Use and abuse of ascorbic acid—A review

The antiscorbutic¹ and ‘extra-antiscorbutic’ functions of ascorbic acid are reviewed. Although megatherapy remains unproven there is substantial evidence that ascorbic acid may affect metabolism in other ways, e.g. by enhancing heavy metal absorption from the alimentary canal. There is little generally accepted evidence that megadoses of ascorbic acid are of themselves toxic.     

Therapeutic and nutraceutical potential of rosmarinic acid—Cytoprotective properties and pharmacokinetic profile

Rosmarinic acid (RA) is a natural polyphenolic antioxidant derived from many common herbal plants. This compound displays several important biological properties, including anti-inflammatory, antiviral, antibacterial, antidepressant, anticarcionogenic, and chemopreventive properties. The importance of its activities and its possible application in processed foods as a natural antioxidant has reached a new interest levels in recent years. The health effects of this polyphenol depend greatly on both its intakes and bioavailability. This review focuses on the importance of RA as a dietary supplement, and summarizes its pharmacokinetics and metabolism, including the factors that limit its oral bioavailability which leads to a lower therapeutic action. Further experimental investigations are needed to optimize and enhance the oral bioavailability of this natural compound which consequently will help increasing therapeutic efficacy of RA in vivo.     

Effect of added α-ketoglutaric acid,pyruvic acid or pyridoxal phosphate on proteolyis and quality of Cheddar cheese

Cheddar cheese curds were supplemented with 1, 5 or 20 g of α-ketoglutarate or pyruvic acid or 1.2 g pyridoxal-5¹-phosphate/kg cheese curd. The higher levels of keto-acids (5 or 20 g/kg curd) caused undesirable changes in the physico-chemical properties of resultant cheese. All levels of α-ketoglutarate reduced the pH of the cheese and promoted syneresis during pressing, while pyruvic acid increased the pH of the cheese. The numbers of starter and non-starter lactic acid bacteria were not affected by the addition of keto-acids or pyridoxal-5¹-phosphate. α-Ketoglutarate or pyruvic acid, at 1 g/kg, or pyridoxal-5¹-phosphatase, at 1.2 g/kg cheese curd, did not influence primary proteolysis in the cheese. The highest and lowest concentrations of total and individual free amino acids were found in the cheeses treated with pyruvic acid or α-ketoglutarate, respectively. The concentrations of most amino acids were lower in the cheeses treated with pyridoxal-5¹-phosphate than in the control. The results of this study suggest that α-ketoglutarate and pyridoxal-5¹-phosphate enhanced the degradation of most amino acids in Cheddar cheese while pyruvic acid promoted the formation of amino acids. The cheeses treated with α-ketoglutarate were more mature than the control cheese of the same age while pyruvic acid-treated cheese had a better flavour than the control.     

Characterisation of inclusion complex of trans-ferulic acid and hydroxypropyl-β-cyclodextrin

The inclusion complex of trans-ferulic acid (FA) with hydroxypropyl-β-cyclodextrin (HP-β-CD) was prepared by the freeze-drying method and its characterisation was investigated by different analytical techniques including UV–visible spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffractometry, and scanning electron microscopy. All these approaches indicated that FA was able to form an inclusion complex with HP-β-CD, and the FA/HP-β-CD inclusion compounds exhibited different spectroscopic features and properties from FA. The stoichiometry of the complex was 1:1. The calculated apparent stability constant of the FA/HP-β-CD complex was 166.3 M⁻¹, and the water solubility of FA was significantly improved by phase solubility studies. Moreover, the irradiation-induced decomposition of FA in aqueous solution was markedly reduced by complexation with HP-β-CD. The results showed that HP-β-CD was a proper excipient for increasing solubility and stability of FA.     

Effect of acid concentration and treatment time on acid–alcohol modified jackfruit seed starch properties

The properties of starch extracted from jackfruit (Artocarpus heterophyllus Lam.) seeds, collected from west Assam after acid–alcohol modification by short term treatment (ST) for 15–30 min with concentrated hydrochloric acid and long term treatment (LT) for 1–15 days with 1 M hydrochloric acid, were investigated. Granule density, freeze thaw stability, solubility and light transmittance of the treated starches increased. A maximum decrease in the degree of polymerisation occurred in ST of 30 min (2607.6). Jackfruit starch had 27.1 ± 0.04% amylose content (db), which in ST initially decreased and then increased with the severity of treatment; in LT the effect was irregular. The pasting profile and granule morphology of the treated samples were severely modified. Native starch had the A-type crystalline pattern and crystalline structure increased on treatment. FTIR spectra revealed slight changes in bond stretching and bending. Colour measurement indicated that whiteness increased on treatment. Acid modified jackfruit seed starch can have applications in the food industry.     

