Higher Lactic Acid Content Research Articles

Lemon juice and apple juice used as source of citrate and malate, respectively, enhance the formation of buttery aroma compounds and/or organic acids during Type 2 and Type 3 sourdough productions performed with Companilactobacillus crustorum LMG 23699

Extra ingredients are often used in traditional sourdough production recipes by artisan bakeries. These ingredients may be the source of microorganisms or stimulate the growth and/or the metabolic activities of the microorganisms added to or naturally present in the flour-water mixture. The present study examined the influence of the addition of lemon juice or apple juice as source of citrate or malate, respectively, on the growth and activity of the citrate- and malate-positive Companilactobacillus crustorum LMG 23699 strain (formerly known as Lactobacillus crustorum LMG 23699), used to initiate firm (dough yield of 200) wheat sourdough productions, and on the flavour of the baked goods produced. Three fermentation strategies were applied, namely one-step long fermentation sourdough production processes with the addition of juice at the start (Type 2) and backslopped fermentations with the addition of juice either only at the start of the sourdough productions or at the start of the sourdough productions and at the beginning of each subsequent refreshment step during the whole backslopping process (both Type 3). It turned out that the starter culture strain used prevailed during all sourdough productions performed. Yeasts were particularly present in Type 3 sourdough productions, although lemon juice retarded their growth. Due to high yeast activity, high concentrations of ethanol and glycerol were produced toward the end of the sourdough productions. Addition of lemon juice stimulated the production of lactic acid, acetic acid, and the buttery flavour compounds acetoin and diacetyl, because of citrate conversion, during the Type 2 and Type 3 sourdough productions. In Type 3 sourdough productions, these compounds were found in higher concentrations only when lemon juice was added at each backslopping step. Alternatively, the addition of apple juice led to high concentrations of lactic acid because of malolactic fermentation in both Type 2 and Type 3 sourdough productions. Moreover, the addition of apple juice increased the initial concentrations of the carbohydrates (fructose, glucose, and sucrose) and sugar alcohols (mannitol and sorbitol), which were exhausted upon backslopping or accumulated in the sourdough matrix, respectively. Baked goods produced using sourdoughs obtained from the Type 2 and Type 3 sourdough productions with the addition of juice at each backslopping step were significantly different in flavour from doughs supplemented with the respective juices and lactic acid and/or Type 3 sourdough productions with the addition of juice only at the start.

Human Pathogenic Candida Species Respond Distinctively to Lactic Acid Stress

Several Candida species are opportunistic human fungal pathogens and thrive in various environmental niches in and on the human body. In this study we focus on the conditions of the vaginal tract, which is acidic, hypoxic, glucose-deprived, and contains lactic acid. We quantitatively analyze the lactic acid tolerance in glucose-rich and glucose-deprived environment of five Candida species: Candida albicans, Candida glabrata, Candida parapsilosis, Candida krusei and Candida tropicalis. To characterize the phenotypic space, we analyzed 40–100 clinical isolates of each species. Each Candida species had a very distinct response pattern to lactic acid stress and characteristic phenotypic variability. C. glabrata and C. parapsilosis were best to withstand high concentrations of lactic acid with glucose as carbon source. A glucose-deprived environment induced lactic acid stress tolerance in all species. With lactate as carbon source the growth rate of C. krusei is even higher compared to glucose, whereas the other species grow slower. C. krusei may use lactic acid as carbon source in the vaginal tract. Stress resistance variability was highest among C. parapsilosis strains. In conclusion, each Candida spp. is adapted differently to cope with lactic acid stress and resistant to physiological concentrations.

PSVIII-23 Effects of different growth height on the yield, chemical composition, silage fermentation profile, in vitro and in situ digestibility of Broussonetia papyrifera

