Thermal degradation kinetics of aqueous anthocyanins and visual color of purple corn (Zea mays L.) cob

Purple corn cob was the byproduct during the corn processing. Thermal degradation kinetics and Hunter color parameters (a, b, C, h° and ΔE) of aqueous anthocyanins from purple corn cob were studied at selected temperatures (70 °C, 80 °C and 90 °C) at pH 4.0. The results indicated that the thermal degradation of anthocyanin and Hunter color C, a and ΔE parameters followed the first-order reaction kinetics, while Hunter color h° and b parameters followed zero-order reaction kinetics. The calculated values of activation energies (Ea) were 18.3, 35.9, 37.1, 31.6, 34.9 and 30.0 kJ/mol for anthocyanins, C, a, ΔE, h° and b parameters, respectively. The higher Ea indicated that greater temperature sensitivity of visual color as compared to anthocyanins content. The degradation of anthocyanins showed positive correlation with C (R² > 0.909), a (R² > 0.860) and ΔE (R² > 0.940), while the degradation of anthocyanins showed negative correlation with h° (R² > 0.828) and b (R² > 0.735) during heating.

Industrial relevance

Purple corn cob was the byproduct during the corn processing. Purple corn cob is dark purple to almost black color due to its high content of anthocyanins, which makes this byproduct a good source of anthocyanins. In this study, the excellent linear correlation between Hunter color parameters (a, b, C, h° and ΔE) and content of anthocyanins showed that the Hunter color parameters may also be used instead of anthocyanins content during heating. The advantage of using the visual Hunter color parameters may be measured as on-line quality control parameters during thermal processing of food industry.     

Composition,antimicrobial activity,and antiproliferative capacity of anthocyanin extracts of purple corn (<Emphasis Type="Italic">Zea mays</Emphasis> L.) from China

The composition, antimicrobial activity, and antiproliferative capacity of the anthocyanin extracts from five purple corn hybrids (Zea mays L.) from China were evaluated. The total phenolic content and total anthocyanin content of the anthocyanin extract from Chinese purple corn (Zhuozhou, Hebei Province, China) (EZPC) were higher than that of the other four hybrids. Moreover, the antimicrobial activity of EZPC was stronger than that of the other four hybrids against Salmonella enteritidis, Staphylococcus aureus, and Candida albicans. Furthermore, EZPC showed the antiproliferative capacity against the colon-cancer-cell HT-29 in a dose dependent manner with IC₅₀ of 0.525 μg/mL of the anthocyanin content. The antimicrobial activity and antiproliferative capacity of EZPC were related to both its high anthocyanin content and anthocyanin composition (cyanidin derivatives especially). It is for the first time that the composition, antimicrobial activity, and antiproliferative capacity of EZPC were evaluated.     

紫玉米芯花青素的超声波辅助提取及喷雾干燥的工艺优化

以紫玉米芯为原料,利用响应面实验优化花青素的超声波辅助提取工艺,并将获得的花青素冻干粉添加麦芽糊精,后经喷雾干燥制成花青素粉。响应面实验结果表明,最佳提取条件为:料液比为1∶13(g/m L)、提取温度为41℃、水浴提取时间为31 min、超声提取时间为20 min,在此条件下,得到花青素提取量为(4.623±0.021)mg/g,提取率为94.8%。花青素提取液添加麦芽糊精,经喷雾干燥工艺制成花青素粉,在进风温度为150℃、花青素冻干粉与麦芽糊精质量比为1∶1、固形物浓度为15%时,得到的花青素粉包埋率为86.7%,水分含量为4.8%。本实验得到了紫玉米芯花青素超声辅助提取和花青素粉制备的最佳工艺条件,为紫玉米芯的开发利用提供了参考依据。      

Pressurized acidified water extraction of black carrot [<Emphasis Type="Italic">Daucus carota</Emphasis> ssp. <Emphasis Type="Italic">sativus</Emphasis> var. <Emphasis Type="Italic">atrorubens</Emphasis> Alef.] anthocyanins

The anthocyanins present in black carrot were extracted with pressurized water acidified with sulfuric, citric and lactic acids. Anthocyanin degradation became significant above 100 °C and there was no improvement when extraction pressure was increased to 100 bar. Therefore, the extraction from black carrot was carried out at temperatures 50, 75 and 100 °C under 50 bar pressure. The extraction efficiencies in terms of acylated and non-acylated anthocyanins were comparable for all three acids used to acidify water at 50 °C, while similar results were observed at 75 °C for both citric and lactic acids. Water acidified with lactic acid showed significantly higher extraction efficiency at 100 °C compared to water acidified with sulfuric and citric acids. Highest degree of polymerization together with increasing degree of browning was observed within extracts when sulfuric acid was used. On the other hand, when organic acids were used to acidify water, a higher extraction efficiency of anthocyanins, accompanied with a relatively low polymerization and browning was observed, with lactic acid giving the best results.     

