducing sugar, vitamin C, and nitrogen content of pakchoi. And the nitrate content was significantly decreased. High-throughput sequencing of the 16S ribosomal RNA gene indicated that foliar spraying with synthetic community increased the relative abundance of Acinetobacter. This suggested that the composition of phyllosphere bacterial taxa was optimized by the synthetic community. This study demonstrated the potential of the synthetic community in the selenium biofortification of crops.

Optimizing irrigation and nitrogen management improves soil soluble nitrogen pools and reduces nitrate residues in a drip-fertigated apple orchard on the Loess Plateau

Appropriate water and nitrogen fertilizer management is crucial for achieving sustainable development in the apple industry. However, the soil nitrogen supply capacity and residual nitrate characteristics under drip fertigation remain poorly understood. Therefore, this study aims to (1) investigate the coupling effects of irrigation and nitrogen levels on the concentrations and distribution characteristics of soil soluble nitrogen fractions and residual soil nitrate; (2) explore the relationships between Christiansen uniformity coefficient (CU) of soil nitrate and apple yield, water productivity (WPc) and nitrogen use efficiency (nitrogen agronomic efficiency, AEn). The field experiment was conducted in a drip-fertigated apple orchard starting in 2017, which included two irrigation levels, 85% (W1) and 100% (W2) of field capacity (FC), and four nitrogen rates, 0 (N1), 120 (N2), 240 (N3) and 360 (N4) kg ha–1. The results showed that nitrogen inputs significantly increased soil soluble inorganic nitrogen and soluble organic nitrogen (SON) contents. However, the SON content significantly decreased when 360 kg N ha–1 was applied, particularly at W1. The maximum nitrate accumulation in the 0–3 m soil layer at N4 reached 2540.97 kg ha–1 in 2021, but the maximum value decreased to 1251.62 kg ha–1 in 2022 due to extreme rainfall. The average CU of residual nitrate across irrigation levels in the 0–3 m soil layer was highest at N3, with values of 0.68 and 0.57 in 2021 and 2022, respectively. High irrigation level increased the diffusion distances of nitrate both vertically and horizontally, resulting in a significant effect on CU. Apple yield and WPc first increased and then decreased with increasing nitrogen rates, while AEn consistently decreased, but they were all greater with a higher CU. The recommended combination of irrigation and nitrogen application was 85% FC and 240 kg N ha–1, which can achieve the dual goals of enhancing soil nitrogen supply capacity and minimizing environmental risks while improving orchard productivity.

From acidophilic to ornithogenic: microbial community dynamics in moss banks altered by gentoo penguins.

The study explores the indirect impact of climate change driven by gentoo's penguin colonization pressure on the microbial communities of moss banks formed by Tall moss turf subformation in central maritime Antarctica. Microbial communities and chemical composition of the differently affected moss banks (Unaffected, Impacted and Desolated) located on Galindez Island and Сape Tuxen on the mainland of Kyiv Peninsula were analyzed. The native microbiota of the moss banks' peat was analyzed for the first time, revealing a predominant presence of Acidobacteria (32.2 ± 14.4%), followed by Actinobacteria (15.1 ± 4.0%) and Alphaproteobacteria (9.7 ± 4.1%). Penguin colonization and subsequent desolation of moss banks resulted in an increase in peat pH (from 4.7 ± 0.05 to 7.2 ± 0.6) and elevated concentrations of soluble nitrogen (from 1.8 ± 0.4 to 46.9 ± 2.1 DIN, mg/kg) and soluble phosphorus compounds (from 3.6 ± 2.6 to 20.0 ± 1.8 DIP, mg/kg). The contrasting composition of peat and penguin feces led to the elimination of the initial peat microbiota, with an increase in Betaproteobacteria (from 1.3 ± 0.8% to 30.5 ± 23%) and Bacteroidota (from 5.5 ± 3.7% to 19.0 ± 3.7%) proportional to the intensity of penguins' impact, accompanied by a decrease in community diversity. Microbial taxa associated with birds' guts, such as Gottschalkia and Tissierella, emerged in Impacted and Desolated moss banks, along with bacteria likely benefiting from eutrophication. The changes in the functional capacity of the penguin-affected peat microbial communities were also detected. The nitrogen-cycling genes that regulate the conversion of urea into ammonia, nitrite oxide, and nitrate oxide (ureC, amoA, nirS, nosZ, nxrB) had elevated copy numbers in the affected peat. Desolated peat samples exhibit the highest nitrogen-cycle gene numbers, significantly differing from Unaffected peat (p < 0.05). The expansion of gentoo penguins induced by climate change led to the replacement of acidophilic microbiomes associated with moss banks, shaping a new microbial community influenced by penguin guano's chemical and microbial composition.

