Aspects of quercetin stability and its liposomal enhancement in yellow onion skin extracts.

Quercetin is a flavonoid that occurs in many types of fruit and vegetables and is stable for no longer than 4.5 h in the investigated pH range (6.0-8.0), even at 4 °C in the dark. At higher temperatures, the degradation/oxidation process is much faster. Simple but effective proliposomal encapsulation was used to protect the quercetin from environmental conditions such as pH. With this approach, 65 to 90% of pure quercetin and quercetin-rich onion extract was kept after >60 days under conditions that favoured its oxidation (pH 7.4). In addition, the encapsulated quercetin decreases the lipid peroxidation induced by pulsed UV light by >50%. At a mass ratio of 1:100 quercetin to lipids (w/w), the liposomes remained intact in solutions for six months. Quercetin in lipid bilayers simultaneously protects the unsaturated lipids from peroxidation.

Extraction of Polyphenols and Valorization of Fibers from Istrian-Grown Pomegranate (Punica granatum L.).

Pomegranate fruit is an ancient fruit that is used not only because of its deep-red color and tasty arils but also due to the health benefits of its extracts. Pomegranate is a valuable source of bioactive compounds, including colorful anthocyanins and other polyphenols. The main objective of the present study was to gain comprehensive knowledge of the phenolic composition and antioxidative activity of a new pomegranate cultivar, grown in Northwest Istria, a part of the North Adriatic coastal area. Various parts of the pomegranate fruit parts were extracted in 70% ethanol or water. Total phenolic content and antioxidative capacity were respectively determined with Folin-Ciocalteu reagent and ABTS radical. Phenolics were examined and analyzed with TLC, LC-MS, and HPLC. Pomegranate juice was prepared from red arils and after thermal treatment, the stability of anthocyanins was monitored for several months to understand the effect of storage. The highest total phenolics were determined in ethanol pomegranate peel extracts (30.5 ± 0.6 mg GAE/g DM), and water peel extracts exhibited the highest antioxidative activity (128 ± 2 µg TE/g DM). After five months of storage of thermally treated pomegranate juice, 50-60 percentage points increase in anthocyanin degradation was observed. Pomegranate peel was further tested as a sustainable inedible food source for papermaking. Due to the low content of cellulose and the high percentage of extractives, as well as a distinguished texture and appearance, the paper made from pomegranate peel is best suited for the production of specialty papers, making it particularly interesting for bioactives recovery, followed by material restructuring.

Comparative analysis of dietary fibre determination by AOAC 991.43 and AOAC 2011.25 for frequently consumed foods in Slovenia.

The definition of dietary fibre was modified by Codex Alimentarius commission in 2009, and now includes low molecular weight soluble dietary fibre. This prompted the development of new methods for determination of dietary fibre, such as AOAC 2009.01 and AOAC 2011.25. We compared the dietary fibre contents of 45 different foods from six food groups, as sources of dietary fibre frequently consumed in Slovenia. Dietary fibre was determined with methods AOAC 991.43 and AOAC 2011.25, and the results were compared. Majority of results show significantly higher dietary fibres when determined using AOAC 2011.25. Differences can be explained by low molecular weight soluble dietary fibre, which is measured by AOAC 2011.25. New methods for dietary fibre determination have impacts on national food composition databases, which remain mainly based on AOAC 991.43; defining the need to update food composition databases with data that include low molecular weight soluble dietary fibre.

Verifying the Use of Food Labeling Data for Compiling Branded Food Databases: A Case Study of Sugars in Beverages.

Branded food composition databases are an important tool for research, education, healthcare, and policy making, amongst others. Such databases are typically compiled using food labeling data without chemical analyses of specific products. This study aimed to verify whether the labeled sugar content in sugar-sweetened beverages (SSBs) corresponds to the actual sugar content in these products, thus enabling food monitoring studies to be conducted. A secondary objective was to determine the specific types of sugars in these SSBs. A case study was conducted using market share-driven sampling of these beverages from the Slovenian food supply. On the basis of nationwide yearly sales data, 51 best-selling products were sampled in 2020 and analyzed using high-performance liquid chromatography. This sales-driven approach to sampling has been shown to be very useful for conducting food monitoring studies. With the careful selection of a small proportion of available products, we finished with a manageable sample size, reflecting the composition of a majority (69%) of the national market share volume. The analyzed total sugar content was compared with labeled data, within the context of the European Union's regulatory labeling tolerances. In all samples, the sugar content was within the tolerance levels. The most common (N = 41) deviation was within ±10% of the labeled sugar content. In the subcategories, the differences between the analyzed and labeled median sugar contents were not statistically significant. Sucrose was most commonly (N = 36; 71%) used for sweetening, suggesting that the proportion of fructose in most SSBs was around 50%. A higher fructose content was only observed in beverages with fructose-glucose syrup or a higher content of fruit juice. The study results show that the labeled sugar content information in SSBs is reliable and can be used to compile branded food databases and monitor the nutritional quality of foods in the food supply.

