Enhancing enzymatic production efficiency of crude pectic oligosaccharides by pulsed electric field and study of prebiotic potential.

Orange juice by-products, including peel, segments, and seeds, account for more than 50% of the total mass. This study aims to valorize the peel and segments of Sai Nam Phueng (Citrus reticulata Blanco 'Sai Nam Phueng') orange juice by-products by producing crude pectic oligosaccharides (POS) with prebiotic potential using pulsed electric field (PEF)-assisted enzymatic treatment. PEF was performed for 5 min at field strengths of 10 and 7.5 kV/cm for orange peel powder (OPP) and orange segment powder (OSP), respectively, combined with Cellulase XL-531 at a concentration of 1.75%, pH 5.5, 40 °C for 2 h. The crude OPP-POS and OSP-POS yields were 19.16% and 17.51%, respectively, significantly higher than values obtained with PEF or enzymic hydrolysis singly. Thin layer chromatography results showed that the crude POS consisted of oligogalacturonic acids with various degrees of polymerization. Both POS products could enhance the growth of target probiotic bacteria and simultaneously produce short-chain fatty acids, especially propionic acid. Furthermore, the crude POS products also showed more than 90% resistance to simulated gastrointestinal digestion. These findings support the utilization of by-products from Sai Nam Phueng orange juice as a potential source for prebiotic production using PEF. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-023-05843-8.

Isolation and Identification of Antioxidant Peptides Derived from Cricket (Gryllus bimaculatus) Protein Fractions.

Crickets contain high protein content that can be used to improve nutrition but are less exploited. This study was conducted to isolate different Cricket Protein Fractions including albumin, globulin, glutelin, and prolamin. All fractions were characterized and hydrolyzed by commercial enzymes. The results showed that the glutelin fractions had the highest extraction yields with 53.9 ± 2.12% (p < 0.05). Moreover, glutelin hydrolysate fraction prepared by Alcalase with a 16.35 ±0.29% hydrolysis degree was selected for further purification because of their high antioxidant activities, including ABTS radical-scavenging activity (0.44-0.55 µmol Trolox eq./g) and metal chelating activity (1721.99-1751.71 µmol EDTA eq./g). Two active fractions, GA-1 (<3 kDa) and GA-2 (<3 kDa), were collected from the consecutive purification of glutelin hydrolysates, which included processes such as membrane ultrafiltration and gel filtration. The fractions were analyzed by LC-MS/MS to obtain 10 peptides with 3-13 amino acids identified as TEAPLNPK, EVGA, KLL, TGNLPGAAHPLLL, AHLLT, LSPLYE, AGVL, VAAV, VAGL, and QLL with a molecular weight range of 359.23-721.37 Da in the two fractions. The amino acid sequence shows a prevalence of hydrophobic amino acids (50-100%) such as valine and leucine in the peptide chains, accounting for its high antioxidant activity. In conclusion, cricket glutelin hydrolysate prepared by Alcalase can serve as an alternative source of potent edible bioactive peptides in functional food products.

Impacts of Electroextraction Using the Pulsed Electric Field on Properties of Rice Bran Protein.

The pulsed electric field (PEF) was applied to improve the extraction yield and properties of rice bran proteins from two rice varieties ("Kum Chao Mor Chor 107" and "Kum Doi Saket"). As compared to the conventional alkaline extraction, PEF treatment at 2.3 kV for 25 min increased the protein extraction efficiency by 20.71-22.8% (p < 0.05). The molecular weight distribution detected by SDS-PAGE and amino acid profiles of extracted rice bran proteins was likely unchanged. The PEF treatment influenced changes in the secondary structures of rice bran proteins, especially from the ß-turn to the ß-sheet structure. Functional properties of rice bran protein including oil holding capacity and emulsifying properties were significantly improved by PEF treatments by about 20.29-22.64% and 3.3-12.0% (p < 0.05), respectively. Foaming ability and foam stability increased by 1.8- to 2.9-fold. Moreover, the in vitro digestibility of protein was also enhanced, which was consistent with the increment of DPPH and ABTS radical-scavenging activities of peptides generated under in vitro gastrointestinal digestion (37.84-40.45% and 28.46-37.86%, respectively). In conclusion, the PEF process could be a novel technique for assisting the extraction and modification of the protein's digestibility and functional properties.

High Levels of Policosanols and Phytosterols from Sugar Mill Waste by Subcritical Liquefied Dimethyl Ether.