Study of nonenzymic browning in α-amino acid and γ-aminobutyric acid/sugar model systems

The reactivities, in nonenzymic browning, of γ-aminobutyric acid (GABA), a non-protein amino acid with wide natural occurrence and potential health benefits as it occurs in foods, and of the α-l-amino acids arginine, glutamic acid, glutamine, leucine, lysine, and phenylalanine were investigated by heating equimolar mixtures of glucose and the cited amino acids at 110 °C at pH 6.0 for different times (0–4 h). Linear regression analysis indicated that the colour development in a GABA/glucose mixture was slower than that of a lysine/glucose mixture and comparable to that of a phenylalanine/glucose mixture. High-performance anion-exchange chromatography (HPAEC) with integrated pulsed amperometric detection (IPAD) showed that the decrease in GABA levels (ca. 10% after heating for 4 h) as a function of heating time was smaller than that of glucose (ca. 30% after heating for 4 h). At the same time, glucose to fructose isomerisation took place. After 20 min of heating at pH 6.0, all mixtures showed a fructose peak, the area of which increased with heating time. However, after correcting for fructose isomerisation, glucose losses were still higher than amino acid losses. In contrast to its precursor glutamic acid, GABA was stable during heating of a solution containing it alone. Heating of GABA-containing d-sugar solutions (xylose, fructose, glucose, maltose and sucrose) showed that the relative order of colour yield was pentose > hexose > disaccharides. As well as glucose to fructose isomerisation, HPAEC–IPAD allowed monitoring of the different isomerisation reactions occurring, and also disaccharide hydrolysis in the different GABA/sugar mixtures.     

Effects of dietary α-linolenic acid on the fatty acid composition, storage stability and sensory characteristics of pork loin

Effects of dietary α-linolenic acid on the fatty acid composition, storage stability and sensory characteristics of cooked pork were studied. Dietary α-linolenic acid (LNA) significantly (p < 0.05) increased the proportion of n−3 fatty acids and the degree of unsaturation in the neutral lipids and phospholipids. The increases in n−3 fatty acids were observed in the total lipids, triglycerides, phosphatidylethanolamine and phosphatidylcholine, and mainly consisted of C18:3n3, C20:5n3 and/or C22:5n3.The thiobarbituric acid reactive substances (TBARS) values (mg malondialdehyde per kg meat) of cooked vacuum packaged loins remained below 1.5, but in loose packaged loins TBARS values increased more than 3 times those of 0 time values during 2-day storage at 4 °C. The TBARS values of loins after LNA-enrichment were significantly higher than those of the control in both vacuum and loose packaging, and the increase of unsaturation in fatty acids had a strong prooxidant effect. The increase in dietary LNA enrichment increased oxidation (TBARS values) and had a detrimental effect on the acceptability of cooked pork loins held for 2 days in loose packaging.     

Effect of γ-radiation on green onion DNA integrity: Role of ascorbic acid and polyphenols against nucleic acid damage

The effect of γ-radiation on green onion DNA integrity, phenol content, oxygen radical absorbance capacity, employing pyrogallol red and fluorescein as probes, as well as ascorbic acid content has been evaluated. Measurements using thiazole orange-DNA fluorescence and agarose gel electrophoresis show that γ-radiation does not lead to an apparent DNA change in green onion. However, it was readily cleaved upon irradiation from the previously isolated nucleic acid. Furthermore, green onion exposure to γ-radiation produces slight increases in the polyphenol concentrations (163–188 μM Trolox eq.) and a decrease in the oxygen radical absorbance using fluorescein (from 245 to 200 Trolox eq.) Interestingly, a high ascorbic acid content (364 μM), which decreases by 40% after γ-ray exposure was measured by using pyrogallol-red-based oxygen radical absorbance capacity induction times from green onion aqueous extracts. Thus, our results suggest that ascorbic acid present in green onion plays a fundamental role in the plant antioxidant response toward γ-radiation exposure, while polyphenols remain largely unchanged, as revealed from oxygen radical absorbance capacity, employing pyrogallol red.     

