Detoxification of corn stalk pretreated with calcium hydroxide for true protein accumulation

Alkaline pretreatment is essential in lignin degradation, but the inhibitors produced in this process affect microbial growth. To overcome the impacts of the phenolic compounds, detoxification was applied to corn stalk pretreated with calcium hydroxide.The results showed that ferulic acid degradation rate can reach 85.11% by laccase at the optimal conditions. Phanerochaete chrysosporium degraded most vanillin (77.19%) and p-hydroxybenzaldehyde (63.82%) but the degradation of ferulic acid (15.34%) was relatively weak. Laccase combined with Phanerochaete chrysosporium detoxified most of the phenolic compounds including 2- methoxy-4-vinylphenol (88.46%) and salicylic acid (58.13%) that hardly decompose alone after calcium hydroxide pretreatment in this study. These results inferred that Phanerochaete chrysosporium might generate some substance during the spore germination and growth period which may cooperate with laccase to decompose the phenolic compounds. After the fermentation of detoxified corn stalk by Neurospora crassa, the true protein content was increased by 2.73 times, and 21.17% lignin was degraded.

Fractionation of carbohydrates and proteins and in vitro rumen kinetics of corn silage under various storage durations

The experiment evaluated the effects on the chemical composition (fermentation, kinetic parameters, and protein and carbohydrate fractions) of corn silage after various storage durations (45, 90, 180, and 360 days). Experimental mini silos of the corn plants were made and opened after various storage periods. The experimental design was completely randomized with four treatments and four replications per treatment. Variables such as pH, lactic acid and acetic acid showed a quadratic effect, whereas effluent and gas losses increased linearly with prolonged storage. Proteolysis was observed with an increase in storage, resulting in a rise in ammonia-N, soluble N, and non-protein N concentration and reduction in true protein. The soluble carbohydrate fractions were reduced, and digestible and indigestible fibre were increased. For the kinetic degradation parameters of the silages obtained through in vitro gas methodology, the highest fermentation rate occurred in the first 12 hours of incubation, and the highest volume of gas produced within 96 hours was obtained for silages with shorter storage (45 days). The increase in storage resulted in greater losses and lower ruminal degradability in vitro, causing a decrease in protein quality and nutritional value.

Brief Research Report: Estimation of the Protein Digestibility-Corrected Amino Acid Score of Defatted Walnuts

Introduction: Walnuts are considered a good source of essential fatty acids, which is unique among tree nuts. Walnuts are also composed of about 10–15% protein, but the quality of this protein has not been evaluated. Pistachios and almonds have been evaluated for their protein content using a protein digestibility-corrected amino acid score (PDCAAS), but it is unclear how the quality of protein in walnuts relates to that in other commonly consumed tree nuts. The objective of this study was to substantiate the protein quality of walnuts by determining their PDCAAS.Methods: A small, 10-day dietary intervention trial was conducted using male Sprague-Dawley rats (n = 8, 4 per group) with two diets: a nitrogen-free diet and a diet containing protein exclusively from defatted walnuts. Feed intake and fecal output of nitrogen were measured to estimate the true protein digestibility, and the amino acid compositions of walnuts compared to child and adult populations were used to calculate amino acid scores (AAS) and PDCAAS.Results: The true protein digestibility score of raw walnuts was calculated to be 86.22%. Raw walnuts contained 15.6 g protein/g walnut with AAS of 0.45 and 0.63 for children aged 6 months to 3 years and 3–10 years, respectively. For each population, a PDCAAS of 39 and 46% was calculated, respectively, using a protein conversion constant of 5.30. Using a protein constant of 6.25, a PDCAAS of 39% (6 months - 3 years) or 46% (3-10 years) was calculated.Conclusions: This is the first known assessment of the PDCAAS of walnuts. Like almonds, they appear to have a low-to-moderate score, indicating they are not a quality source of protein.