Extracting nutraceuticals with high value from bagasse, filter mud, and sugarcane leaves discarded as sugar mill by-products, is crucial for the development of a sustainable bio-economy. These by-products are important sources of policosanols and phytosterols, which have a cholesterol-lowering effect. This research focused on using a promising green technology, subcritical liquefied dimethyl ether extraction, with a low pressure of 0.8 MPa, to extract policosanols and phytosterols and on application of pretreatments to increase their contents. For direct extraction by subcritical liquefied dimethyl ether without sample pretreatment, the highest extraction yield (7.4%) and policosanol content were found in sugarcane leaves at 2888 mg/100 g, while the highest and lowest phytosterol contents were found in filter mud at 20,878.75 mg/100 g and sugarcane leaves at 10,147.75 mg/100 g, respectively. Pretreatment of filter mud by ultrasonication in hexane solution together with transesterification before the second subcritical liquefied dimethyl ether extraction successfully increased the policosanol content, with an extract purity of 60%, but failed to increase the phytosterol content.

The shortest innovative process for enhancing the S-allylcysteine content and antioxidant activity of black and golden garlic.

Black garlic is a type of heat-treated garlic for which the traditional process is extremely simple yet time-consuming, taking more than one month. The purpose of this research was to reduce the processing time of black garlic while maintaining a high level of S-allylcysteine (SAC), a black garlic quality indicator. The fresh garlic was pre-treated with CaCl2 and frozen before being further incubated at two different temperatures (60 and 80 °C) with a relative humidity of 65% and 80% RH. Results showed that sequential pre-treatment and incubation at 80 °C and 80% RH for 1 week yielded 874.26 mg of SAC/100 g dry weight with an antioxidant activity of 5390 and 25,421 mg Trolox/100 g for DPPH and ABTS assays, respectively. This process shortened the processing time of black garlic by about 4-times. The batch processed at 60 °C and 65% RH for 1 week provided the highest SAC content of about 1772 mg/100 g dry weight, which was 2-times higher than in incubation at 80 °C and 80% RH for 1 week. The colour of this garlic was golden, so we call this new processed garlic product "golden garlic".

Optimization of enzymatic hydrolysis by alcalase and flavourzyme to enhance the antioxidant properties of jasmine rice bran protein hydrolysate.

This study aimed to optimize the hydrolysis conditions for producing jasmine rice bran protein hydrolysate (JBH) using response surface methodology (RSM). The independent variables were the ratio of flavourzyme to alcalase (Fl:Al; 0: 100 to 15: 85; 2.84% enzyme concentration) and hydrolysis time (60-540 min). The optimum hydrolysate was obtained at an Fl:Al ratio of 9.81: 90.19 for 60 min, since it enabled high amounts of protein, high antioxidant activity and more low molecular weight proteins. The experimental values obtained were a degree of hydrolysis (DH) of 7.18%, a protein content of 41.73%, an IC50 for DPPH of 6.59 mg/mL, an IC50 for ABTS of 0.99 mg/mL, FRAP of 724.81 mmol FeSO4/100 g, and 322.35 and 479.05 mAU*s for peptides with a molecular weight of < 3 and 3-5 kDa, respectively. Using a mixture of enzymes revealed the potential of mixed enzymes to produce JBH containing more small peptides and high antioxidant activity.

On-package indicator films based on natural pigments and polysaccharides for monitoring food quality: a review.

Deterioration of food quality and freshness is mainly due to microbial growth and enzyme activity. Chilled fresh food, especially meat and seafood, as well as pasteurized products, rapidly lose quality and freshness during packing, distribution and storage. Real-time food quality monitoring using on-package indicator films can help consumers make informed purchasing decisions. Interest in the use of intelligent packaging systems for monitoring safety and food quality has increased in recent years. Polysaccharide-based films can be developed into on-package indicator films due to their excellent film-forming properties and biodegradability. Another important component is the use of colorants with visible color changes at various pH levels. Currently, natural pigments are receiving increased attention because of their safety and environmental friendliness. This review highlights the recent findings regarding the role of natural pigments, the effects of incorporating natural pigments and polysaccharides on properties of indicator film, current application and limitations of on-package indicator films based on polysaccharides in some foods, problems and improvement of physical properties and color conversion of indicator film containing natural pigments, and development of polysaccharide-based pH-responsive films. © 2022 Society of Chemical Industry.

Optimization of the pulse electric field assisted extraction of black rice grain for antioxidant and sirtuin1 enzyme stimulation activities.