Polysaccharide Hydrogels for the Protection of Dairy-Related Microorganisms in Adverse Environmental Conditions.

Adverse environmental conditions are severely limiting the use of microorganisms in food systems, such as probiotic delivery, where low pH causes a rapid decrease in the survival of ingested bacteria, and mixed-culture fermentation, where stepwise changes and/or metabolites of individual microbial groups can hinder overall growth and production. In our study, model probiotic lactic acid bacteria (L. plantarum ATCC 8014, L. rhamnosus GG) and yeasts native to dairy mixed cultures (K. marxianus ZIM 1868) were entrapped in an optimized (cell, alginate and hardening solution concentration, electrostatic working parameters) Ca-alginate system. Encapsulated cultures were examined for short-term survival in the absence of nutrients (lactic acid bacteria) and long-term performance in acidified conditions (yeasts). In particular, the use of encapsulated yeasts in these conditions has not been previously examined. Electrostatic manufacturing allowed for the preparation of well-defined alginate microbeads (180-260 µm diameter), high cell-entrapment (95%) and viability (90%), and uniform distribution of the encapsulated cells throughout the hydrogel matrix. The entrapped L. plantarum maintained improved viabilities during 180 min at pH 2.0 (19% higher when compared to the free culture), whereas, L. rhamnosus appeared to be less robust. The encapsulated K. marxianus exhibited double product yields in lactose- and lactic acid-modified MRS growth media (compared to an unfavorable growth environment for freely suspended cells). Even within a conventional encapsulation system, the pH responsive features of alginate provided superior protection and production of encapsulated yeasts, allowing several applications in lacto-fermented or acidified growth environments, further options for process optimization, and novel carrier design strategies based on inhibitor charge expulsion.

Waste streams in onion production: Bioactive compounds, quercetin and use of antimicrobial and antioxidative properties.

Onion production generates abundant waste with high contents of bioactive compounds. These might have several beneficial functional properties for fortification of foods. To understand the variety and potential for further use, we examined various parts of the plants (edible/inedible waste/outer skin of onion), as well as extraction in water/ethanol and by shaking/sonication. Quercetin content and antioxidant capacity were initially determined for extracts of edible and waste parts of red, yellow and white onions, and red shallots. Ethanol extracts of the waste fraction had the highest quercetin content and antioxidant capacity. Except white onion, which contained no quercetin, the dried waste ethanol extracts contained up to 15 mg quercetin g-1 and had an antioxidant capacity of nearly 40 mg Trolox equivalents g-1. Furthermore, the dried skin ethanol extract of yellow onion, which is commercially the most available fraction, contained 8 mg quercetin g-1, with antioxidant capacity of 25 mg Trolox equivalents g-1 and high antimicrobial activity. Dried yellow onion skin showed good stability for the quercetin content under various storage conditions (4, 25, 37, 40 °C; dark/light; dry/moist air/in water). Bacteria, bacterial spores, yeast and mould counts remained unchanged for dried onion skin over 5 days under storage conditions that can promote food spoilage, indicating exceptional microbial stability. Finally, two different applications are demonstrated for dried yellow onion skin: tablets for home use (tablets as more convenient form of storage and for simple dosing in cooking), and a stabilisation additive (prolonged shelf-life of olive oil). Both represent efficient and straightforward approaches through waste prevention and food fortification.

Stabilisation of Lutein and Lutein Esters with Polyoxyethylene Sorbitan Monooleate, Medium-Chain Triglyceride Oil and Lecithin.