Influence of preprocessing methods and fermentation of adzuki beans on γ-aminobutyric acid (GABA) accumulation by lactic acid bacteria

The effects of pre-processes (immersing, germinating, and cold shock) and fermentation conditions of adzuki beans on γ-aminobutyric acid (GABA) accumulation using mixed cultures of Lactococcus lactis and Lactobacillus rhamnosus were investigated in this study. Among the preprocessing methods, cold shock treatment resulted in the highest observed GABA content (201.2 mg/100 g); a 150-fold increase compared to the non-treated adzuki beans. The LAB strains grew rapidly in cold-treated adzuki bean substrates and reached 10⁸ cfu/ml after 24 h of fermentation at 30 °C. After optimization, the GABA yield reached 68.2 mg/100 ml; a 20-fold increase compared to the non-fermentation yield. The viable cell counts of LAB remained above 10⁸ cfu/ml after 28 days of storage at 4 °C. Our results suggest that the combination of cold shock pretreatment and fermentation by LAB may be used for the preparation of adzuki beans with high GABA content, which can then be used as a natural resource of functional foods.     

Contents of lovastatin, γ-aminobutyric acid and ergothioneine in mushroom fruiting bodies and mycelia

Lovastatin, γ-aminobutyric acid (GABA) and ergothioneine were analysed in mushrooms. Among fruiting bodies, Pleurotus ostreatus (Japan) and Agaricus bisporus contained the highest amount of lovastatin (606.5 and 565.4 mg/kg, respectively) whereas among mycelia, Cordyceps sinensis and Antrodia salmonea contained the highest (1365 and 1032 mg/kg, respectively). Among fruiting bodies, Flammulina velutipes and Boletus edulis contained the highest amount of GABA (229.7 and 202.1 mg/kg, respectively) whereas among mycelia, Cordyceps cicadae, C. sinensis and Agaricus blazei contained the highest (254.9, 220.5 and 200.4 mg/kg, respectively). Among fruiting bodies, Pleurotus citrinopileatus, P. ostreatus (Korea), P. ostreatus (Taiwan) and Pleurotus salmoneostramineus contained the highest amount of ergothioneine (2850.7, 1829.4, 1458.4 and 1245.0 mg/kg, respectively) whereas among mycelia, Pleurotus eryngii contained the highest (1514.6 mg/kg). Ergothioneine was detected in all samples. However, the Pleurotus genus contained considerably high amount of ergothioneine. Overall, these results might be related to their beneficial effects.     

Effect of ferulic acid and α-tocopherol antioxidants on properties of sodium caseinate edible films

Edible films, based on sodium caseinate containing three different concentrations of ferulic acid or α-tocopherol (20, 40 and 60 mg/g sodium caseinate), were obtained in order to evaluate the effect of these compounds on properties of the caseinate matrices. Special emphasis was placed on their effect on the films’ oxygen barrier properties, which are decisive in the prevention of the oxidation of foods containing lipids. Films were characterized as to their tensile, optical and surface properties as well as their barrier properties to water vapor, oxygen and aroma compounds (n-hexanal and n-hexanol). Ferulic acid was more efficient at reducing oxygen and n-hexanal permeability than α-tocopherol. Although ferulic acid slightly increased the stiffness of films at low concentration, in general, both antioxidants slightly reduce mechanical resistance, water vapor permeability, gloss and transparency of the films.     

Identification and quantification of acetic acid bacteria in wine and vinegar by TaqMan–MGB probes

A Real-Time PCR (RT-PCR) assay was developed using TaqMan minor groove binder (MGB) probes for the specific detection and quantification of five acetic acid bacteria (AAB) species (Acetobacter pasteurianus, Acetobacter aceti, Gluconacetobacter hansenii, Gluconacetobacter europaeus and Gluconobacter oxydans) in wine and vinegar. The primers and probes, designed from the 16S rRNA gene, showed good specificity with the target AAB species. The technique was tested on AAB grown in glucose medium (GY) and inoculated samples of red wine and wine vinegar. Standard curves were constructed with the five target species in all these matrices. Quantification was linear over at least 5 log units using both serial dilution of purified DNA and cells. When this technique was tested in GY medium and inoculated matrices, at least 10²–10³ cells/ml were detected. To quantify low populations of AAB in microbiologically complex samples, a PCR enrichment including part of the 16S–23S rRNA gene ITS region was needed to increase the amount of target DNA compared to non-target DNA.     