Nutraceutical potential of Mesembryanthemum forsskaolii Hochst. ex Bioss.: Insights into its nutritional composition, phytochemical contents, and antioxidant activity

Abstract Mesembryanthemum forsskaolii Hochst. ex Bioss is a resilient succulent plant in the Aizoaceae family. This plant has been recognized for its nutritional and metabolic benefits, but its potential remains underexplored. The aim of this research is to analyze the nutritional composition, phytochemical content, and antioxidant potential of M. forsskaolii. The protein content, total sugars, macro-, and micronutrients were estimated in seeds, leaves, and stems of the studied plant. To investigate the phytochemical profiles and antioxidant capacity, GC-MS analysis, determination of total phenolic, flavonoid, and tannin contents, ferric reducing antioxidant power (FRAP) and total antioxidant activity (TAC) tests, and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging assays were conducted. The soluble protein (147.55 mg g−1 DW), total protein (341.23 mg g−1 DW), total carbohydrate (0.258 mg mL−1), and nitrogen (26.152 mg g−1) contents of M. forsskaolii seeds were the highest. Phytochemical analysis revealed the presence of several compounds, such as β-sitosterol, phthalic acid, and phytol, which have potential antioxidative, anti-inflammatory, and antimicrobial properties. Seeds showed the greatest presence of phenols, flavonoids, and tannins, indicating high antioxidant activity in FRAP and TAC tests. The ABTS and DPPH scavenging assays showed that the antioxidant activity increased proportionally with concentration in all plant parts. However, seeds consistently demonstrated the greatest capacity. This study provides a detailed analysis on the dietary protein, carbohydrates, essential nutrients, and antioxidants that can be obtained from M. forsskaolii, highlighting its potential as a valuable source of nutrition and phytochemicals.

Nitrogen Metabolism during Anaerobic Fermentation of Actual Food Waste under Different pH Conditions

Acidogenic fermentation can convert food waste (FW) into small molecules of acids and alcohols, and the broth can be used as a carbon source of denitrification in wastewater treatment plants. However, the soluble nitrogen-containing substances generated in fermentation influence the quality of the carbon source, and microbial nitrogen transformation under different pH conditions has rarely been reported. In this study, four FW fermentation systems were operated continuously with a focus on nitrogen transformation, and metagenomic and metatranscriptomic analyses were used to reveal the metabolic pathways. The results showed that approximately 70% of nitrogen existed in solid organic matter, and the dissolution of solid proteins was limited at pH 4.0–5.0. The concentration of soluble nitrogen, encompassing both soluble organic nitrogen and ammonium, remained relatively stable across various pH conditions. However, high pH values promoted the conversion of soluble nitrogen-containing substances to ammonium, and its concentration increased by 122%, 180%, 202%, and 267% at pH 4.00, pH 4.27, pH 4.50, and pH 5.00. Lactobacillus played a crucial role in ammonium production via the arginine deiminase pathway at pH 4.0–4.5, and Prevotella was the key contributor with the assistance of glutamate dehydrogenase at pH 5.0. The findings provide insights into organic nitrogen transformation in acidogenic fermentation for optimizing FW treatment processes.

Physiological and Biochemical Analysis Revealing the Key Factors Influencing 2-Phenylethanol and Benzyl Alcohol Production in Crabapple Flowers.

