Comparative Study of Extracellular Proteolytic, Cellulolytic, and Hemicellulolytic Enzyme Activities and Biotransformation of Palm Kernel Cake Biomass by Lactic Acid Bacteria Isolated from Malaysian Foods

Effect of peptide formation during rapeseed fermentation on meat analogue structure and sensory properties at different pH conditions

This study aimed to modify the sensory properties of rapeseed protein concentrate using a combination of fermentation and high-moisture extrusion processing for producing meat analogues. The fermentation was carried out with Lactiplantibacillus plantarum and Weissella confusa strains, known for their flavour and structure-enhancing properties. Contrary to expectations, the sensory evaluation revealed that the fermentation induced bitterness and disrupted the fibrous structure formation ability due to the generation of short peptides. On the other hand, fermentation removed the intensive off-odour and flavour notes present in the native raw material. Several control treatments were produced to understand the reasons behind the hindered fibrous structure formation and induced bitterness. The results obtained from peptidomics, free amino ends, and solubility analyses strongly indicated that the proteins were hydrolysed by endoproteases activated during the fermentation process. Furthermore, it was suspected that the proteins and/or peptides formed complexes with other components, such as hydrolysis products of glucosinolates and polysaccharides.

Enzyme characterization of lactic acid bacteria isolated from duck excreta

Background and Aim

The production of lignocellulosic biomass waste in the agricultural sector of Indonesia is quite high annually. Utilization of lignocellulosic biomass waste through fermentation technology can be used as feed and biofuel. Fermentation technology requires the involvement of micro-organisms such as bacteria (lactic acid bacteria or LAB). LABs can be isolated from various sources, such as duck excreta. However, there have not been many reports of LAB from duck excreta. The present study aimed to characterize LAB enzymes isolated from duck excreta and obtain LAB enzymes with superior fermentation properties.

Materials and Methods

A total of 11 LAB cultures obtained from duck excreta in Yogyakarta, Indonesia, were tested. Enzyme characterization of each LAB was performed using the API ZYM kit (BioMérieux, Marcy-I'Etoile, France). The bacterial cell suspension was dropped onto the API ZYM™ cupule using a pipette and incubated for 4 h at 37°C. After incubation, ZYM A and ZYM B were dripped onto the API ZYM cupule, and color changes were observed for approximately 10 s under a strong light source.

Results

Esterase activity was moderate for all LABs. The activity of α-chymotrypsin, β-glucuronidase, α-fucosidase, and α-mannosidase was not observed in a total of 10 LAB. The phosphohydrolase and amino peptidase enzyme activity of seven LABs was strong. Only six LAB samples showed protease activity. The glycosyl hydrolase (GH) activity was observed in a total of 8 LAB, while the activity of 2 LAB was strong (Lactococcus lactis subsp. lactis K5 and Lactobacillus brevis M4A).

Conclusion

A total of 2 LABs have superior properties. L. lactis subsp. lactis K5 and L. brevis M4A have a high potential to be used in fermentation. They have the potential for further research, such as their effectiveness in fermentation, lignocellulose hydrolysis, feed additives, molecular characterization to detect specific enzymes, and their specific activities.

Production of snack bar enriched with paraprobiotics grown in banana peel medium, nutritional, sensory and quality parameters

Introduction

Objective: this research aims to develop a product with high sensory and nutritional quality to make paraprobiotics developed in banana peel consumable within the scope of waste evaluation. Methods: Lactobacillus plantarum and Lactobacillus casei probiotics were developed here by using banana peels as a medium, and paraprobiotics were obtained from these strains by the pasteurization method at 80 °C for 30 minutes. Two types of bars, with and without paraprobiotics, were produced, and the nutritional and sensory quality characteristics of the bars were examined. Results: bars with and without paraprobiotics showed similar properties in terms of energy, protein, carbohydrate, saturated fat, Ca, Mg, Zn, Fe, Na, and total sugar values and sensory criteria, but showed significantly different levels in terms of total fat, potassium, total fiber, total phenolic substance and antiradical activity values. Conclusion: bars with and without paraprobiotics are in the category of "protein added, protein source, or protein-containing", "high fiber", "low sodium" products.

An exopolysaccharide from Lactobacillus pentosus YY-112: structure and effect on the human intestinal microbiota

The development of novel prebiotics, which could regulate the intestinal microbiota, may help prevent and treat intestinal diseases. Here, we studied a homogeneous polysaccharide, LPE-2, produced by Lactobacillus pentosus YY-112 during fermentation. Methylation and gas chromatography-mass spectrometry analysis, combined with nuclear magnetic resonance results, suggested that the structural unit of LPE-2 comprises a branched mannan moiety and a linear glucan moiety. In vitro simulated intestinal fermentation showed that LPE-2 reduced harmful intestinal gas production and promoted short-chain fatty acid production (especially propionic acid). Moreover, it reduced the relative abundance of Escherichia-Shigella, increased that of Bifidobacterium and Lactobacillus, and had a stronger regulatory effect on intestinal flora in women than in men. The potential sex-specific prebiotic effects of LPE-2 on human intestinal health, were possibly related to its mannan branch with (1→2) and (1→3) linkages and backbones with flexible α configurations, which are sheared and degraded/utilized easier by Bifidobacterium and Lactobacillus.