Optimization of a process for enzyme-assisted pigment extraction from grape (<Emphasis Type="Italic">Vitis vinifera</Emphasis> L.) pomace

A process for enzyme-assisted extraction of polyphenols from grape pomace was developed on laboratory and pilot-plant scale. After resuspending grape pomace in water, the skins were ground and the resulting mash was pasteurized to inactivate the deteriorative enzymes responsible for polyphenol degradation, and then pre-extracted with hot water. Subsequently, cell wall polysaccharides were hydrolyzed. The extract was separated from the solid residue by pressing, and finally spray dried. Before scaling-up, enzymatic hydrolysis was optimized on laboratory scale using a D-optimal design and analyzed by response surface methodology. A mixture of pectinolytic and cellulolytic enzyme preparations (ratio 2:1) yielded the highest amounts of phenolic compounds after 2 h of treatment, applying a dosage of 4,500 mg/kg (based on dry matter) at T = 40 °C and pH 4.0. Aqueous pre-extraction of the pomace followed by enzymatic treatment resulted in significantly improved extraction yields reaching 91.9, 92.4, and 63.6% for phenolic acids, non-anthocyanin flavonoids and anthocyanins, respectively. As the yields obtained were comparable to those from sulfite-assisted extraction, this process can be considered a suitable alternative to the application of sulfite.     

Effect of glasswort (<Emphasis Type="Italic">Salicornia herbacea</Emphasis> L.) and rice (<Emphasis Type="Italic">oryza sativa</Emphasis> L.) on quality of <Emphasis Type="Italic">Ganjang</Emphasis> (Korean Soy Sauce)

Four types of meju were made from 100%(w/w) defatted soybean (DFS), a mixture of 80%(w/w) defatted soybean, and 20%(w/w) glasswort (DFS-G), a mixture of 80%(w/w) defatted soybean and 20%(w/w) rice (DFS-R), and a mixture of 60%(w/w) defatted soybean, 20%(w/w) glasswort, and 20%(w/w) rice (DFS-GR). Four types of Korean traditional soy sauce were prepared from the 4 types of meju. Mineral and antioxidant contents in the soy sauce made of DFS-G and DFS-GR were significantly higher than others. Citric, malic, succinic, lactic, and pyroglutamic acid contents in soy sauce made of DFS-R and DFS-GR were 1.3–1.5 times higher than others. Total nitrogen and free amino acid contents in soy sauce were correlated with DFS concentration in the meju. The bacterial community in the non-fermented meju-making ingredients was replaced largely by Bacillus sp. in the fermented meju. The use of glasswort and rice in the meju-making process did not alter the bacterial community responsible for the fermentation of meju.     

Estrogenic effects of various extracts from <Emphasis Type="Italic">Chamdanggui</Emphasis> (<Emphasis Type="Italic">Angelica gigas</Emphasis> Nakai) and <Emphasis Type="Italic">sogdan</Emphasis> (<Emphasis Type="Italic">Phlomis umbrosa</Emphasis> Turcz)

The various extracts from chamdanggui (Angelica gigas Nakai) and sogdan (Phlomis umbrosa Turcz) were evaluated for estrogenic activity and characterized according to HPLC profile. Chamdanggui and sogdan were individually extracted with 4 solvents (hot water, 70% ethanol, n-butanol, and dichloromethane) of differing polarities. Estrogenic activity was determined by E-screen using an estrogen-dependent MCF-7 BUS cell. Although almost all extracts showed estrogenic effects in a concentrationdependent manner, the hot water extract from chamdanggui (250 μg/mL) had the higher effect (138%). Among 90 fractions using HPLC separation of the hot water extract from chamdanggui, fraction 21 and 28 produced the highest estrogenic effects of 178 and 163% at 10 μg/mL, respectively. The results imply that the hot water extract from chamdanggui could be useful as an alternative hormone replacement therapy.     

