Učinak hidrolizata glutena i njegovih frakcija dobivenih ultrafiltracijom na svojstva tijesta i kakvoću kruha

Two fractions (50-K and permeate) from a proteolytic hydrolysate (degree of hydrolysis, DH=3.8 %) of wheat gluten were separated using ultrafiltration (UF) membrane with molecular mass cut-off of 50 kDa. The effects of the wheat gluten hydrolysate (WGH) and its UF fractions on the mixing behaviour and viscoelastic properties of wheat dough were presented. The WGH and its UF fractions modified the mixing properties of dough. The addition of these fractions improved the viscoelastic characteristics of wheat dough. A significant (p<0.05) effect of 50-K fraction on these characteristics of wheat dough was observed. After adding these fractions, the bread was considered acceptable by the sensory panel. Also, 50-K fraction resulted in significant (p<0.05) increase in the crumb firmness, while the bread made with wheat flour with WGH and permeate (P) fraction showed softer crumbs compared to that of wheat flour. Moreover, these fractions had anti-staling properties for bread during storage. Hence, the wheat gluten hydrolysate and its UF fractions are the products with promising potential in the baking products.Odvojene su dvije frakcije (50-K i permeat) iz proteolitičkog hidrolizata glutena (stupanj hidrolize, DH=3,8 %) pomoću ultrafiltracijske (UF) membrane sa segmentima molarne mase od 50 kDa. Prikazan je učinak hidrolizata glutena i njegovih frakcija dobivenih ultrafiltracijom na dizanje tijesta i njegovu viskoznost i elastičnost tijekom miješanja. Utvrđeno je da se dodatkom hidrolizata glutena i njegovih frakcija mijenjaju svojstva tijesta pri miješanju, te poboljšavaju viskoznost i elastičnost tijesta. Uočen je značajan učinak (p<0,05) dodatka frakcije 50-K na ta svojstva tijesta, te znatno (p<0,05) povećanje čvrstoće mrvica, a takav je kruh imao zadovoljavajuće karakteristike, što je potvrdila i ocjenjivačka komisija. Kruh od pšeničnog brašna s dodatkom hidrolizata glutena i frakcije permeata dao je mekše mrvice od kruha napravljenog samo od pšeničnog brašna. Osim toga, dodatak tih frakcija spriječio je stvaranje plijesni na kruhu tijekom skladištenja. Stoga hidrolizat glutena i njegove frakcije dobivene ultrafiltracijom imaju velike mogućnosti primjene u pekarskim proizvodima

Spektrofotometrijska metoda određivanja triptofana iz hidrolizata proteina

A novel spectrophotometric method for determination of tryptophan content in protein hydrolysates has been developed. The reagent used is diphenylamine sulphonate which is oxidised to diphenylbenzidine sulphonic acid after reacting with sodium nitrite in the sulphuric acid medium. The unstable oxidation product reacts quickly with sodium nitrite to produce a diazotized intermediate. When the diazotized intermediate is coupled with tryptophan, a pink colour product is developed, which is stable for at least 1 h at the ambient temperature. This coloured product has the absorption maximum at 522 nm and the molar absorptivity is 8900 L/(mol·cm). Beer’s law is obeyed in the range of 0.30–12 mg/mL. The method is applied for the analysis of tryptophan content in grass carp protein hydrolysates. Moreover, it is compared with the reversed-phase high-performance liquid chromatography analysis. There is no significant (p<0.05) difference between the two results. The method is simple, rapid and accurate compared to the previous methods.Razvijena je nova metoda određivanja udjela triptofana u hidrolizatima proteina. Kao reagens upotrijebljen je difenilamin-sulfonat, koji reakcijom s natrijevim nitritom u mediju sa sulfatnom kiselinom oksidira u difenilbenzidin-sulfonsku kiselinu. Nestabilan proizvod oksidacije brzo reagira s natrijevim nitritom te nastaje diazotizirani intermedijer. Spajanjem diazotiziranog intermedijera s triptofanom nastaje produkt ružičaste boje koji je barem 1 sat stabilan na sobnoj temperaturi. Taj obojeni produkt ima apsorpcijski maksimum pri 522 nm i molarni apsorpcijski koeficijent od 8900 L/(mol·cm), te se ponaša u skladu s Beerovim zakonom u rasponu od 0,30 do 12 µg/mL. Ova se metoda primjenjuje za analizu udjela triptofana u hidrolizatima proteina amura, te je uspoređena s visokotlačnom tekućinskom kromatografijom obrnutih faza (RP-HPLC). Nije primijećena značajna razlika (p<0,05) između rezultata tih dviju metoda. Spektrofotometrijska metoda određivanja triptofana je jednostavnija, brža i preciznija od ranije korištenih metoda

Učinak hidrolizata glutena i njegovih frakcija dobivenih ultrafiltracijom na svojstva tijesta i kakvoću kruha