Lactic acid bacteria as a tool for biovanillin production: A review

Vanilla is the most commonly used natural flavoring agent in industries like food, flavoring, medicine, and fragrance. Vanillin can be obtained naturally, chemically, or through a biotechnological process. However, the yield from vanilla pods is low and does not meet market demand, and the use of vanillin produced by chemical synthesis is restricted in the food and pharmaceutical industries. As a result, the biotechnological process is the most efficient and cost-effective method for producing vanillin with consumer-demanding properties while also supporting industrial applications. Toxin-free biovanillin production, based on renewable sources such as industrial wastes or by-products, is a promising approach. In addition, only natural-labeled vanillin is approved for use in the food industry. Accordingly, this review focuses on biovanillin production from lactic acid bacteria (LAB), which is generally recognized as safe (GRAS), and the cost-cutting efforts that are utilized to improve the efficiency of biotransformation of inexpensive and readily available sources. LABs can utilize agro-wastes rich in ferulic acid to produce ferulic acid, which is then employed in vanillin production via fermentation, and various efforts have been applied to enhance the vanillin titer. However, different designs, such as response surface methods, using immobilized cells or pure enzymes for the spontaneous release of vanillin, are strongly advised.

Biotransformation of gluten-free composite flour mediated by probiotics via solid-state fermentation process conducted under different moisture contents

Staple foods produced from composite flour are considered feasible to alleviate protein-energy malnutrition (PEM). However, one of the major limitations of composite flour is poor protein digestibility. The biotransformation process mediated by probiotics via solid-state fermentation (SSF) holds a promising potential to address the poor protein digestibility in composite flour. Yet, there is no report established in this regard to the best of our knowledge. Therefore, 4 strains of Lactiplantibacillus plantarum and Pediococcus pentosaceus UP2 isolated from Malaysian foods that were previously reported to produce versatile extracellular hydrolytic enzymes were employed to biotransform gluten-free composite flour derived from rice, sorghum, and soybean. The SSF process was performed under 30-60% (v/w) moisture content for 7 days, where samples were withdrawn at 24 h intervals for various analyses such as pH, total titratable acidity (TTA), extracellular protease activity, soluble protein concentration, crude protein content, and in vitro protein digestibility. The pH of the biotransformed composite flour showed a significant reduction from the initial range of pH 5.98-6.67 to the final pH of 4.36-3.65, corresponding to the increase in the percentage of TTA in the range of 0.28-0.47% to 1.07-1.65% from days 0 to 4 and remained stable till day 7 of the SSF process. The probiotics strains exhibited high extracellular proteolytic activity (0.63-1.35 U/mg to 4.21-5.13 U/mg) from days 0 to 7. In addition, the treated composite flour soluble protein increased significantly (p ≤ 0.05) (0.58-0.60 mg/mL to 0.72-0.79 mg/mL) from days 0 to 7, crude protein content (12.00-12.18% to 13.04-14.39%) and protein digestibility (70.05-70.72% to 78.46-79.95%) from days 0 to 4 of SSF. The results of biotransformation of 50% (v/w) moisture content were mostly comparable to 60% (v/w) moisture content, implying 50% (v/w) moisture content was the most suitable moisture content for the effective biotransformation of gluten-free composite flour mediated by probiotics via SSF since flour quality is better at lower moisture content. As for the overall performance, L. plantarum RS5 was ranked the best strain, attributed to the general improvement in the physicochemical properties of composite flour.

Variations of Soybean Meal and Corn Mixed Substrates in Physicochemical Characteristics and Microbiota During Two-Stage Solid-State Fermentation

Corn germ meal (CGM) and corn gluten feed (CGF) are the two main corn byproducts (CBs) obtained from corn starch extraction. Due to their high fiber content, low protein content, and severe imbalance of amino acid, CBs are unable to be fully utilized by animals. In this study, the effect of microorganism, proteases, temperature, solid–liquid ratio, and time on nutritional properties of CB mixture feed (CMF) was investigated with the single-factor method and the response surface method to improve the nutritional quality and utilization of CBs. Fermentation with Pichia kudriavzevii, Lactobacillus plantarum, and neutral protease notably improved the nutritional properties of CMF under the fermentation conditions of 37°C, solid–liquid ratio (1.2:1 g/ml), and 72 h. After two-stage solid-stage fermentation, the crude protein (CP) and trichloroacetic acid-soluble protein (TCA-SP) in fermented CMF (FCMF) were increased (p < 0.05) by 14.28% and 25.53%, respectively. The in vitro digestibility of CP and total amino acids of FCMF were significantly improved to 78.53% and 74.94%, respectively. In addition, fermentation degraded fiber and provided more organic acids in the CMF. Multiple physicochemical analyses combined with high-throughput sequencing were performed to reveal the dynamic changes that occur during a two-stage solid-state fermentation process. Generally, Ascomycota became the predominant members of the community of the first-stage of fermentation, and after 36 h of anaerobic fermentation, Paenibacillus spp., Pantoea spp., and Lactobacillales were predominant. All of these processes increased the bacterial abundance and lactic acid content (p < 0.00). Our results suggest that two-stage solid-state fermentation with Pichia kudriavzevii, Lactobacillus plantarum, and protease can efficiently improve protein quality and nutrient utilization of CMF.