Lutein is a challenging compound to incorporate into food, as it is poorly soluble and unstable in aqueous solutions. In this study, the aim was to prepare stable encapsulates of lutein and lutein esters using feasible and straightforward techniques. Fine suspensions based on polyoxyethylene sorbitan monooleate and medium-chain triglyceride oil micelle-like units with 3.45% lutein esters or 1.9% lutein equivalents provided high encapsulation efficiencies of 79% and 83%, respectively. Lutein encapsulated in fine suspensions showed superior stability, as 86% was retained within the formulation over 250 days at 25 °C in the dark. Under the same storage conditions, only 38% of lutein remained in corresponding formulations. Higher encapsulation efficiencies were achieved with lecithin emulsions, at up to 99.3% for formulations with lutein, and up to 91.4% with lutein esters. In lecithin emulsions that were stored for 250 days, 17% and 80% of lutein and lutein esters, respectively, were retained within the formulations.

In Vitro Comparison of the Bioactivities of Japanese and Bohemian Knotweed Ethanol Extracts.

Knotweed is a flowering plant that is native to temperate and subtropical regions in the northern hemisphere. We evaluated Japanese (Reynoutria japonica Houtt.) and Bohemian (Fallopia x bohemica) knotweed rhizome and flower ethanol extracts and compared them in terms of their biological activities. The specific polyphenols were identified and quantified using HPLC/DAD, and the antioxidant activity was determined using 2,2-diphenly-1-picrylhydrazyl (DPPH) and cellular antioxidant capacity assays. The anticancer activity was evaluated as the difference between the cytotoxicity to cancer cells compared with control cells. The antimicrobial activity was determined using bacteria and yeast. The antidiabetic activity was tested as the ability of the extracts to inhibit α-amylase. Both rhizome extracts were sources of polyphenols, particularly polydatin and (-)-epicatechin; however, the cellular assay showed the highest antioxidant capacity in the flower extract of F. bohemica. The PaTu cell line was the least sensitive toward all knotweed extracts. The flower extracts of both species were less toxic than the rhizomes. However, the activity of the tested extracts was not specific for cancer cells, indicating a rather toxic mode of action. Furthermore, all used extracts decreased the α-amylase activity, and the rhizome extracts were more effective than the flower extracts. None of the extracts inhibited bacterial growth; however, they inhibited yeast growth. The results confirmed that rhizomes of Reynoutria japonica Houtt. could become a new source of bioactive compounds, which could be used for the co-treatment of diabetes and as antifungal agents.

Enhanced Yield of Bioactivities from Onion (Allium cepa L.) Skin and Their Antioxidant and Anti-α-Amylase Activities.

There is increasing concern for reduction of the ecological impacts of industrial waste caused by fruits and vegetables. To reduce costs of onion waste disposal while obtaining value-added products, onion skin can be used to extract quercetin, a natural flavonoid with antioxidant, anti-inflammatory and anti-cancer effects. The aim was to optimize quercetin extraction from brown onion (Allium cepa L.) skin through investigation of the effects of different parameters on quercetin yield. Operational parameters for conventional maceration extraction and for ultrasound-assisted extraction were compared: solvent type, mass-to-liquid ratio, extraction time and temperature. Antioxidant capacity was determined using DPPH· radical scavenging assays and quercetin yield using HPLC/DAD. Anti-α-amylase activity of onion skin extracts was investigated using α-amylase inhibition assays. Optimal extraction conditions of quercetin from onion skin were obtained with maceration extraction, 50% ethanol, 1:100 mass-to-liquid ratio, 25 °C, for 15 min. Under these conditions, the antioxidant capacity (expressed as quercetin equivalents) was 18.7 mg/g and the mass fraction of quercetin was 7.96 mg/g. The onion skin extracts showed a dose-dependent relationship between dry extract concentration and α-amylase inhibition, which confirms that this onion skin extract can be considered as an anti-diabetes agent.

Part I. Polyphenols composition and antioxidant potential during 'Blaufränkisch' grape maceration and red wine maturation, and the effects of trans-resveratrol addition.