Floral scent (FS) plays a crucial role in the ecological functions and industrial applications of plants. However, the physiological and metabolic mechanisms underlying FS formation remain inadequately explored. Our investigation focused on elucidating the differential formation mechanisms of 2-phenylethanol (2-PE) and benzyl alcohol (BA) by examining seven related enzyme concentrations and the content of soluble sugar, soluble proteins, carbon (C) and nitrogen (N), as well as the C/N ratio. The findings revealed that the peak content of 2-PE in M. 'Praire Rose' and BA in M. 'Lollipop' occurred during the end flowering stage (S4) and flowering stage (S3) periods, respectively. The enzyme concentration change trends of phenylpyruvate decarboxylase (PDL), phenylacetaldehyde reductase (PAR), soluble protein, C, N, and C/N ratio changes during the S3-S4 period in M. 'Praire Rose' and M. 'Lollipop' were entirely opposite. Correlation and PCA analysis demonstrated that the content of CYP79D73 (a P450) and N, and the C/N ratio were key factors in 2-PE production in M. 'Praire Rose'. The production of BA in M. 'Lollipop' was more influenced by the content of phenylacetaldehyde synthase (PAAS), CYP79D73, and soluble sugar. As CYP79D73 exits oppositely in correlation to 2-PE (M. 'Praire Rose') and BA (M. 'Lollipop'), it is hypothesized that CYP79D73 was postulated as the primary factor contributing to the observed differences of 2-PE (M. 'Praire Rose') and BA (M. 'Lollipop') formation. These results carry significant implications for crabapple aromatic flower breeding and the essential oil industry etc.

Evaluation of AnnAGNPS Wetland Nitrogen Removal Component on Farmed Prairie Potholes

Highlights AnnAGNPS offers a wetland module (AgWET) to simulate farmed prairie potholes soluble nitrogen dynamics. Three key parameters of the AgWET nitrogen removal components show high and very high Relative Sensitivity (Sr ). AnnAGNPS tends to underestimate the soluble nitrogen concentration at the beginning of the cropping season. Abstract. Farmed prairie potholes are common in northern Iowa and have been considered an impediment to agricultural development. Potholes have distinctive wetland characteristics where they might contain a high concentration of soluble nitrogen coming from agricultural upland runoff. With sub-surface drainage underneath them, providing short circuit nutrient transport downstream, Iowa poses a significant threat to nitrogen export to the Gulf of Mexico. Watershed models, such as AnnAGNPS, developed a wetland module allowing users to find the possible BMPs to accomplish nutrient reduction targets. Previous research indicates that AnnAGNPS may be used to mimic inundation depth fluctuations in potholes with moderate success. However, there has been little research on the wetland nitrogen removal components of the model. This study aims to evaluate the AnnAGNPS wetland module's performance in simulating the soluble nitrogen concentration in three farmed prairie potholes by comparing the simulation output with the observed data. The sensitivity analysis of the three key parameters of the model shows high and very high levels of sensitivity, with the temperature coefficient's relative sensitivity ranging from -6.7 to 8.6. Attempts in parameterization on the three targeted parameters indicated that the model poorly simulated the soluble nitrogen concentration. The comparison between observed and simulated data shows that the model fails to predict the high concentration of soluble nitrogen in the early cropping season. This conclusion is consistent with earlier research indicating that AnnAGNPS tends to underestimate the nitrogen concentration during the cropping season. Keywords: AnnAGNPS wetland module, Farmed prairie pothole, Soluble nitrogen concentration.

Proteolytic Changes During Ripening Of Kučki Cheese

Summary Production of various traditional dairy products, particularly cheese, has a long history in Montenegro. White-brined cheeses are the most well-known. One of them is Kučki cheese, with distinct flavor and higher level of proteolysis. The aim of this research was to analyze the proteolysis process during ripening of Kučki cheese. The cheese is produced using traditional technology. FTIR Spectrophotometry was used to calculate the amount of total protein in cheese (IDF141C: 2000). The degree of proteolysis was determined by SDS PAGE (Laemmli, 1970). The cheese was examined for their water-soluble nitrogen (WSN) content using Kuchroo and Fox’s method from 1982, as well as their 5% phosphotungstic acid soluble nitrogen (PTAN) content using Stadhouser’s method from 1960. The results were expressed as percentages of WSN and PTAN of the total nitrogen matter (WSN/TN and PTAN/TN), as well as PTAN as a percentage of WSN (PTAN/WSN). All analyses were done on 10th, 20th and 30th day of cheese ripening. Four samples of cheese were analyzed for each ripening period. The content of proteins increased during the ripening period. The parameters that determine the process of proteolysis increased during the first 30 days of ripening. The WSN/TN ranged from 13.33 to 44.32%. Also, PTAN/WSN varied from 3.79 to 21.57%. The initial results show that uneven ripening conditions have a direct impact on how proteolytic changes develop throughout ripening. Due to the absence of established cheese-making procedures, Kučki cheese has a considerable degree of heterogeneity in their protein content and proteolysis parameters. However, it is not possible to strictly define the optimal values of the degree of ripening for Kučki cheese. In order to reach certain conclusions, it is necessary to carry out further studies focusing on analyzing a larger number of samples.