Abstract Broussonetia papyrifera (BP) is a woody roughage source with high protein content. The experiment was conducted to explore the effects of different growth height (GH) on the BP yield, chemical composition, silage fermentation profile, as well as ruminants in vitro and in situ digestibility of different parts of BP. The three different harvested GH of BP were 0.8, 1.2, and 1.6 m, respectively. Samples from leaf, stem, and whole plant of BP were collected (each one has three replicates), making silage, and detected the nutritional composition of them. The results were analyzed by one-way analysis of variance with Duncan’s multiple comparisons. Fresh weight increased with the GH increased (P < 0.05). No significant difference was observed in dry matter (DM) and crude protein (CP) yield of leaf, and CP yield of whole plant between 1.2 to 1.6 m GH (P > 0.05). With the increase of GH, neutral detergent fiber (NDF) of BP increased, while CP content decreased (P < 0.05). Stem had the highest NDF and acid detergent fiber (ADF) content, and the lowest CP content and buffer capacity. The BP silage fermentation quality was deteriorated (lactic acid content decreased and pH values increased) with GH increased. For the different parts of BP, leaf silage had the highest pH and stem silage had the highest lactic acid content (P < 0.05). The leaf and its silage had the highest in vitro dry matter digestibility and gas production compared to others. The BP in situ digestibility were corresponded with in vitro results. DM, CP, NDF, and ADF effective digestibility rates of whole plant with 1.2 m GH were 439.6, 455.1, 412.9, and 381.3 g/kg, respectively. In conclusion, the BP nutritional quality decreased with GH increased and it could be used as a potential feedstuff for ruminants.

Biopreservative potential of Lactobacillus strains in yoghurt dessert

The effects of Lactobacillus fermentum, L. helveticus, L. reuteri and L. rhamnosus on radical scavenging activity (DPPH and ABTS), lactate concentration and antibacterial potential (against E. coli, P. aeruginosa, S. sonnei, S. aureus and B. cereus) of yoghurt dessert were investigated during fermentation (37 °C for 24 h). The amount of protein carbonyls and the peroxide and anisidine values were also examined during cold storage period (5 °C for 10 days) in order to evaluate the oxidative stability of produced samples. During the fermentation period, L. helveticus had the greatest effect on increasing the antioxidant activity (DPPH and ABTS) of samples, while the highest lactic acid concentration (22.1 g/kg) and strains viability (9.5 log CFU/g) were related to the samples fermented by L. fermentum. Lactobacillus fermentum was the most effective antipathogen strain, while the lowest antibacterial activity observed for L. rhamnosus strain. Moreover, P. aeruginosa and S. sonnei exhibited the highest and B. cereus the lowest resistance to Lactobacillus strains, respectively. During the cold storage, the viability of LAB showed an increasing trend until the fourth day and then gradually decreased by 7–11%. The oxidative stability of all fermented samples was significantly (p ≤ 0.05) higher than that of control during the cold storage. The yoghurt dessert fermented by L. helveticus exhibited the lowest peroxide and anisidine values and the protein carbonyls concentration during the cold storage which it can be attributed to the higher antioxidant activity of this strain compared to others. It can be concluded that the Lactobacillus strains have the potential to be used as an effective biopreservation tool in yoghurt dessert production.

The Microbiota Dynamics of Alfalfa Silage During Ensiling and After Air Exposure, and the Metabolomics After Air Exposure Are Affected by Lactobacillus casei and Cellulase Addition.

Both inoculants treatment and enzyme treatment promote the reproduction of lactic acid bacteria (LAB) to produce enough lactic acid to lower pH in silage. The present study investigated the microbial community and metabolome in cellulase, Lactobacillus casei, and air treated alfalfa silage. Chopped and wilted alfalfa (first cutting, 29% dry matter) was ensiled without (CON) or with L. casei (1 × 106 cfu g–1 fresh matter) (LC) or cellulase (20,000IU, 0.5% of fresh matter) (CE) for 56 days, then exposed to air for 3 days (PO). Greater ensiling quality was observed in LC and CE, which had lower pH and higher lactic acid content than CON at 56 days of ensiling and 3 days post-oxygen exposure. Air exposure was associated with decreased lactic acid concentrations and increased yeast and mold counts in all silages. SEM showed that the structure of leaf epicuticular wax crystals were intact in fresh alfalfa, totally decomposed in CON silage, and partly preserved in CE and LC silage. Gas chromatography mass spectrometry revealed that 196 metabolites and 95 differential concentration were present in the 3 days air exposure samples. Most of these metabolites, mainly organic acids, polyols, ketones, aldehydes, are capable of antimicrobial activity. The bacterial communities were obviously different among groups and Lactobacillus developed to a dominant status in all silages. Lactobacillus became dominant in bacterial communities of LC and CE silages from days 7 to 56, and their relative abundances reached 94.17–83.93% at day 56, respectively. For CON silage, until day 56, Lactobacillus dominated the bacterial community with abundance of 75.10%. After 3 days of oxygen exposure, Lactobacillus and Enterococcus were predominant in CON, and Lactobacillus remained dominant in LC and CE silages. The results indicated that, compared to untreated silages, L. casei could be a priority inoculant for alfalfa silage to boost Lactobacillus abundance and improve fermentation quality. Our high-throughput sequencing and gas chromatography mass spectrometry results provide a deep insight into the bacterial community and metabolites in alfalfa silage.

