Development of low-cost edible coatings based on polysaccharides with active lactic acid bacteria for the protection of fresh produce modeled using fresh cut apples.

The loss of fresh produce along the supply chain represents a significant contributor to environmental and economic burden. Although technological advances in distribution and storage have provided a means to reduce the loss of fresh produce, in resource-limited settings, these technologies may not be available. One attractive approach to help address this limitation is to use edible coatings to protect fresh produce from biotic and abiotic factors that cause food deterioration. Here, we developed edible coatings from materials that are cheap and easy to prepare: maize starch, κ-carrageenan, and agar as the matrix; glycerol as the plasticizer; and Lactobacillus plantarum TPB21.12 as the active ingredient. Using fresh cut apples as a model substrate, we found that maize starch coating retained color, agar coating delayed browning, and κ-carrageenan coating decreased mass shrinkage of the fresh cut apples. L. plantarum TPB21.12 remained viable in the edible coating suspensions during storage and was active against Escherichia coli TPB21.8, a model bacterium for biotic factor that causes food spoilage. The simplicity of the edible coating formulation and preparation method offers an attractive approach for applications to help protect fresh produce from deterioration and reduce food loss and waste generation.

Identification of a novel umami peptide in tempeh (Indonesian fermented soybean) and its binding mechanism to the umami receptor T1R.

Tempeh, a traditional Indonesian soybean product produced by fermentation, is especially popular because of its umami taste. In this study, a novel umami peptide GENEEEDSGAIVTVK (GK-15) was identified in the small peptide (<3 kDa) fraction of the water extract of tempeh using LC-MS/MS analysis and database-assisted identification. The umami taste of GK-15 was further validated using sensory evaluation, which suggested that GK-15 may be one of the key components contributing to the umami taste in tempeh. To rationalize the biological effect of GK-15, molecular docking of GK-15 into the N-terminal extracellular ligand-binding domain of the umami (T1R) receptor was performed. ZDOCK data showed that GK-15 could perfectly bind either to the open or closed conformation of T1R3. To the best of our knowledge, the present work is the first study to focus on the screening of umami peptides from tempeh.

DNA sequencing and homologous expression of a small peptide conferring immunity to gassericin A, a circular bacteriocin produced by Lactobacillus gasseri LA39.

Gassericin A, produced by Lactobacillus gasseri LA39, is a hydrophobic circular bacteriocin. The DNA region surrounding the gassericin A structural gene, gaaA, was sequenced, and seven open reading frames (ORFs) of 3.5 kbp (gaaBCADITE) were found with possible functions in gassericin A production, secretion, and immunity. The deduced products of the five consecutive ORFs gaaADITE have homology to those of genes involved in butyrivibriocin AR10 production, although the genetic arrangements are different in the two circular bacteriocin genes. GaaI is a small, positively charged hydrophobic peptide of 53 amino acids containing a putative transmembrane segment. Heterologous expression and homologous expression of GaaI in Lactococcus lactis subsp. cremoris MG1363 and L. gasseri JCM1131(T), respectively, were studied. GaaI-expressing strains exhibited at least sevenfold-higher resistance to gassericin A than corresponding control strains, indicating that gaaI encodes an immunity peptide for gassericin A. Comparison of GaaI to peptides with similar characteristics found in the circular bacteriocin gene loci is discussed.

Data in support of optimized production of angiotensin-I converting enzyme inhibitory peptides derived from proteolytic hydrolysate of bitter melon seed proteins.

VY-7 has been demonstrated as a potent ACE inhibitory peptide in the previous study [1]. In this article, we provide accompanying data about the identification of bitter melon seed proteins (BMSPs), and quantitative analysis and optimized production of VY-7 in BMSPs hydrolysate.

Screening, discovery, and characterization of angiotensin-I converting enzyme inhibitory peptides derived from proteolytic hydrolysate of bitter melon seed proteins.

In this study, new angiotensin-I converting enzyme (ACE) inhibitory peptides were comprehensively identified from a thermolysin digest of bitter melon (Momordica charantia) seed proteins. The hydrolysate was fractionated by reversed-phase high performance liquid chromatography (RP-HPLC), and the inhibitory activities of the resulting fractions were evaluated using ACE inhibitory assay. Two novel ACE inhibitory peptides (VY-7 and VG-8) were identified using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and database-assisted peptide sequencing. VY-7 and VG-8 were derived from momordin A and MAP30, respectively, and their IC50 values were as low as 8.64±0.60 and 13.30±0.62 µM, respectively. Lineweaver-Burk plots further indicated that VY-7, which showed the best IC50 value, acts as a competitive inhibitor. Notably, the content of VY-7 in crude thermolysin digest was determined to be as high as 14.89±0.88 µg/mg using LC-MS/MS quantification. In the spontaneously hypertensive rat (SHR) model, oral administration of VY-7 at 2mg/kg body weight significantly decreased the systolic blood pressure. The interaction between VY-7 and ACE was examined using molecular docking calculations and the results suggested that certain residues of VY-7 can fit perfectly into the S1, S1' and S2' regions of the binding pocket of ACE. BIOLOGICAL SIGNIFICANCE: One of the most common supportive therapies for treating hypertension is the use of synthetic drugs to inhibit ACE activity. Synthetic ACE inhibitors possess good antihypertensive effects, but come with accompanying side effects. Therefore, food-derived ACE inhibitory peptides are regarded as safer alternatives and are attracting much attention for hypertension treatment. In this study, we comprehensively identified peptides derived from bitter melon (Momordica charantia) seed proteins (BMSPs) using a shotgun proteomics approach. Based on results from an in vitro ACE inhibitory assay, two peptides (VY-7 and VG-8) derived from momordin A and MAP30 proteins, respectively, showed good ACE inhibitory activities. For VY-7, which showed the best IC50 value (8.64±0.60 µM), the inhibition type was determined to be competitive inhibition, as found using a Lineweaver-Burk plot. The novel ACE inhibitory peptide VY-7 (at 2mg/kg body weight) as well as the crude hydrolysate of BMSPs (at 10 mg/kg body weight) showed significant and moderate antihypertensive effects, respectively, in an animal model of hypertension, spontaneously hypertensive rats (SHRs). The present work demonstrated the screening of ACE inhibitory peptides from BMSPs and, as far as we know, VY-7 is the first well-characterized antihypertensive peptide derived from bitter melon seeds.