Linkages of soil CO2 emission with plant functional traits in young subtropical plantations.

Soil respiration is a key process in forest biogeochemical cycling. Exploring the relationship between plant functional traits and soil respiration can help understand the effects of tree species conversion on soil carbon cycling. In this study, we selected 15 common subtropical tree species planted in the logging site of second-generation Chinese fir forest to measure soil CO2 emission fluxes, soil physicochemical properties, leaf and root functional traits of each species, and explored the effects of plant functional traits on soil respiration. The results showed that the annual flux of soil CO2 emissions varied from 7.93 to 22.52 Mg CO2·hm-2, with the highest value under Castanopsis carlesii (22.52 Mg CO2·hm-2) and the lowest value under Taxus wallichiana (7.93 Mg CO2·hm-2). Results of stepwise regression analysis showed that the annual flux of soil CO2 emission decreased with the increases of leaf nitrogen content and fine root diameter, and increased with increasing leaf non-structural carbohydrate. In the structural equation model, leaf non-structural carbohydrate had a direct and significant positive effect on soil CO2 emission fluxes, while leaf nitrogen content and fine root diameter had a direct negative effect by decreasing soil pH and soluble organic nitrogen content. Plantations of different tree species would affect soil CO2 emission directly by changing functional traits related to water and nutrient acquisition or indirectly through soil properties. When creating plantations, we should select tree species based on the relationship between plant functional traits and ecosystem functions, with a view to improving forest productivity and soil carbon sequestration potential.

Metabolites, flavor profiles and ripening characteristics of Monascus-ripened cheese enhanced by Ligilactobacillus salivarius AR809 as adjunct culture

Adjunct cultures strongly determined the distinguishing sensorial and nutritional characteristics of cheeses. Metabolites, flavor profiles and ripening characteristics of Monascus-ripened cheese enhanced by the co-fermentation of Ligilactobacillus salivarius AR809 were investigated. The AR809 significantly increased the contents of soluble nitrogen, small peptides (<1200 Da), free amino acids, and casein degradation degree in the resulting cheese. Furthermore, AR809 significantly promoted the formation of methyl ketones during cheese maturation. Based on untargeted metabolomics analysis, metabolites related to fatty acids metabolism and lysine degradation were highly enriched in Monascus-rich region of cheese. AR809 was primarily engaged in amino acid metabolism, promoting the synthesis of amino acids and dipeptide. L. salivarius and Monascus co-fermentation produced more beneficial bioactive metabolites involved in amino acids and lipid metabolisms than Monascus used alone in cheese ripening. Therefore, as adjunct culture, L. salivarius AR809 exhibited tremendous potential in improving nutrition and flavor quality during cheese ripening.

Responses of wheat nitrogen uptake and utilization, rhizosphere bacterial composition and nitrogen-cycling functional genes to nitrogen application rate, planting density and their interactions

The nitrogen application rate and planting density affect soil physiochemical properties, plant physiological characteristics, and soil bacterial community composition. In this study, a two-factor randomized block design was adopted with two planting density levels (high density, HD and low density, LD), and three nitrogen application rate levels (no nitrogen application, N0, low nitrogen application, LN and high nitrogen application, HN). The results showed that the highest yield was produced by LDHN and HDLN, while HDLN had the highest nitrogen use efficiency. Root dry weight was highest in HDHN, followed by HDLN, LDHN and LDLN, while the root nitrogen content was highest in LDHN and HDLN. In the 0–20 cm soil, LDLN had the highest pH and lowest nitrate nitrogen content, HDHN had the lowest pH, and HDLN had the highest content of soluble organic nitrogen and free amino acids. In addition, compared to LDHN, the bacterial community in HDLN and LDLN had higher α diversity and a higher relative abundance of functional genes involved in nitrate reduction. However, HDHN was the opposite. Additionally, correlation analysis also found that the abundance of some bacterial modules was significantly correlated with wheat nitrogen partial factor productivity. Overall, nitrogen application rates and planting density, through changing the physicochemical properties of rhizosphere soil, bacterial composition and function, and wheat root physiological properties, changed the nitrogen utilization and yield of wheat.