Optimization for encapsulation of green tea (<Emphasis Type="Italic">Camellia</Emphasis><Emphasis Type="Italic">sinensis</Emphasis> L.) extract by spray drying technology

Green tea has been credited with providing a wide variety of health benefits like higher total antioxidant, cancer prevention, and anti-irritant etc. Microencapsulation technology is used to prevent antioxidant loss during processing which involves entrapment of active material into carrier material. The experiments were designed using response surface methodology based on three level two factor (green tea extract, 10–25 % and drying inlet air temperature, 120, 130 and 140°C) central composite design. The feed emulsion was prepared with green tea extract as core material and 40 % maltodextrin concentration as wall material with the ratio of core to wall (1:2) and it was fed into the spray dryer at varied drying inlet air temperature to get encapsulated green tea extract powder. The quality characteristics were analysed such as moisture content, total antioxidant activity and total phenolic content and the process conditions were optimized using desirability function methodology. At optimum spray drying condition moisture content, total antioxidant activity and total phenolic content were found to be 3.1 % w.b., 72.91 % free radical scavenging activity by DPPH method, 57.81 mg/g of dry matter, expressed as gallic acid equivalent respectively with desirability value of 0.92.     

Effect of Ferulic Acid on the Formation of Pyranoanthocyanins from Purple Corn (Zea mays L.) Cob in a Model System and Their Effects on Color

The stability enhancing effect of ferulic acid on anthocyanins from purple corn cob was investigated in a model system. The addition of ferulic acid provided color-enhancing and stabilizing effects on purple corn cob during storage and heating. These effects were observed through changes in spectrophotometric and CIE L*a*b* color space parameters. In test samples enhanced with ferulic acid, high-performance liquid chromatography–mass spectrometry detected and identified three new anthocyanin-derived pigments, cyanidin-3-glucoside-vinylguaiacol, pelargonidin-3-glucoside-vinylguaiacol, and peonidin-3-glucoside-vinylguaiacol, with respective m/z values of 595, 579, and 609.     

Tyramine production of technological important strains of <Emphasis Type="Italic">Lactobacillus</Emphasis>, <Emphasis Type="Italic">Lactococcus</Emphasis> and <Emphasis Type="Italic">Streptococcus</Emphasis>

The aim of this paper was to study the biogenic amines (histamine, tyramine, putrescine, cadaverine, agmatine, spermine and spermidine) production of selected technological important lactic acid bacteria (strains of the genera Lactococcus, Lactobacillus and Streptococcus). Three methods (ion-exchange chromatography (IEC), PCR and cultivation method with pH indicator) were used. Within the 39 strains of lactic acid bacteria tested, the production of tyramine (formed by tyrosine decarboxylase) was detected in eight strains (3 strains of Lactococcus lactis subsp. lactis, three strains of Lactococcus lactis subsp. cremoris, 1 strain of Streptococcus thermophilus and 1 strain of Lactobacillus delbrueckii subsp. bulgaricus). The other tested biogenic amines were not detected. Cultivation in decarboxylation broth seems to be the least accurate method for the detection of biogenic amines due to enhanced risk of false-positive reactions. Therefore, in order to detect bacteria producing biogenic amines, the combination of PCR and chromatographic methods (e.g. IEC) can be recommended.     

Quantification of anthocyanins in black carrot extracts (<Emphasis Type="Italic">Daucus carota</Emphasis> ssp.<Emphasis Type="Italic"> sativus</Emphasis> var.<Emphasis Type="Italic"> atrorubens</Emphasis> Alef.) and evaluation of their color properties

Pigment composition of 15 black carrot cultivars (Daucus carota ssp. sativus var. atrorubens Alef.) was screened by HPLC-MS. Up to seven cyanidin glycosides, five of which were acylated with hydroxycinnamic and hydroxybenzoic acids, were identified and quantified in the roots by HPLC-DAD. Contents of individual compounds indicated great differences in the potential of anthocyanin accumulation both between different cultivars and carrots of the same cultivar. Total anthocyanin amounts ranged from 45.4 mg/kg dry matter to 17.4 g/kg dry matter. To the best of our knowledge, this is the first report on the quantification of individual anthocyanins in roots of different black carrot cultivars. The determination of color properties in the extracts under various pH conditions proved black carrot anthocyanins to be applicable as natural food colorants also for low-acid food commodities, whereas a considerable loss of color was noted under nearly neutral conditions. Additionally, relatively high saccharide contents were found in almost all cultivars which may be disadvantageous when coloring concentrates are produced from carrot roots.     

Polyphenol composition of peel and pulp of two Italian fresh fig fruits cultivars (<Emphasis Type="Italic">Ficus carica</Emphasis> L.)