Improvement of fermentation quality and cellulose convertibility of Napier grass silage by inoculation of cellulolytic bacteria from Tibetan yak (Bos grunniens).

To isolate and identify cellulolytic bacteria from yak rumen and further evaluate the effects of the isolates on the silage quality, structural carbohydrates degradation and cellulose convertibility of Napier grass silage. Two out of 218 strains were selected based on their most extensive transparent zone and the highest filter paper disintegration rate. The two isolates (JFL12 and JF85) could grow normally at 15-55°C, pH 3·0-7·0 and NaCl (3·0, 6·5%), and were identified as Enterococcus casseliflavus and Enterococcus faecalis by 16S rDNA sequence analysis, respectively. Napier grass was ensiled with no additive control (C), Lactobacillus plantarum (Lp), JFL12, JF85, JFL12+Lp and JF85+Lp for 3, 5, 7, 14, 30 and 60days. All inoculated silages had higher lactic acid content, lower pH, ammonia nitrogen (NH3 -N) and lignocellulose contents than the control silage. Silages treated with JFL12+Lp and JF85+Lp had the lowest pH and NH3 -N contents, the highest lactic acid content and lignocellulose degradation among all treatments. The isolates with or without Lp significantly (P<0·01) increased water soluble carbohydrates (WSC), glucose, fructose and sucrose contents as compared with the control silage. Silages treated with JFL12+Lp and JF85+Lp had higher glucose yield and cellulose convertibility than the other silages. Therefore, the application of isolates (JFL12 and JF85) with Lp had synergistic effects on accelerating the degradation of structural carbohydrates and improving the silage quality. Napier grass presents difficulty to ensiling due to its low WSC and high structural carbohydrates contents. The screened cellulolytic bacteria could be a candidate strain in improving fermentation quality and structural carbohydrates degradability of ensiled forages.

Effect of initial pH and substrate concentration on the lactic acid production from cassava wastewater fermentation by an enriched culture of acidogenic microorganisms.

Recently, cassava processing wastewater has been considered an alternative substrate for lactic acid production due to its appreciable carbohydrate levels. The authors carried out different batch reactor trials aiming to favor the production of lactic acid through the fermentation of non-sterilized cassava wastewater by an enriched culture of acidogenic microorganisms. To this end, the impact of different initial pHs (4.5, 5.0, 5.7, 6.5, and 7.0) and different initial substrate concentrations (10, 15.8, 30, 44.2, and 50g/L) in terms of glucose on lactic acid production yield (Y) was evaluated by applying the design of experiment (DoE) known as central composite rotatable design (CCRD). The highest rate of lactic acid production (40g/L) occurred with an initial pH of 6.5 and an initial substrate concentration of 50g/L. The maximum yield was higher in trials T1, T2, T4, T5, and T8, reaching values of 0.80, 0.62, 0.60, 0.96, and 0.70g/g, respectively. The maximum lactic acid productivity (P), of 0.60 and 0.73gL-1 hr-1 , was observed in trials T5 and T8, respectively. The enriched culture of acidogenic microorganisms was shown to favor the production of lactic acid, since the production of other acids, such as acetic and propionic acid, did not exceed 3.5 and 4.5g/L, respectively. © 2020 Water Environment Federation PRACTITIONER POINTS: Cassava wastewater presented potential to lactic acid production. The CCRD showed that highest lactic acid concentrations (40g/L). The adoption of cassava wastewater or manipueira as a substrate resulted in important information on the tendency to obtain value-added products such as lactic acid.