Protein digestibility of textured wheat protein (TWP)-based meat analogs: (II) Effects of sodium tripolyphosphate

In this study, the effects of adding sodium tripolyphosphate during the extrusion of textured wheat protein (TWP)-based meat analogs were investigated. Five TWPs (TWP-C0, TWP-C0.10, TWP-C0.25, TWP-C0.50, and TWP-C0.75) were prepared with sodium tripolyphosphate concentrations of 0%, 0.10%, 0.25%, 0.50%, and 0.75%, respectively. The fibrous structure of TWPs was analyzed by determining their textural properties, degree of texturization, microstructure, and protein bonds. When the concentration of sodium tripolyphosphate increased from 0% to 0.75%, the fibers in TWPs became more regular and finer with smaller pores, the degree of texturization increased from 2.10 ± 0.09 to 2.73 ± 0.07, and the proportions of solubilized protein from the breaking of hydrophobic bonds and disulfide bonds increased from 2.06 ± 0.14% and 1.38 ± 0.11% to 3.42 ± 0.12% and 1.74 ± 0.05%, respectively. The results of particle size, soluble nitrogen content, and free amino acids of samples during digestion indicated that the disintegration rate and protein digestibility of TWPs increased with the increase in the concentration of sodium tripolyphosphate. After gastrointestinal digestion, the total free amino acids released in TWP-C0, TWP-C0.10, TWP-C0.25, TWP-C0.50, and TWP-C0.75 were 391.5 ± 2.2, 403.9 ± 1.5, 430.0 ± 3.6, 473.8 ± 2.9 and 485.3 ± 5.73 mg/10 g digesta, respectively. Sodium tripolyphosphate may improve the protein digestibility of TWPs by forming a finer fibrous structure with a more unfolded protein structure and more hydrophobic groups being exposed to enzymes.

Mutual feeding mechanism of carbon, nitrogen and enzyme activity in Northeast China black soil under snow cover change

Projected future changes in snow cover patterns associated with global warming in cold zone ecosystems could affect soil biochemical cycling. However, the effects of snow cover changes on soil available carbon, nitrogen and enzyme activities and their potential response mechanisms have not been clarified. Therefore, from November 2021 to April 2022, this study conducted a snow depth manipulation test of four treatments in the northeast black soil region, and divided the test period into five stages to measure soil temperature and humidity, microbial biomass, enzyme activity, and available carbon and nitrogen. The results showed that the decrease of snow cover increased the freeze-thaw cycle frequency and freezing temperature of soil, but decreased the soil water content. Soil total organic carbon and inorganic nitrogen contents were increased in early and deep snow periods, while snow treatment was on the contrary. Due to the release of soluble nutrients caused by frequent freeze-thaw processes, Soil soluble organic carbon and Soil soluble organic nitrogen contents increased with the decrease of snow depth in deep snow period, snowmelt period and subsequent early crop growth period. Snow treatment increased soil microbial carbon and nitrogen content in early winter and early spring because snow provided heat insulation. Soil enzyme activities increased with the increase of snow cover. Compared with the control, soil urease activities and sucrase activities increased by 18.5 % and 11.5 % under snow treatment, and decreased by 23.2 % and 10.8 % under snow reduction treatment. In addition, soil soluble organic matter was a controlling factor for soil microbial biomass and enzyme activity throughout winter. The direct effect of soil soluble organic carbon and nitrogen on soil enzymes will make soil enzymes participate in the cyclic transformation process of available carbon, thus forming a closed loop of mutual feedback between soil available carbon and nitrogen and enzymes. These results demonstrated that the changes of snow cover in the future will have certain effects on soil carbon and nitrogen cycles and enzyme activities and hence biogeochemical cycling in terrestrial system of earth.