Identification of yeast and acetic acid bacteria isolated from the fermentation and acetification of persimmon (Diospyros kaki)

Persimmon (Diospyros kaki) is a seasonal fruit with important health benefits. In this study, persimmon use in wine and condiment production was investigated using molecular methods to identify the yeast and acetic acid bacteria (AAB) isolated from the alcoholic fermentation and acetification of the fruit. Alcoholic fermentation was allowed to occur either spontaneously, or by inoculation with a commercial Saccharomyces cerevisiae wine strain, while acetification was always spontaneous; all these processes were performed in triplicates. Non-Saccharomyces yeast species were particularly abundant during the initial and mid-alcoholic fermentation stages, but S. cerevisiae became dominant toward the end of these processes. During spontaneous fermentation, S. cerevisiae Sc1 was the predominant strain isolated throughout, while the commercial strain of S. cerevisiae was the most common strain isolated from the inoculated fermentations. The main non-Saccharomyces strains isolated included Pichia guilliermondii, Hanseniaspora uvarum, Zygosaccharomyces florentinus and Cryptococcus sp. A distinct succession of AAB was observed during the acetification process. Acetobacter malorun was abundant during the initial and mid-stages, while Gluconacetobacter saccharivorans was the main species during the final stages of these acetifications. Four additional AAB species, Acetobacter pasteurianus, Acetobacter syzygii, Gluconacetobacter intermedius and Gluconacetobacter europaeus, were also detected. We observed 28 different AAB genotypes, though only 6 of these were present in high numbers (between 25%–60%), resulting in a high biodiversity index.     

Speciation of arsenite and arsenate in rice grain – Verification of nitric acid based extraction method and mass sample survey

Arsenite and arsenate speciation was performed in 121 commercially purchased samples of 12 rice types to understand their relative relevance in rice grain. General effectiveness of a recently developed extraction protocol based on 0.28 M nitric acid at 95 °C was verified by checking the recovery of total grain arsenic and by comparing arsenic speciation in NIST-CRM-1568a, NMIJ-CRM-7503a and IMEP-107 with certificated and literature values. The arsenic speciation highlights the predominance of arsenite in 115 and dimethylarsinic acid in six samples and common minor components including arsenate, monomethylarsonic acid and two unknown arsenical species. Our data also indicate potential influences of other trace elements on As speciation in rice grain. Averagely, arsenite accounts for 90% of inorganic grain arsenic regardless of geographic origin, rice type, grain size, cultural practice and polish treatment. The high arsenite predominance indicates an elevated toxic effect of arsenic in rice than is perceived to date.     

Comparative effect of carnosic acid, BHT and α-tocopherol on the stability of squalene under heating and UV irradiation

Squalene is prone to auto-oxidation because it has a high content of unsaturated bonds. The effects of carnosic acid (CA) and two common antioxidants (butylated hydroxytoluene and α-tocopherol) on oxidative stability in squalene at different accelerated conditions (heating and UV irradiation) were compared. The investigation focused on the increase in peroxide and thiobarbituric acid-reactive substances. The changes in functional group contents were investigated by Fourier transform infrared spectroscopy, while the changes in squalene content and impurities situation were monitored by gas chromatography–mass spectrometry. The results show that CA was more effective in restraining squalene oxidation under heating, UV-A and UV-B irradiation. The antioxidant activity of CA was stronger than that of α-tocopherol and butylated hydroxytoluene. Squalene supplemented with 0.2 mg/g CA exhibited favorable antioxidant effects and is preferable for effectively avoiding oxidation.     

Production and characterization of α-linolenic acid enriched structured lipids from lipase-catalyzed interesterification

The purpose of this study was to enrich α-linolenic acid (ALA) on the triacylglycerol (TAG) molecules of the selected vegetable oils (soybean and corn oil) in order to synthesized structural lipid (SL) with low ω6 to ω3 ratio. SLs were synthesized by lipase-catalyzed interesterification of soybean (SO) and corn oil (CO) with perilla oil (PO). Lipozyme RM IM from Rhizomucor miehei (5% by weight of total substrate) was used for the reaction. The reaction was performed during 24 hr at 55°C in the stirred-batch type reactor with solvent free system. After 24 hr reaction the ratio of ω6 to ω3 in SL products dramatically decreased comparing to that of substrates (SO and CO) before the reaction. At sn-2 position, the contents of ALA were 25.99% in soybean-SL and 23.25% in corn-SL, respectively. According to the equivalent carbon number (ECN) of TAG profile, newly produced SLs were separated by reverse-phase high performance liquid chromatography (HPLC). These results indicated that lipase-catalyzed interesterification is effective to produce SL with low ω6 to ω3 ratio which might be used as health beneficial oil.