Physiological characterization of a new thermotolerant yeast strain isolated during Brazilian ethanol production, and its application in high-temperature fermentation

BackgroundThe use of thermotolerant yeast strains can improve the efficiency of ethanol fermentation, allowing fermentation to occur at temperatures higher than 40 °C. This characteristic could benefit traditional bio-ethanol production and allow simultaneous saccharification and fermentation (SSF) of starch or lignocellulosic biomass.ResultsWe identified and characterized the physiology of a new thermotolerant strain (LBGA-01) able to ferment at 40 °C, which is more resistant to stressors as sucrose, furfural and ethanol than CAT-1 industrial strain. Furthermore, this strain showed similar CAT-1 resistance to acetic acid and lactic acid, and it was also able to change the pattern of genes involved in sucrose assimilation (SUC2 and AGT1). Genes related to the production of proteins involved in secondary products of fermentation were also differentially regulated at 40 °C, with reduced expression of genes involved in the formation of glycerol (GPD2), acetate (ALD6 and ALD4), and acetyl-coenzyme A synthetase 2 (ACS2). Fermentation tests using chemostats showed that LBGA-01 had an excellent performance in ethanol production in high temperature.ConclusionThe thermotolerant LBGA-01 strain modulates the production of key genes, changing metabolic pathways during high-temperature fermentation, and increasing its resistance to high concentration of ethanol, sugar, lactic acid, acetic acid, and furfural. Results indicate that this strain can be used to improve first- and second-generation ethanol production in Brazil.

Effects of Chopping Length and Additive on the Fermentation Quality and Aerobic Stability in Silage of Leymus chinensis

The objective of this experiment was to evaluate the effects of the chopping length and additive on the fermentation characteristics and aerobic stability in silage of Leymus chinensis. L. chinensis was chopped to 1–2 cm and 4–5 cm, and immediately ensiled with the three treatments, i.e., 2% sucrose (fresh weight basis; SU), 1 × 105 cfu/g Lactobacillus plantarum (LP) or 1 × 105 cfu/g LP plus 2% sucrose (SU+LP). Silage treated with distilled water served as the control. After silage processing for 30 and 90 d, the fermentation quality of L. chinensis silage was evaluated. The composition of the fermentation products and the pH value in the silage were determined at 1, 3, 5 and 7 d after opening the silo. The results showed that in L. chinensis silage there was a lower pH value, higher lactic acid content and better aerobic stability at the 1–2 cm length than those at the 4–5 cm (p &lt; 0.001). When the chopping length was 4–5 cm, the addition of either LP or SU+LP increased the content of lactic acid and acetic acid, and decreased the pH value and butyric acid content, compared to those of the control and SU treatment (p &lt; 0.001). Furthermore, combination treatment of SU+LP performed better than LP alone, and the aerobic stability time of L. chinensis silage at 4–5 cm without any additives was the worst. In conclusion, enhanced fermentation quality and aerobic stability can be obtained by processing L. chinensis silage with the shorter length. When the L. chinensis is cut longer, e.g., 4–5 cm in this study, LP or SU+LP could be used as an effective method to improve the fermentation quality and aerobic stability of L. chinensis silage.

Lemon Exosome-like Nanoparticles-Manipulated Probiotics Protect Mice from C.d iff Infection.

SummaryClostridioides difficile (C. diff) is the leading cause of antibiotic-associated colitis. Here, we report that lemon exosome-like nanoparticles (LELNs) manipulated probiotics to inhibit C. diff infection (CDI). LELN-manipulated Lactobacillus rhamnosus GG (LGG) and Streptococcus thermophilus ST-21 (STH) (LELN-LS) decrease CDI mortality via an LELN-mediated increase in bile resistance and gut survivability. LELN-LS treatment increases the AhR ligands indole-3-lactic acid (I3LA) and indole-3-carboxaldehyde (I3Ald), leading to induction of IL-22, and increases lactic acid leading to a decrease of C. diff fecal shedding by inhibiting C. diff growth and indole biosynthesis. A synergistic effect between STH and LGG was identified. The STH metabolites inhibit gluconeogenesis of LGG and allow fructose-1,6-bisphosphate (FBP) to accumulate in LGG; accumulated FBP then activates lactate dehydrogenase of LGG (LGG-LDH) and enhances production of lactic acid and the AhR ligand. Our findings provide a new strategy for CDI prevention and treatment with a new type of prebiotics.