Determinação de parâmetros do queijo minas artesanal associados com as regiões de origem em Minas Gerais, Brasil

ABSTRACT Artisanal cheese production involves a centuries-old tradition in the state of Minas Gerais in Brazil, playing an important historical and social role. The aim of this study was to evaluate the characteristics of artisanal Minas cheeses from seven regions certified for their production in relation to their physical-chemical and centesimal composition to identify parameters that are useful to differentiate them. There were differences among the cheeses from different regions for the soluble nitrogen variables, extension and depth of ripening indexes, ash, oxidation, fat and pH. The highest values for the ripening length and depth index were observed in the Cerrado region. The cheeses from the Canastra region were different due to the higher moisture content, and the cheeses from Campo das Vertentes presented higher pH and nitrogen compound values. Despite the similarities among cheeses in each region, they had dispersed positions in the principal components analysis. There are differences in the physicochemical and centesimal composition among the artisanal Minas cheeses from the distinct regions in Minas Gerais, and the analyzed parameters can be used to differentiate them. The contents of ash, fat, oxidation index, soluble nitrogen and pH were the parameters that were associated with greater differences in cheeses.

Products and Properties of Components from Heat-Denatured Peanut Meal Following Solid-State Fermentation by Aspergillus oryzae and Saccharomyces cerevisiae

In heat-denatured peanut meal (HDPM), proteins are denatured and polysaccharides are degraded and browned. It can only be used as feed or fertilizer, and not using it as such is a waste of resources. To achieve high-value HDPM use, solid-state fermentation by Aspergillus oryzae and Saccharomyces cerevisiae was investigated. Conditions were optimized by response surface methodology and high-value antioxidant peptides (APs), nonstarch polysaccharides (NSPs), and fermentation products of heat-denatured peanut meal (FHDPM) were obtained. Optimal culture conditions were strain ratio 6:5, inoculation volume 2 mL, and fermentation for 42 h at 35 °C. Under optimal conditions, the theoretical soluble nitrogen concentration, 1,1-Diphenyl-2-picrylhydrazyl radical scavenging rate, hydroxyl free radical scavenging rate, and NSP yield reached 44.78 mg/mL, 62.44%, 94.95%, and 3.73%, respectively; however, their experimental values were 46.80 ± 1.23 mg/mL, 72.18 ± 0.78%, 96.79 ± 0.55%, and 4.42 ± 0.21%, respectively. NSPs, Aps, and FHDPM exhibited four higher classes and eight types of antioxidant activities. Moreover, levels of amino acids and trace elements, and physicochemical properties including emulsion activity index, emulsion stability index, foam capacity, foam stability, water holding capacity, and oil absorption capacity were enhanced by fermentation. The results indicate that APs and NSPs could serve as promising natural antioxidants in the food industry, and FHDPM could be used as a new type of high-value nutritional product in the feed industry. The findings provide new insight for comprehensive processing and utilization of HDPM.

Microbial community-based production of single cell protein from soybean-processing wastewater of variable chemical composition

The use of food-processing wastewaters to produce microbial biomass-derived single cell protein (SCP) is a sustainable way to meet the global food demand. Microbial community-based approaches to SCP production have the potential benefits of lower costs and greater resource recovery compared to pure cultures, yet they have received scarce attention. Here, SCP production from soybean-processing wastewaters using their existent microbial communities was evaluated. Six sequencing batch reactors of 4.5-L working volume were operated at 30 °C for 34 d in cycles consisting of 3-h anaerobic and 9-h aerobic phases. Four reactors received no microbial inoculum and the remaining two were amended with 1.5 L of a mixed culture from a prior SCP production cycle. Reactors produced more SCP when fed with wastewaters of higher soluble total Kjeldahl nitrogen (sTKN) content. The protein yield in biomass ranged from 0.53 to 3.13 g protein/g sTKN, with a maximum protein content of 50 %. The average removal of soluble chemical oxygen demand (sCOD) and soluble total nitrogen (sTN) was 92 % and 73 %, respectively. Distinct microbial genera were enriched in all six bioreactors, with Azospirillum, Rhodobacter, Lactococcus, and Novosphingobium dominating. The study showed that constituents in soybean wastewater can be converted to SCP and demonstrated the effect of variable influent wastewater composition on SCP production.