An analytical study was carried out on phenols in two fig cultivars (Ficus carica L.), one black and one green. Fresh fruits were peeled and phenols were extracted separately from the peel and the pulp. The extracts were subjected to HPLC-DAD analysis, by monitoring at four wavelengths, 280, 316, 365 and 520 nm for catechins and benzoic acids, hydroxycinnamic acids, flavonols and anthocyanins, respectively. Results showed that phenols are concentrated almost exclusively in the peel, with the black cultivar having the highest content. In particular, the peel was rich in rutin, with amounts from 527 to 1,071 mg/kg (fresh basis) for green and black figs, respectively. The peel of black figs showed an appreciable content of cyanidin 3-O-rutinoside. The pulp of both green and black cultivars contained only cyanidin 3-O-rutinoside, while the cyanidin 3-O-glucoside was found only in the peel of the black figs. Chlorogenic acid and another cinnamic acid were detected in the peel of both cultivars, while benzoic acids and catechins were not present. Alessandra Del Caro and Antonio Piga contributed equally to this study.     

Optimization of recombinant <Emphasis Type="Italic">Zea mays</Emphasis> transglutaminase production and its influence on the functional properties of yogurt

The requirements for the production of optimized Zea mays transglutaminase (TGZo) using Pichia pastoris GS115 (pPIC9K-tgzo) were optimized in this study. Plackett–Burman design was used to screen variables that significantly influence TGZo production. Oleic acid, methanol, and loading volume were identified as the most significant parameters. Central composite design was employed to determine the optimal level of these three parameters for TGZo production. Results showed that 1078 mU/mL of TGZo activity and 7.6 mg/L of TGZo production were obtained under conditions of 0.07% oleic acid, 1.31% methanol, and 7.36% loading volume. To explore the functional characteristics of TGZo, it was used in yogurt. It was found that the addition of TGZo could produce yogurt with stronger acid gel and higher consistency, cohesiveness, index of viscosity, and apparent viscosity than the untreated product. Therefore, TGZo can be used as a substitute for microbial transglutaminase in the yogurt, even in the food industry.     

Biochemical characterization of esterase from soybean (<Emphasis Type="Italic">Glycine max</Emphasis> L.)

Esterases are enzymes that present good potential in industrial application, and soybean seed can represent an alternative source for this enzyme. The extraction and esterase activity of Brazilian soybean seeds (Glycine max L.) were evaluated. Esterase activity was found in both the germinated and non-germinated seeds at 2.90 and 1.70 U/mg, respectively, with a concentration in the powdered extract (freeze dried) of 100 mg/mL. The enzyme showed a preference for the hydrolysis of short chain fatty acids (120.02 U/mL) and optimum pH for activity was pH 8.0 with optimum temperatures of 40 and 80°C. The enzyme showed stability at 70°C showing 60% of residual activity and activity increased with the addition of the following salts: NaNO₃, K₂SO₄, and Na₂SO₄ in the reaction medium.     

Effects of suni-bug (<Emphasis Type="Italic">Eurygaster</Emphasis> spp.) damage on size distribution of durum wheat (<Emphasis Type="Italic">Triticum durum</Emphasis> L.) proteins

Wholemeal samples were obtained from five durum wheat cultivars at two different bug (Eurygaster spp.) damage levels (medium and high damage). The samples were incubated (60 and 120 min) and used in size exclusion high performance liquid chromatography (SE-HPLC) analyses. The results showed that the amount of larger polymeric protein (TP1) and smaller polymeric protein (TP2) obtained from total (sodium dodecyl sulfate soluble) proteins decreased significantly in the bug-damaged samples, while the amount of total larger monomeric proteins (TP3) increased. The polymeric/monomeric protein ratio of all cultivars decreased at 60 min of incubation with increasing damage level. For all cultivars, the ratio of unextractable polymeric protein (UPP%) significantly decreased at 60 min of incubation except cv. Diyarbakir. The results suggested that bug protease caused depolymerization and/or disaggregation of polymeric proteins to lower their average molecular size. The changes in protein structure as determined using SE-HPLC supported by the decreases in gluten content and gluten index values which decreased with suni-bug damage. Deteriorative effects of bug damage on durum wheat quality were found to be quite similar to those on bread wheats.     

Thermal inactivation kinetics of quality-related enzymes in cauliflower (<Emphasis Type="Italic">Brassica oleracea</Emphasis> var. <Emphasis Type="Italic">botrytis</Emphasis><Emphasis Type="Bold">)</Emphasis>

Thermal inactivation of quality-related enzymes in both cauliflower crude enzyme extracts and fresh tissue samples was studied in temperature range 50–100 °C. For crude enzyme extracts, several parameters, reaction rate constants (k) and activation energy (E _a) as well as decimal reduction time (D) and (z) values, were used to characterize the thermal stability. The rates of inactivation were found to follow first-order inactivation kinetics. Activation energies varied between 101.18 and 208.42 kJ mol⁻¹ with z values of 10.59–24.09 °C. The examined kinetics indicated that lipoxygenase was the most heat resistant followed by peroxidase, polyphenol oxidase, pectin methyl esterase and ascorbic acid oxidase. Furthermore, the obtained results from the blanched fresh tissues indicated that inactivation of lipoxygenase secured disappearing of any other enzyme activities. Therefore, this study recommends using lipoxygenase as an indicator enzyme to optimize the thermal treatments of cauliflower products.     