Effects of Sodium Formate and Calcium Propionate Additives on the Fermentation Quality and Microbial Community of Wet Brewers Grains after Short-Term Storage.

Simple SummaryThe objective of this study was to examine the effect of sodium formate and calcium propionate on the fermentation quality and microbial community of wet brewers grains (WBG) after short-term storage. Both additives improved the silage quality of WBG ensiled for 20 days to different extents. However, ensiled WBG treated with sodium formate had higher contents of dry matter, water-soluble carbohydrates, and neutral detergent fibers and better fermentation quality, rumen degradation, and microbial composition. The addition of sodium formate enhances the abundance of desirable Lactobacillus and reduces the abundance of undesirable microorganisms, including Clostridium. In summary, during short-term storage of high-moisture feed, sodium formate has a more beneficial preservation effect than an equivalent dose of calcium propionate.The objective of this research was to examine the effect of sodium formate (SF) and calcium propionate (CAP) on the fermentation characteristics and microbial community of wet brewers grains (WBG) after short-term storage. In the laboratory environment, fresh WBG was ensiled with (1) no additive (CON), (2) sodium formate (SF, 3 g/kg fresh weight), and (3) calcium propionate (CAP, 3 g/kg fresh weight) for 20 days. After opening, fermentation characteristics, chemical composition, rumen effective degradability, and the microbial community of ensiled WBG were analyzed. The addition of CAP had no effect on pH and lactic acid concentration and increased the concentrations of propionic acid; the SF group had the lowest pH and acetic acid, butyric acid, and ammonia nitrogen contents and the highest lactic acid concentration. After fermentation, the SF group had the highest contents of dry matter (DM), water-soluble carbohydrates (WSCs), and neutral detergent fiber (NDF). The contents of the three nutrients in the CAP group were significantly higher than those in the CON group. The addition of the two additives had little influence on the crude protein (CP) and acid detergent fiber (ADF) contents of the ensiled WBG. Two additives elevated in situ effective degradability of DM and NDF compared with the parameters detected in the CON group; WBG ensiled with SF had higher effective in situ CP degradability than that in the CON and CAP groups. The results of the principal component analysis indicate that the SF group and two other groups had notable differences in bacterial composition. The analysis of the genus level of the bacterial flora showed that the content of Lactobacillus in the SF group was significantly higher than that in the two other treatment groups, while the content of Clostridium was significantly lower than that in the two other treatment groups. Therefore, the addition of sodium formate can suppress the undesirable microorganisms, improve the fermentation qualities, and ensure that WBG is well preserved after 20 days of ensiling.

The Combined Effect of Pressure and Temperature on Kefir Production-A Case Study of Food Fermentation in Unconventional Conditions.

Food fermentation under pressure has been studied in recent years as a way to produce foods with novel properties. The purpose of this work was to study kefir production under pressure (7–50 MPa) at different temperatures (17–32 °C), as a case study of unconventional food fermentation. The fermentation time to produce kefir was similar at all temperatures (17, 25, and 32 °C) up to 15 MPa, compared to atmospheric pressure. At 50 MPa, the fermentation rate was slower, but the difference was reduced as temperature increased. During fermentation, lactic and acetic acid concentration increased while citric acid decreased. The positive activation volumes (Va) obtained indicate that pressure decreased the fermentation rate, while the temperature rise led to the attenuation of the pressure effect (lower Va). On the other hand, higher activation energies (Ea) were observed with pressure increase, indicating that fermentation became more sensitive to temperature. The condition that resulted in a faster fermentation, higher titratable acidity, and higher concentration of lactic acid was 15 MPa/32 °C. As the authors are aware, this is the second work in the literature to study the combined effect of pressure and temperature on a fermentative process.

Lactose-Induced Chronic Diarrhea Results From Abnormal Luminal Microbial Fermentation and Disorder of Ion Transport in the Colon.