Is Palm Kernel Cake a Suitable Alternative Feed Ingredient for Poultry?

Palm kernel cake (PKC), a by-product of oil extracted from palm nuts through expeller press or solvent extraction procedures is one of the highest quantities of locally available and potentially inexpensive agricultural product. PKC provides approximately 14-18% of crude protein (CP), 12-20% crude fiber (CF), 3-9% ether extract (EE), and different amounts of various minerals that feasible to be used as a partial substitute of soybean meal (SBM) and corn in poultry nutrition. Poultry's digestibility is reported to be compromised due to the indigestion of the high fiber content, making PKC potentially low for poultry feeding. Nevertheless, solid-state fermentation (SSF) can be applied to improve the nutritional quality of PKC by improving the CP and reducing CF content. PKC also contains β-mannan polysaccharide, which works as a prebiotic. However, there is a wide variation for the inclusion level of PKC in the broiler diet. These variations may be due to the quality of PKC, its sources, processing methods and value-added treatment. It has been documented that 10-15% of treated PKC could be included in the broiler's diets. The inclusion levels will not contribute to a negative impact on the growth performances and carcass yield. Furthermore, it will not compromise intestinal microflora, morphology, nutrient digestibility, and immune system. PKC with a proper SSF process (FPKC) can be offered up to 10-15% in the diets without affecting broilers' production performance.

A biorefinery approach for the production of ferulic acid from agroresidues through ferulic acid esterase of lactic acid bacteria

Ferulic acid is a known precursor for vanillin production but the significance of agro waste as substrates for its extraction, in combination with microbes is a less explored option. Various lactic acid bacteria were screened for the production of ferulic acid esterase (FAE) and Enterococcus lactis SR1 was found to produce maximum FAE (7.54 ± 0.15 IU/ml) in the synthetic medium under submerged fermentation. To make the process cost effective, various lignocellulosic agroresidues were evaluated for the production of FAE from the bacterium. It was found that wheat bran serves as the best substrate for FAE production (4.18 ± 0.12 IU/ml) from E. lactis SR1. Further, optimization of fermentation conditions for FAE production from E. lactis SR1 using wheat bran as carbon source led to an increase in the enzyme production (7.09 ± 0.21 IU/ml) by 1.5 fold. The FAE produced was used alone or in combination with commercial holocellulase for biological release of FA from the tested agroresidues. The highest release of FA (mg/g) by enzymatic extraction occurred in sugarbeet pulp (2.56), followed by maize bran (1.45), wheat bran (1.39) and rice bran (0.87), when both the enzymes (FAE and holocellulase) were used together. Alkaline extraction and purification of ferulic acid (FA) from these agro residues also showed that sugarbeet pulp contains the highest amount of FA (5.5 mg/g) followed by maize bran (3.0 mg/g), wheat bran (2.8 mg/g) and rice bran (1.9 mg/g), similar to the trend obtained in biological/enzymatic extraction of FA from these residues. Furthermore, the substrates were found to release higher reducing sugars when both commercial holocellulase and FAE were used in combination than by the use of holocellulase alone. Thus, FAEs not only release FA but also enabled hemicellulase and cellulase to release more sugars from plant material.

Enhancement of Versatile Extracellular Cellulolytic and Hemicellulolytic Enzyme Productions by Lactobacillus plantarum RI 11 Isolated from Malaysian Food Using Renewable Natural Polymers

Lactobacillus plantarum RI 11 was reported recently to be a potential lignocellulosic biomass degrader since it has the capability of producing versatile extracellular cellulolytic and hemicellulolytic enzymes. Thus, this study was conducted to evaluate further the effects of various renewable natural polymers on the growth and production of extracellular cellulolytic and hemicellulolytic enzymes by this novel isolate. Basal medium supplemented with molasses and yeast extract produced the highest cell biomass (log 10.51 CFU/mL) and extracellular endoglucanase (11.70 µg/min/mg), exoglucanase (9.99 µg/min/mg), β-glucosidase (10.43 nmol/min/mg), and mannanase (8.03 µg/min/mg), respectively. Subsequently, a statistical optimization approach was employed for the enhancement of cell biomass, and cellulolytic and hemicellulolytic enzyme productions. Basal medium that supplemented with glucose, molasses and soybean pulp (F5 medium) or with rice straw, yeast extract and soybean pulp (F6 medium) produced the highest cell population of log 11.76 CFU/mL, respectively. However, formulated F12 medium supplemented with glucose, molasses and palm kernel cake enhanced extracellular endoglucanase (4 folds), exoglucanase (2.6 folds) and mannanase (2.6 folds) specific activities significantly, indicating that the F12 medium could induce the highest production of extracellular cellulolytic and hemicellulolytic enzymes concomitantly. In conclusion, L. plantarum RI 11 is a promising and versatile bio-transformation agent for lignocellulolytic biomass.