Cyanidin-3-glucoside (C3G) and peonidin-3-glucoside (P3G) in black rice grain (BRG) demonstrate many beneficial health effects, including antioxidant and anti-aging properties. This research aimed to study on pulsed electric field assisted water extraction (PEF-AWE) on BRG using pre-treatment technique, which was determined for enhanced yields of C3G and P3G, antioxidant and sirtuin1 enzyme stimulation activities. The effects of operating parameters for PEF-AWE (intensity of electric field, X1: 3-5 kV/cm, number of pulse, X2: 1000-3000 pulse and BRG/water ratio, X3: 0.1-0.5 g/mL) were determined using regression analysis and optimized PEF-AWE condition using the response surface methodology. Regression models showed the intensity of electric field and BRG/water ratio were the strong influence parameters significantly on C3G (p < 0.01). The results highlighted optimized conditions of PEF-AWE followed by 5 kV/cm, 3000 pulse and 0.5 g/mL leading to achieve higher C3G (92.59 ± 4.79 mg/g) and P3G (4.59 ± 0.27 mg/g) than no pre-treatment by PEF process, approximately 60%. Additionally, PEF extracts of BRG can modulate the ability of surtuin1 enzyme to deacetylate substrate proteins (26.78 ± 0.50 FIR). Thus, PEF-AWE can be applied to produce BRG extract as natural antioxidant compound and functional ingredient.

Microwave-assisted enzymatic hydrolysis to produce xylooligosaccharides from rice husk alkali-soluble arabinoxylan.

The prebiotic properties of xylooligosaccharides (XOS) and arabino-xylooligosaccharides (AXOS) produced from rice husk (RH) using microwave treatment combined with enzymatic hydrolysis were evaluated. The RH was subjected to microwave pretreatment at 140, 160 and 180 °C for 5, 10 and 15 min to obtain crude arabinoxylan (AX). Increasing microwave pretreatment time increased sugar content. Crude AX was extracted with 2% (w/v) sodium hydroxide at 25 °C for 24 h and used as a substrate for XOS production by commercial xylanases. Results showed that oligosaccharides produced by Pentopan Mono BG and Ultraflo Max provided xylobiose and xylotriose as the main products. AXOS was also present in the oligosaccharides that promoted growth of Lactobacillus spp. and resisted degradation by over 70% after exposure to simulated human digestion.

Two-stage processing for xylooligosaccharide recovery from rice by-products and evaluation of products: Promotion of lactic acid-producing bacterial growth and food application in a high-pressure process.

In this study, we attempted to maximize arabinoxylan conversion into xylooligosaccharide (XOS) from rice husk and rice straw using two saccharification processes and evaluate the promotion of lactic acid-producing bacterial growth, including an investigation of the role of prebiotics in protecting probiotic bacteria in rice drink products in a high-pressure process (HPP). Hydrothermal treatment followed by enzymatic hydrolysis was designed for XOS recovery from rice husk arabinoxylan (RH-AX) and rice straw arabinoxylan (RS-AX). The hydrothermal treatment performed at 170 °C for 20 min and 180 °C for 10 min was the optimal condition to produce XOS liquor from rice husk and rice straw, respectively. Pentopan mono BG successfully recovered XOS from rice husk and rice straw residues at 50 °C, pH 5.5, an enzyme concentration of 50 U and 100 U/g substrate for 24 h. This design converted 92.17 and 88.34% (w/w) of initial RH-AX and RS-AX into saccharides, which comprised 64.01 and 59.52% of the XOS content, respectively. Rice husk xylooligosaccharide (RH-XOS) and rice straw xylooligosaccharide (RS-XOS) had degrees of polymerization ranging from 2 to 6 with some arabino-xylooligosaccharides. RH-XOS and RS-XOS were used to examine the promotion of the growth of lactic acid-producing bacteria strains in the presence of other prebiotics. RH-XOS and RS-XOS strongly promoted the growth of Lactobacillus sakei and Lactobacillus brevis, while other species showed weak to moderate growth. This study represents the first report of the powerful effect of Lactococcus lactis KA-FF1-4 on altering the utilization of XOS but not xylose. Furthermore, for the first time, we reported the capability of XOS to protect probiotics in rice drinks under high-pressure conditions. RH-XOS and RS-XOS resulted in the highest viability of approximately 11 log cfu/mL and exhibited no significant difference compared with the non-HPP treatment. Hence, rice husk and rice straw can be utilized as alternative prebiotic sources that provide biological activity and food applications in the HPP industry.

Antimicrobial and antioxidant activities of defatted Moringa oleifera seed meal extract obtained by ultrasound-assisted extraction and application as a natural antimicrobial coating for raw chicken sausages.