Diarrhea is one of the major abdominal symptoms in lactose-intolerant subjects. The changes in the large intestinal luminal environment and disorder of the epithelial ion transport in lactose-induced diarrhea remain unclear. The present study aimed to investigate the effect of an incremental high-lactose diet (IHLD, 30%/40%/50%) on luminal microbiota, microbiota-derived metabolite concentrations and colonic ion transport. Gut microbiota were analyzed by 16S rRNA amplicon sequencing and the concentration of SCFAs by gas chromatography, galactose, lactose and lactic acid through assay kit; Ussing chamber was performed to detect basal and stimulated ion transport; The expression and location of SCFA transporters, the Na-H exchanger 3(NHE3), cystic fibrosis transporter regulater (CFTR) and NKCC1 in the colon mucosa were analyzed by western and immunostaining. The concentrations of lactose, galactose and lactic acid of the cecal content were markedly increased (P < 0.01) and SCFA concentration was significantly decreased (P < 0.01). This was associated with depletion of the Lachnospiraceae NK4A136 group and Ruminococcaceae UCG-005 and increased relative abundance of Lactobacillus, escherichia-shigella and megamonas in the cecal microbiota. The expression of monocarboxylate transporter 1 was decreased in the colonic mucosa of the IHLD group. Low NHE3 expression and phosphorylation levels, and decreases in delta basal short circuit current after apical Na+ removal in the colonic mucosa of the IHLD group contributed to Na+ accumulation in the lumen and decrease stimulated Cl– secretion with low CFTR and NKCC1 expression would compensate for water and electrolyte loss during the diarrhea process. These results indicated that the persistence of the diarrhea state was maintained by abnormal colonic microbiota fermentation leading to high concentrations of lactose, galactose and lactic acid and low SCFAs in the lumen, and decreased Na+ absorption with the low NHE3 expression and phosphorylation levels.

Effects of LAB inoculant and cellulase on the fermentation quality and chemical composition of forage soybean silage prepared with corn stover

AbstractThe objective of the present study was to evaluate the silage quality of forage soybean‐corn stover silage in the south of China. Forage soybean were combined manually with corn stover by ratios of R1 (25:75), R2 (50:50) and R3 (75:25) in fresh weight (FM) and ensiled in bag silos for 60 days at room temperature (20–25°C). All silages were treated without (control) or with lactic acid bacteria (LAB) inoculant (G, Lactobacillus plantarum and Lactobacillus buchneri, 105 cfu/g, of FM), cellulase (C, 0.02% of FM) and C + G. R1 silage had appropriate V‐score value with high lactic acid content and low pH value and ammonia‐N (NH3‐N) content, undetectable levels of propionic acid (PA) and butyric acid (BA). C and C + G reduced undesirable microorganisms of aerobic bacteria, yeasts and molds, resulting in improved nutritive value of R2 silage, as indicated by lower neutral detergent fiber and acid detergent fiber contents, and higher crude protein content, in vitro ruminal dry matter digestibility, gross energy and metabolizable energy values as compared to the control. Additives did not improve the quality of R3 silage with high pH value and NH3‐N content, BA and PA contents and undesirable microorganism counts. These results confirmed that high‐quality silage produced from mixtures (25:75) of forage soybean and corn stover in the south of China; additives (especially for C + G) could enhance the silage quality of forage soybean‐corn stover (50:50); and high proportion (&gt;75%) of forage soybean was difficult to ensile.

Cellulase interacts with Lactobacillus plantarum to affect chemical composition, bacterial communities, and aerobic stability in mixed silage of high-moisture amaranth and rice straw

The objective was to evaluate effects of Lactobacillus plantarum and/or cellulase on fermentation, aerobic stability and bacterial community of mixed high-moisture amaranth (AF) and rice straw (RS) silage. The mixtures were treated with no addition (C), L. plantarum (L), cellulase (F) and their combination (LF). Additives increased the abundances of Lactobacillus and reduced the abundances of Weissella, Pediococcus, Lactococcus, decreased pH, acetic acid, ammonia nitrogen and increased lactic acid concentration as compared to C silage over the ensiling period. The LF silage had the highest lactic acid concentration among all silages over the 7 d of ensiling and also the lowest abundance of Enterobacteriaceae over 30 d of ensiling. Aerobic spoilage occurred in C and LF silages after 2 d of aerobic exposure, whereas the L and F silages remained stable > 4 d. In conclusion, silage treated with LF showed best silage quality.