The effects of extended maceration (13 days) were investigated for extraction of trans-resveratrol and other phenolics from grapes of cultivar 'Blaufränkisch', and then during the subsequent maturation of the wine (250 days). Total phenolics and three subgroups of phenolics were followed. The concentrations of total phenolics, total flavonoids, and total anthocyanins, but not of total nonflavonoids, increased with extended maceration, and then decreased after 250 days of maturation. Trans- and cis-resveratrol concentrations increased following extended maceration and maturation (6.5, 2.9 mg/L, respectively). The maximum polydatin concentration was reached after only 6 days of maceration (10.9 mg/L). The antioxidant potential of the must increased following extended maceration (12.3 mmol DPPH2/L), and then remained unchanged for the red wine after maturation. Addition of trans-resveratrol to the red wine and into model solutions showed increased solubility and stability of trans-resveratrol in the red wines over the model solutions. Minor increases in antioxidant potential and better stability of malvidin-3-glucoside were also seen.

Effect of gentisic acid on the structural-functional properties of liposomes incorporating ß-sitosterol.

Multifunctional liposomes incorporating ß-sitosterol were developed for delivery of gentisic acid (GA). The interactions of both compounds with phospholipid bilayer were interpreted viaeffects of different ß-sitosterol content (0, 20 and 50 mol %) and different gentisic acid to lipid ratio (nGA/nlip from 10-5 to 1) on membrane fluidity and thermotropic properties. Multilamellar vesicles of phosphatidylcholines (with size range between 1350 and 1900 nm) effectively encapsulated GA (54%) when nGA/nlip was higher than 0.01. Suppression of lipid peroxidation was directly related to concentration of GA. The resistance to diffusion of gentisic acid from liposomes increased for ˜50% in samples incorporating 50 mol % ß-sitosterol compared to sterol-free liposomes. Finally, simulated in vitro gastrointestinal conditions showed that the release was mainly affected by low pH of simulated gastric fluid and the presence of cholates in simulated intestinal fluid, rather than by enzymes activity.

An Integrated Characterization of Jujube (Ziziphus jujuba Mill.) Grown in the North Adriatic Region.

Jujube (Ziziphus jujuba Mill.) has favourable horticultural properties including adaptation to arid conditions, abiotic and biotic stresses, as well as positive impact on human health. The present study describes the characterization of genetic diversity of the germplasm of jujube from the Istrian peninsula, the determination of important chemical compounds, antioxidative properties in relation to antibacterial and antifungal activities of jujube fruit extracts, and the determination of nutritional properties of jujube fruit. The results of the genetic analysis showed that most of the samples from the Istrian peninsula belong to two recently introduced varieties, 'Li' and 'Lang', and the most widespread local variety 'Navadna zizola'. The local variety has smaller fruit than the 'Li' and 'Lang' varieties, with thick and fleshy mesocarp. Chemical analysis indicated that fruits of the local variety contained a valuable source of dietary fibre ((9.7±0.6) g/100 g) and were rich in minerals such as (in g/100 g dry mass): potassium (829±51), calcium (177±11) and phosphorus (129±19). Aqueous extracts showed slight antibacterial activity, while ethanol extracts had higher mass fractions of phenolic compounds (expressed as gallic acid equivalents (GAE), 5.8-8.7 mg/g) than the aqueous extracts, but did not show antimicrobial activity. Compounds other than phenolic compounds in jujube fruit may be more biologically active. Based on the results of these analyses, the local Istrian jujube variety is a promising candidate for cultivation potential.

Protective effects of anthocyanins from bilberry extract in rats exposed to nephrotoxic effects of carbon tetrachloride.

This study examined the nephroprotective effects of 15 different anthocyanins from the bilberry extract on the acute kidney injury caused by CCl4. The acute nephrotoxicity in rats was induced 24 h after the treatment with a single dose of CCl4 (3 mL/kg, i.p.).The nephroprotective effects of the anthocyanins were examined in the animals that had been given the bilberry extract in a single dose of 200 mg of anthocyanins/kg daily, 7 days orally, while on the seventh day, 3 h after the last dose of anthocyanins, the animals received a single dose of CCl4 (3 mL/kg, i.p.) and were sacrificed 24 h later. When the nephrotoxicant alone was administered, it resulted in a substantial increase of the pro-oxidative (TBARS, CD, H2O2, XO, and GSSG) and pro-inflammatory markers (TNF-α, NO, and MPO), as well as a noticeable reduction of the antioxidant enzymes (CAT, SOD, POD, GPx, GST, GR) and GSH when compared to the results of the control group. Moreover, the application of CCl4 significantly influenced a reduction of the renal function, as well as an increase in the sensitive and specific injury indicators of the kidney epithelial cells (ß2-microglobulin, NGAL, KIM1/TIM1) in the serum and urine of rats. The pretreatment of the animals poisoned with CCl4 with the anthocyanins from the bilberry extract led to a noticeable reduction in the pro-oxidative and pro-inflammatory markers with reduced consumption of the antioxidant defence kidney capacity, compared to the animals exposed to CCl4 alone. Anthocyanins have been protective for the kidney parenchyma, with an apparent absence of the tubular and periglomerular necrosis, severe degenerative changes, inflammatory mononuclear infiltrates and dilatation of proximal and distal tubules, in contrast to the CCl4-intoxicated animals. The nephroprotective effects of anthocyanins can be explained by strong antioxidant and anti-inflammatory effects achieved through the stabilization and neutralization of highly reactive and unstable toxic CCl4 metabolites.