Optimization of Spiral-Wound Microfiltration Process Parameters for the Production of Micellar Casein Concentrate

A systematic selection of different transmembrane pressures (TMP) and levels of diafiltration (DF) was studied to optimize these critical process parameters during the manufacturing of micellar casein concentrate (MCC) using spiral-wound polymeric membrane filtration. Three TMPs (34.5, 62.1, and 103.4 kPa) and four DF levels (0, 70, 100, and 150%) were applied in the study. The effect of the TMP and DF level on flux rates, serum protein (SP) removal, the casein-to-total-protein ratio, the casein-to-true-protein ratio, and the rejection of casein and SP were evaluated. At all transmembrane pressures, the overall flux increased with increases in the DF level. The impact of DF on the overall flux was more pronounced at lower pressures than at higher pressures. With controlled DF, the instantaneous flux was maintained within 80% of the initial flux for the entire process run. The combination of 34.5 kPa and a DF level of 150% resulted in 81.45% SP removal, and a casein-to-true-protein ratio of 0.96. SP removal data from the lab-scale experiments were fitted into a mathematical model using DF levels and the square of TMPs as factors. The model developed in this study could predict SP removal within 90–95% of actual SP removal achieved from the pilot plant experiments.

Effects of Vanillic Acid on Dynamic Fermentation Parameter, Nitrogen Distribution, Bacterial Community, and Enzymatic Hydrolysis of Stylo Silage

Vanillic acid (VA) is a phenolic acid derivative commonly found in plants and foods, with a pleasant creamy odor and pharmacologic activities, which is hypothesized to help improve silage fermentation. The silage profile of stylo silage ensiled with addition of VA was evaluated. The results showed that VA addition resulted in the decrease of pH value (5.22 vs. 4.33), dry matter loss (5.37 vs. 2.51% DM), and ammonia-N proportion (14.57 vs. 1.51% CP) of stylo silage as well as the increase of lactic acid concentration (0.51 vs. 1.17% DM), true protein proportion (51.18 vs. 58.47% CP), and saccharification yield (113.64 vs. 126.40 mg/g DM). Meanwhile, bacterial community of stylo silage was altered, where the relative abundance of Enterobacter, Clostridium, and Kosakonia decreased and that of Commensalibacter and Methylobacterium increased. In conclusion, it is suggested that VA could be used as a novel silage additive to improve silage fermentation and nutrient preservation of stylo silage.

Improving the Nutritional Values of Cassava Pulp Through Supplementation of Selected Leaves Meal and Fermentation with Chrysonilia Crassa

This study evaluated the impact of fermentation with Chrysonilia crassa on nutritional composition and antioxidative activity of the mixture of cassava pulp and selected leaves meal. Cassava pulp (60 g) was mixed thoroughly with 35 g leaves meal of either cassava, M. Oleifera, or L. leucocephala, and inoculated with Chrysonilia crassa starter (5 g). The mixture was aerobically incubated for 3 days at room temperature and analyzed for the proximate composition, gross energy, true protein, antioxidant activity, and amino acid content. The fermented products showed higher crude protein, ether extract, ash, and gross energy but lower fibre content than unfermented cassava pulp. Both leaves meal supplementation and fermentation increased the true protein content of cassava pulp. Superior antioxidant activities and higher amino acids were observed in the fermented products than raw cassava pulp. In conclusion, supplementation of leaves meal in conjunction with Chrysonilia crassa-fermentation improved the nutritional values and antioxidant potential of cassava pulp.