PLGA Barrier Materials from CO2. The influence of Lactide Co-monomer on Glycolic Acid Polyesters

The combination of the predicted polymer market growth and the emergence of renewable feedstocks creates a fantastic opportunity for sustainable polymers. To replace fossil-based feedstock, there are only three alternative sustainable carbon sources: biomass, CO2, and existing plastics (via mechanical and/or chemical recycling). The ultimate circular feedstock would be CO2: it can be electrochemically reduced to formic acid derivatives that subsequently can be converted into useful monomers such as glycolic acid. This work is part of the European Horizon 2020 project “Ocean” in which the steps from CO2 to glycolic acid are developed. Polyglycolic acid (PGA) and poly(lactide-co-glycolide) (PLGA) copolyesters with high lactic acid (LA) content are well-known. PGA is very difficult to handle due to its high crystallinity. On the other hand, PLGAs with high LA content lack good oxygen and moisture barriers. The aim of this work is to understand the structure–property relationships for the mostly unexplored glycolic acid rich PLGA copolymer series and to assess their suitability as barrier materials. Thus, PLGA copolymers with between 50 and 91 mol % glycolic acid were synthesized and their properties were evaluated. Increased thermal stability was observed with increasing glycolic acid content. Only those containing 87 and 91 mol % glycolic acid were semicrystalline. A crystallization study under non-isothermal conditions revealed that copolymerization reduces the crystallization rate for PLGA compared to polylactic acid (PLA) and PGA. While PGA homopolymer crystallizes completely when cooled at 10 °C·min–1, the copolymers with 9 and 13% lactic acid show almost 10 times slower crystallization, which is a huge advantage vis-à-vis PGA for processing. The kinetics of this process, modeled with the Jeziorny-modified Avrami method, confirmed those observations. Barrier property assessment revealed great potential for these copolymers for application in barrier films. Increasing glycolic acid content in PLGA copolymers enhances the barrier to both oxygen and water vapor. At room temperature and a relative humidity below 70% the PLGA copolymers with high glycolic acid content outperform the barrier properties of polyethylene terephthalate.

Fermentation Parameters and Quality of Sweet and Biomass Sorghum Silages With Doses of Vinasse

The cultivation of sorghum for silage production has gained more space each year because of its satisfactory nutritional characteristics, resistance to water deficit and adaptability to various types of soil. Thus, the use of sorghum silage has been an alternative for periods of low forage production, providing quality food for ruminants. In this context, the objective was to evaluate the fermentation parameters and quality of sweet and biomass sorghum silages added with doses of vinasse. The experiment was a 2 x 5 factorial completely randomized design with three replications of two sorghum species (sweet and biomass) and five doses of vinasse applied to the soil: 0; 50; 100; 150 and 200 m3 ha-1, totaling 30 experimental silos. For silage, sorghum species were harvested in the 105-day cycle, with 30.5 and 32.3 g kg-1 dry matter, for biomass and sweet sorghum, respectively. The results showed that the biomass sorghum silage showed higher dry mass production. However, the sweet sorghum silage presented a lower buffering capacity, NH3-N, and higher concentration of lactic acid. Doses of vinasse increased the content of crude protein, in vitro digestibility of dry matter and ether extract and reduced fiber fractions in both sorghum species, showing that both species can be used for silage production. Vinasse is a promising alternative to organic fertilizer, since the use of 200 m3 ha-1 positively influenced the fermentation parameters and nutritional value of the sorghum silages.

Varying ensiling conditions affect the fermentation quality and abundance of bacterial key players in lucerne silages