Enhanced yield of oleuropein from olive leaves using ultrasound-assisted extraction.

The aim of this study was to optimize the extraction of oleuropein from olive leaves through a systematic study of the effects of different parameters of ultrasound-assisted extraction (USAE) on the oleuropein yield, in comparison with conventional maceration extraction. A range of operational parameters were investigated for both conventional maceration extraction and USAE: solvent type, olive leaf mass-to-solvent volume ratio, and extraction time and temperature. Oleuropein yield was determined using high-performance liquid chromatography, with total phenolics content also determined. The optimized conditions (water-ethanol, 30:70 [v/v]; leaf-to-solvent ratio, 1:5 [w/v]; 2 hr; 25°C) provided ~30% greater oleuropein extraction yield compared to conventional maceration extraction. The total phenolics content obtained using the optimized USAE conditions was greater than reported in other studies. USAE is shown to be an efficient alternative to conventional maceration extraction techniques, as not only can it offer increased oleuropein extraction yield, but it also shows a number of particular advantages, such as the possibility of lower volumes of solvent and lower extraction times, with the extraction carried out at lower temperatures.

Antioxidative Activity of Methanolic and Water Extracts from the Hyperthermophilic Archaeon Aeropyrum pernix K1.

The hyperthermophilic archaeon Aeropyrum pernix has adapted to optimal growth under high temperatures in saline environments and under oxidizing conditions. In the present study, we focused on the antioxidative activity of proteins from A. pernix K1. Following high temperature methanol and water extractions of the protein from the biomass of A. pernix K1, the total sulphydryl groups and radical scavenging activities were investigated. The total protein in the methanolic extract was 36% lower and showed 10% fewer sulphydryl groups than that from the water extract. However, the radical scavenging activity of the water extract was four-fold greater than for the methanolic extract. The proteins of both of these extracts were separated by two-dimensional electrophoresis, and selected proteins were identified using mass spectrometry. The majority of these identified proteins were intracellular proteins, such as those involved in oxidative stress responses and osmotic stress responses, and proteins with hydrolase and dehydrogenase activities. These proteins are also common to most organisms, and included putative uncharacterized proteins.

Genetic, Biochemical, Nutritional and Antimicrobial Characteristics of Pomegranate (Punica granatum L.)Grown in Istria.

This study characterises the genetic variability of local pomegranate (Punica granatum L.) germplasm from the Slovenian and Croatian areas of Istria. The bioactive components and antioxidant and antimicrobial properties of ethanol and water extracts of different parts of pomegranate fruit were also determined, along with their preliminary nutritional characterisation. Twenty-six different genotypes identified with microsatellite analysis indicate the great diversity of pomegranate in Istria. The pomegranate fruit ethanol extracts represent rich sources of phenolic compounds (mean value of the mass fraction in exocarp and mesocarp expressed as gallic acid is 23 and 16 mg/g, respectively). The ethanol extracts of pomegranate exocarp and mesocarp showed the greatest antimicrobial activity against Candida albicans, Candida parapsilosis, Rhodotorula mucilaginosa, Exophiala dermatitidis and Staphylococcus aureus, and the same water extracts against S. aureus and Escherichia coli. To the best of our knowledge, this study represents the first report of the characterisation of pomegranate genetic resources from Istria at different levels, including the molecular, chemical, antimicrobial and nutritional properties.

Potential for brain accessibility and analysis of stability of selected flavonoids in relation to neuroprotection in vitro.