Optimization of Spiral-wound Microfiltration Process for Production of Micellar Casein Concentrate

Micellar Casein Concentrate (MCC) is manufactured from microfiltration (MF) of skim milk utilizing ceramic or polymeric membrane filtration. While ceramic filtration has higher efficiency, use of polymeric is cost effective and the process is familiar to several US dairy processors. The aim of the present study was to develop an optimized membrane filtration process to produce MCC using spiral wound polymeric membrane filtration (SW MF) system by systematic selection of transmembrane pressure (TMP) and level of diafiltration (DF). Using skim milk as feed material, preliminary lab-scale MF experiments were conducted using 0.5 µm polyvinylidene fluoride (PVDF) membrane. Three TMP (34.5, 62.1, and 103.4 kPa) and three levels of DF (70, 100, and 150%) along with a process without DF as control were used in the study. Effect of TMP and effectiveness of DF on flux rates, SP removal, casein to total protein (CN/TKN) ratio, casein to true protein (CN/TP) ratio, rejection of casein (rej CN) and SP (rej SP) were evaluated. At all TMP values used in the study, the overall flux (O Flux) increased with the level of DF. Highest O Flux of 30.77 liter per meter square per hour (LMH) was obtained with 34.5 kPa pressure and 150% DF. The impact of DF was more pronounced at lower pressures than at the higher pressures used in the study. With controlled DF, instantaneous flux was maintained within 80% of initial flux for the entire process run. For all the experiments, casein has a rejection of 0.97 to 1.0, while serum protein has the lowest rejection of 0.10 at 34.5 kPa pressure and 150% DF level. Use of 34.5 kPa and DF level of 150 % contributed to 81.45% SP removal, and casein to true protein ratio of 0.96. SP removal data from the lab-scale experiments were fitted into a mathematical model using DF and square of TMP as factors. The model predicts SP removal within 90-95% of actual SP removal got from the pilot plant experiments.

Optimization of Medium for Bioconversion Extruded Apple Pomace into Microbial Protein

The medium compositions such as carbon and nitrogen sources, moisture content and inorganic salt affected the microbial protein (MP) production. Imbalance of carbon-nitrogen ratio in apple pomace (AP) limited the microbial utilization. Hence, those conditions must be optimized to achieve maximum MP. In this work, AP was pretreated by extrusion technology to obtain extruded apple pomace (EAP). Subsequently, the medium compositions were optimized using Plackett-Burman design (PBD) and Box-Behnken design (BBD). PBD determined four significant factors (bran, glucose, packing quantity (PQ), water to material ratio (W/M)) out of the eight variables. The BBD results showed that optimal true protein content (10.42%), effective viable count (1.94×109 CFU/g) and crude protein content (18.73%) were achieved at bran 16.22%, glucose 8.09%, PQ 9.88 g and W/M 1.56. Compared with AP, the true protein and crude protein content of optimal fermented EAP (FEAP) were increased by 152% and 216%, respectively. According to fluorescence microscopy, the cellulose of AP was little effected by extrusion technology while was mostly degraded by mixed strains (Aspergillus niger, Candida utilis, Geotrichum candidum and Lactic acid bacteria). Combination of extrusion and fermentation, the medium compositions were optimized to promote the bioconversion of AP into MP feed.

Factors Influencing Breast Milk Fat Loss during Administration in the Neonatal Intensive Care Unit

The objective of this study was to investigate factors influencing fat loss during tube feeding of breast milk to preterm infants. An experimental study with 81 feeding simulations was performed, with nine continuous infusions in each of six modalities: Horizontal Higher, Horizontal Matched, Horizontal Lower, Tilted Higher, Tilted Matched, and Tilted Lower, and for comparison, 27 bolus feedings: nine flushed with air, nine with water, and nine that were not flushed, done at matched height. Each simulation utilized 16 mL of breast milk given over four hours. Continuous infusions were given with a flow rate of 4 mL/h. Bolus was given as 8 mL over the course of 15–20 min every other hour. Analysis for fat, true protein, carbohydrate, total solids, and energy was performed before and after each simulation. The percent of macronutrient loss was compared between all simulations. Continuous infusion resulted in an average fat loss of 40%. Bolus feedings resulted in an average fat loss of 11% (p ≤ 0.001). Considerable fat loss is seen during continuous tube feeding. Neither height in relation to the infant nor tilting of the pump reduce fat loss. To limit fat loss, the bolus feeding method should be utilized.