AbstractThe successful ensiling of lucerne (Medicago sativa L.) depends on a rapid acidification in the silo and consequently relies on a sufficient proliferation of, particularly homofermentative, lactic acid bacteria. Similarly, growth of spoilage bacteria, such as enterobacteria and clostridia, must be suppressed and silage additives are therefore frequently applied to promote favourable conditions during ensiling. Three silage additives or soil were applied during lucerne ensiling and investigated for their effects on silage quality characteristics and abundances of total bacteria as well as the bacterial key players Lactobacillus spp., homofermentative Lact. plantarum, heterofermentative Lact. buchneri, Clostridium spp. and Enterobacteriaceae after 30 days of storage. Inoculation with viable Lact. plantarum resulted in highest concentration of this species and excellent silage quality, i.e. high lactic acid concentration coupled with low acetic acid and ammonia-nitrogen concentrations. A sodium nitrite and hexamine-based additive did not support growth of lactic acid bacteria, which was also apparent by higher pH and low lactic acid concentration. No effect of treatments was found on spoilage-related enterobacteria and clostridia, even not when adding soil to lucerne to increase initial clostridial contamination. However, soil treatment resulted in increased ammonia-nitrogen and acetic acid concentrations. Consequently, among the bacterial key players, lactic acid bacteria concentrations were related to silage quality. Regarding spoilage bacteria, however, alterations in silage quality characteristics were not reflected in the abundances of enterobacteria and clostridia. Future investigations should underpin the present findings and help to understand how silage additives affect microbial key players and silage fermentation.

Synthesis of lactic acid from sugar palm trunk waste (Arenga pinnata): Preliminary hydrolysis and fermentation studies

Abstract. Erliana WH, Widjaja T, Altway A, Pudjiastuti L. 2020. Synthesis of lactic acid from sugar palm trunk waste (Arenga pinnata): Hydrolysis and fermentation studies. Biodiversitas 21: 2281-2288. The increasing problems of global energy and the environment are the main reasons for developing products with new techniques through green methods. Sugar palm trunk waste (SPTW) has potential as agricultural waste because of its abundant availability, but it is not used optimally. This study was aimed to determine the effect of various microorganisms on increasing lactic acid production by controlling pH and temperature conditions in the fermentation process. SPTW contains 43.88% cellulose, 7.24% hemicellulose, and 33.24% lignin. The lignin content in SPTW can inhibit reducing sugar formation; the pretreatment process should remove this content. In the study, the pretreatment process was conducted using acid-organosolv. In the acid pretreatment, 0.2 M H2SO4 was added at 120oC for 40 minutes; organosolv pretreatment using 30% ethanol (v/v) at 107oC for 33 minutes was able to increase cellulose content by 56.33% and decrease lignin content by 27.09%. The pretreatment was followed by an enzymatic hydrolysis process with a combination of commercial cellulase enzymes from Aspergillus niger (AN) and Trichoderma reesei (TR), with variations of 0:1, 1:0, 1:1, 1:2 and 2:1. The best reducing sugar concentration was obtained with an AN: TR ratio of 1:2 to form reducing sugar from cellulose. Subsequently, lactic acid fermentation was carried out using lactic acid bacteria at 37oC and pH 6 incubated for 48 hours. The highest lactic acid concentration (33.292 g/L) was obtained using a mixed culture of Lactobacillus rhamnosus and Lactobacillus brevis to convert reducing sugar become lactic acid.

Heating Effect on Rumen Digestion of Protein Feeds Fermented by Lactid Acid Bacteria

This study aimed to measure the in vitro digestibility of protein feeds as a product of Lactic acid bacteria (LAB) fermentation with different levels of molasses addition and incubation time. The LAB fermentation of protein feeds experiment had treatments given in the form of addition of molasses with levels of 0%, 3%, and 5% as well as at different incubation times of 0, 1, and 2 weeks. The best result of LAB fermentation was then protected from the rumen digestion by a heating treatment, carbohydrate, and fat addition. The parameter observed includes levels of pH and lactic acid production for LAB fermentation of protein feeds experiment and dry matter (DMD), organic matter (OMD), and crude protein digestibility (CPD) for protected rumen digestion experiment. Result showed that the lowest pH were 4.65±0.02, reached at the treatment with one week incubation (p<0.05) and 0% molasses addition (p<0.05). The highest lactic acid content were 1.82±0.10 mg/g fermentation feed based on treatment one weeks incubation (p<0.05) and 0% molasses addition (p>0.05). The highest content of protein showed at the treatment with two weeks incubation (p>0.05) and 5% molasses addition (p<0.05). Heating treatment had no significant compared to control, with the result respectively DMD 42.48±4.08%; 38.62±6.31%, OMD 53.21±4.74%; 49.71±5.62%, and CPD 38.15±4.71%; 34.88±2.72% (p>0.05). Fermentation could improve the nutrient quality of concentrate, but further research is needed to find ways to protect fermented concentrate.