Ethanolic fermentation from red ginseng extract using <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> and <Emphasis Type="Italic">Saccharomyces carlsbergensis</Emphasis>

The pH of red ginseng extracts fermented with Saccharomyces cerevisiae and Saccharomyces carlsbergensis decreased rapidly during 3 days of fermentation, with no further significant change thereafter. After 20 days of fermentation, a relatively small difference remained in the acidity of extracts fermented with S. cerevisiae (0.54%) and S. carlsbergensis (0.58%). Reducing sugar in the S. cerevisiae and S. carlsbergensis extracts decreased from 258.6 to 45.4 and 43.2 mg/mL glucose equivalents, respectively; and ethanol contents increased from 1.5% at day 0 to 16.0 and 15.0%, respectively, at day 20. Ginsenosides Rb₁, Rb₂, Rc, Re, Rf, and Rg₁ decreased during the fermentation with S. cerevisiae, but Rd and Rg₃ increased by day 12. Ginsenosides Rb₁, Rb₂, Rc, Re, and Rg₁ decreased gradually in the extract with S. carlsbergensis, but Rd and Rg₃ were increased at day 6 and 9, respectively.     

In vivo study of antiallergenicity of ethanol extracts from <Emphasis Type="Italic">Sargassum tenerrimum</Emphasis>, <Emphasis Type="Italic">Sargassum cervicorne</Emphasis> and <Emphasis Type="Italic">Sargassum graminifolium turn</Emphasis>

Food allergy has becoming the serious threat in the world for which the search of an effective anti-allergic drug is the demand of time. Keeping in view of the potentiality of seaweeds, the ethanol extracts from Sargassum tenerrimum (ST), Sargassum cervicorne (SC), and Sargassum graminifolium turn (SG) have been studied in vivo for its antiallergenicity through passive cutaneous anaphylaxis (PCA) and active cutaneous anaphylaxis (ACA) in female BALB/c mice. Intraperitoneal administration of these ethanol extracts inhibit mouse PCA and ACA in a dose-dependent manner using ovalbumin (OVA) and shrimp allergen as triggering agents to induce allergenicity over mice. The extract of ST containing phlorotannin has been found most active over the suppression of PCA triggered by OVA and shrimp with IC₅₀ values of 25.64 and 40.98 mg/kg, respectively and an efficacy comparable to that of an anti-allergic drug disodiumcromoglycate. Similarly, ST inhibits ACA triggered by ova and shrimp allergen in the mouse, with 50% suppression at 25.5 and 43.53 mg/kg, respectively. The results presented here show that these extracts are active on the studied models among which ethanol extract of ST was the most potent, leading toward the promising development of a new class of anti-allergic drugs.     

Molecular diversity among natural populations of <Emphasis Type="Italic">Lactobacillus paracasei</Emphasis> and <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis>/<Emphasis Type="Italic">paraplantarum</Emphasis> strains isolated from autochthonous dairy products

The diversity of 87 Lactobacillus paracasei and Lactobacillus plantarum/paraplantarum strains, previously identified from different autochthonous dairy products, was investigated by phenotypic and genotypic approaches. The increased resolution obtained using phenotypic and genotypic characterization allowed the level of strain heterogeneity detection to be widened. Phenotypic diversity was evaluated by studying biochemical characteristics of technological interest, including antimicrobial and proteinase activities, resistance to nisin, aggregation ability, production of exopolysaccharides, acetoin and diacetyl, citrate utilization, and antibiotic susceptibility. Genotypic diversity was generally evaluated by PCR amplification of repetitive bacterial DNA element fingerprinting using the (GTG)₅ primer [(GTG)₅-PCR]. Moreover, in cases where strains were not discriminated by (GTG)₅-PCR combined with phenotypic analysis, pulsed-field gel electrophoresis (PFGE) analysis was performed. The results indicate that L. plantarum/paraplantarum and L. paracasei natural isolates from artisanal dairy products are a gold mine in terms of diversity of strains and could be potentially interesting to dairy companies for the formulation of functional starter cultures in the production of innovative foods.