Natural food sources constitute a promising source of new compounds with neuroprotective properties, once they have the ability to reach the brain. Our aim was to evaluate the brain accessibility of quercetin, epigallocatechin gallate (EGCG) and cyanidin-3-glucoside (C3G) in relation to their neuroprotective capability. Primary cortical neuron cultures were exposed to oxidative insult in the absence and presence of the selected compounds, and neuroprotection was assessed through evaluation of apoptotic-like and necrotic-like cell death. The brain accessibility of selected compounds was assessed using an optimised human blood-brain barrier model. The blood-brain barrier model was crossed rapidly by EGCG and more slowly by C3G, but not by quercetin. EGCG protected against oxidation-induced neuronal necrotic-like cell death by ~40%, and apoptosis by ~30%. Both quercetin and C3G were less effective, since only the lowest quercetin concentration was protective, and C3G only prevented necrosis by ~37%. Quercetin, EGCG and C3G effectively inhibited α-synuclein fibrillation over the relevant timescale applied here. Overall, EGCG seems to be the most promising neuroprotective compound. Thus, inclusion of this polyphenol in the diet might provide an affordable means to reduce the impact of neurodegenerative diseases.

Anthocyanins in purple and blue wheat grains and in resulting bread: quantity, composition, and thermal stability.

The anthocyanin composition of blue (Triticum aestivum L., cv. Skorpion) and purple wheat (Triticum aethiopicum JAKUBZ cv. Abyssinskaja arrasajta cv. Abyssinskaja arrasajta), cultivated in the Czech Republic, and of the prepared whole blue and purple wheat bread was determined. In blue and purple wheat, 19 and 26 anthocyanins, respectively, were tentatively identified by liquid chromatography and mass spectrometry. The total content of anthocyanins determined in blue and purple wheat was 9.26 and 13.23 mgkg(-1), respectively. The breads were baked at 240 and 180 °C. Some significant differences in anthocyanins content were observed between breads prepared at different baking temperatures. The content of cyanidin-3-glucoside, delphinidin-3-glucoside and pelargonidin-3-glucoside was determinated in starting material, whole meal flours and baked breads. These kinds of wheat are suitable for baking bread, since intake of anthocyanins may play an important role in the prevention of human diseases.

Effects of industrial and home-made spread processing on bilberry phenolics.

Bilberries processed into spreads represent an important source of anthocyanins if these remain rich in the final product. The effects of thermal processing were studied with non-ground and ground bilberries processed into spreads according to industrial and home-made procedures. Samples were analysed by LC-DAD-MS/MS and LC-MS. The spreads had 28-60% less total phenolics, 4-62% less anthocyanins, and 1-fold to 2-fold more phenolic acids and total flavonols than the bilberries, but approximately equal flavanols. The home-made spread from ground bilberries had ca. 26% higher antioxidant activity. Delphinidin 3-glucoside and cyanidin 3-glucoside were taken through the two spread procedures, with their degradation to gallic acid (38-57%), protocatechuic acid (1-2%) and 2,4,6-trihydroxybenzaldehyde determined. The amounts of gallic and protocatechuic acids did not reflect well for anthocyanin degradation. The industrial spread procedure with non-ground bilberries is a more suitable procedure to maintain the final content of anthocyanins.

Binding of flavonoids to staphylococcal enterotoxin B.

Staphylococcal enterotoxins are metabolic products of Staphylococcus aureus that are responsible for the second-most-commonly reported type of food poisoning. Polyphenols are known to interact with proteins to form complexes, the properties of which depend on the structures of both the polyphenols and the protein. In the present study, we investigated the binding of four flavonoid polyphenols to Staphylococcal enterotoxin B (SEB) at pH 7.5 and 25 °C: (-)-epigallocatechin-3-gallate (EGCG), (-)-epigallocatechin (EGC), kaempferol-3-glucoside (KAM-G) and kaempferol (KAM). Fluorescence emission spectrometry and molecular docking were applied to compare experimentally determined binding parameters with molecular modeling. EGCG showed an order of magnitude higher binding constant (1.4 × 10(5) M(-1)) than the other studied polyphenols. Our blind-docking results showed that EGCG and similar polyphenolic ligands is likely to bind to the channel at the surface of SEB that is responsible for the recognition of the T-cell beta chain fragment and influence the adhesion of SEB to T cells.