Moringa oleifera is a medicinal plant, and its seed oil is known to have high antioxidant properties. The byproduct obtained after oil extraction is called Moringa oleifera seed meal (MoSM), whose potential bioactivity has not been sufficiently documented. Therefore, this study was undertaken with the aim of identifying Moringa oleifera seed meal extract (ME) as a natural antibacterial and antioxidant alternative. First, the effect of solvent extraction of MoSM with 60% (v/v) ethanol combined with ultrasound (UAE) was determined at the sample-to-solvent ratio of 1: 10, with different time and power combinations of UAE. The lowest minimum inhibitory concentration (MIC) exhibited by ME at 200 W and 20 min (ME200/20) against both Escherichia coli among the gram-negative bacteria and Bacillus cereus among the gram-positive bacteria was 3.12 mg/g. The leakage of intracellular constituents as well as the damage of the B. cereus cells after being treated with ME were confirmed by measuring the absorbance of the supernatant at 260 and 280 nm and observation of the cells under a scanning electron microscope. Moreover, the highest total phenolic content was also recorded with ME200/20 at 460 mg gallic acid equivalent/g of extract, and the subsequent significantly higher (p < 0.05) antioxidant activity was determined to be 11.18 and 9.20 mg acetic acid equivalent/g of extract by 2,2-diphenyl-1-picrylhydrazyl and ferric reducing antioxidant power assays, respectively. The high-performance liquid chromatography results showed that gallic acid and vanillic acid were predominantly present in the extract, followed by quercetin, sinapic acid and chlorogenic acid. Interestingly, caffeic acid appeared in the sample treated with UAE only. The extract was finally applied with a chitosan-based coating to evaluate the antimicrobial activity against E. coli and B. cereus on raw chicken sausages in the concentration range of 1-5%. Incorporating 3% extract could inactivate B. cereus and E. coli for a 1.4 log reduction on day 3 and a 1.78 log reduction on day 6 of storage and, further, could significantly suppress the growth of both bacteria until day 9. Thus, this study confirmed the strong antibacterial and antioxidant properties of ME and its potential use in real food systems as a natural food antibacterial agent.

Effects of high-pressure carbonation on intracellular ATP and NADH levels and DNA damage in Escherichia coli cells.

In order to understand the microbial inactivation mechanism of high-pressure carbonation (HPC), we examined the changes in the activity of the respiratory chain and DNA damage in Escherichia coli cells. HPC was performed under 1-6 MPa at 30°C for 1 min. The increase in CO2 pressure decreased the number of viable cells of E. coli, intracellular ATP, and intracellular NADH, and increased the number of apurinic/apyrimidinic sites. These results indicate that HPC has a detrimental effect on the functioning of the respiratory chain in E. coli and induces DNA damage, which could result in the death of the bacterial cells.

Combined effects of carbonation with heating and fatty acid esters on inactivation and growth inhibition of various bacillus spores.

The effects of carbonation treatment (1 to 5 MPa, 30 min) plus heat treatment (30 to 80°C, 30 min) in the presence of various fatty acid esters (FAEs; 0.05 and 0.1%, wt/vol) on counts of viable Bacillus subtilis spores were investigated. FAEs or carbonation alone had no inactivation or growth inhibition effects on B. subtilis spores. However, carbonation plus heat (CH; 80°C, 5 MPa, 30 min) in the presence of mono- and diglycerol fatty acid esters markedly decreased counts of viable spores, and the spore counts did not change during storage for 30 days. The greatest decrease in viable spore counts occurred in the presence of monoglycerol fatty acid esters. Under CH conditions, inactivation and/or growth inhibition occurred at only 80°C and increased with increasing pressure. The greatest decrease in spore counts (more than 4 log units) occurred with CH (80°C, 5 MPa, 30 min) in the presence of monoglycerol fatty acid esters. However, this treatment was less effective against Bacillus coagulans and Geobacillus stearothermophilus spores.

The effect of low-pressure carbonation on the heat inactivation of Escherichia coli.

The heat inactivating effect of low-pressure carbonation (LPC) at 1 MPa against Escherichia coli was enhanced to 3.5log orders. This study aimed to investigate the mechanisms of this increase in heat inactivation efficiency. The increased inactivation ratio was found to be the result of LPC-induced heat sensitization. This sensitization was not due to any physical damage to the cells as a result of the treatment. Following the depletion of intracellular ATP, the failure of the cells to discard protons caused an abnormal decrease in the intracellular pH. However, in the presence of glucose, the inactivation ratio decreased. In addition, a further increase in inactivation of more than 2log orders occurred in the presence of the protein synthesis inhibitor chloramphenicol. Hence, the decreased heat resistance of E. coli under LPC was most likely due to a depletion of intracellular ATP and a decreased capacity for protein synthesis.