Two fractions (50-K and permeate) from a proteolytic hydrolysate (degree of hydrolysis, DH=3.8 %) of wheat gluten were separated using ultrafiltration (UF) membrane with molecular mass cut-off of 50 kDa. The effects of the wheat gluten hydrolysate (WGH) and its UF fractions on the mixing behaviour and viscoelastic properties of wheat dough were presented. The WGH and its UF fractions modified the mixing properties of dough. The addition of these fractions improved the viscoelastic characteristics of wheat dough. A significant (p<0.05) effect of 50-K fraction on these characteristics of wheat dough was observed. After adding these fractions, the bread was considered acceptable by the sensory panel. Also, 50-K fraction resulted in significant (p<0.05) increase in the crumb firmness, while the bread made with wheat flour with WGH and permeate (P) fraction showed softer crumbs compared to that of wheat flour. Moreover, these fractions had anti-staling properties for bread during storage. Hence, the wheat gluten hydrolysate and its UF fractions are the products with promising potential in the baking products.Odvojene su dvije frakcije (50-K i permeat) iz proteolitičkog hidrolizata glutena (stupanj hidrolize, DH=3,8 %) pomoću ultrafiltracijske (UF) membrane sa segmentima molarne mase od 50 kDa. Prikazan je učinak hidrolizata glutena i njegovih frakcija dobivenih ultrafiltracijom na dizanje tijesta i njegovu viskoznost i elastičnost tijekom miješanja. Utvrđeno je da se dodatkom hidrolizata glutena i njegovih frakcija mijenjaju svojstva tijesta pri miješanju, te poboljšavaju viskoznost i elastičnost tijesta. Uočen je značajan učinak (p<0,05) dodatka frakcije 50-K na ta svojstva tijesta, te znatno (p<0,05) povećanje čvrstoće mrvica, a takav je kruh imao zadovoljavajuće karakteristike, što je potvrdila i ocjenjivačka komisija. Kruh od pšeničnog brašna s dodatkom hidrolizata glutena i frakcije permeata dao je mekše mrvice od kruha napravljenog samo od pšeničnog brašna. Osim toga, dodatak tih frakcija spriječio je stvaranje plijesni na kruhu tijekom skladištenja. Stoga hidrolizat glutena i njegove frakcije dobivene ultrafiltracijom imaju velike mogućnosti primjene u pekarskim proizvodima

Effect of oxidation on the gel properties of porcine myofibrillar proteins and their binding abilities with selected flavour compounds

In this work, the effect of oxidation induced by hydroxyl radicals on the binding abilities of myofibrillar protein (MP) gels to aldehydes and ketones and their relationship with MP gel properties were investigated. Mild oxidation (0-0.2 mM H2O2) could induce partial unfolding of MP, thus slightly increasing the salt solubility of MP and enhancing the hardness of MP gels. MP suffering a higher oxidative attack could undergo a reduction in water-holding capacity, with increased mobility of water in MP gels. Oxidation could make MP gel more disordered. The ability of oxidised MP gels to bind to flavours decreased as the carbon chain length of the flavour compound increased. MP oxidation only significantly affected the binding of MP gels to hexanal, heptanal, and 2-octanone, while other flavour compounds were not affected

Artificial Neural Network for Production of Antioxidant Peptides Derived from Bighead Carp Muscles with Alcalase

Kontrolirani enzimski modificirani proteini koriste se kao dobri izvori bioaktivnih sastojaka proteina, a hidrolizati iz mišića pjegavog šarana mogu se upotrijebiti kao antioksidansi u kontroliranim uvjetima. Antioksidativna sposobnost je procijenjena prema sposobnosti uklanjanja slobodnih radikala DPPH × , OH × i O2 × . Zbog robusnosti, tolerancije na greške, velike brzine računanja i mogućnosti samoučenja, umjetna neuronska mreža može se upotrijebiti za simulaciju modela i optimiranje varijabli hidrolize: pH-vrijednosti, temperature, vremena hidrolize, omjera mišića i vode, te omjera enzima i supstrata (E/S) za proizvodnju antioksidativnih peptida. Postignuti su optimalni uvjeti za postizanje maksimalne antioksidativne sposobnosti. Hidrolizati koji su učinkovito uklonili DPPH×, OH× i O2 × radikale hidrolizirani su nakon 4,8 sata pri aktivnosti alkalaze od 4,8 AU/kg i omjeru mišića/vode od 1:1,9; za 6 sati pri 3,84 AU/kg i omjeru od 1:1,4; te za 4,3 sata pri 4,8 AU/kg i omjeru mišića/vode od 1:1; pri pH-vrijednosti od 7,5 i 60 °C. Ovo je istraživanje potvrdilo da se umjetna neuronska mreža može upotrijebiti za simulaciju reakcije te predviđanje uvjeta hidrolize pri kojima hidrolizati pokazuju najveću sposobnost uklanjanja slobodnih radikala DPPH × , OH × i O2 × .Controlled enzymatic modification proteins are currently being used as good sources of bioactive protein ingredients, and hydrolysates derived from bighead carp muscles may serve as antioxidants through the control of the processing-related parameters. The antioxidant ability was evaluated with regard to the scavenging effect on free radical DPPH·, OH· and O2 ·–. Due to the robustness, fault tolerance, high computational speed and self--learning ability, artificial neural network (ANN) can be employed to build a predictive model for hydrolysis and optimize the hydrolysis variables: pH, temperature, hydrolysis time, muscle/water ratio and enzyme/substrate ratio (E/S) for the production of antioxidant peptides. Optimum conditions to achieve the maximum antioxidant ability were obtained. The hydrolysates, which scavenged most effectively the DPPH·, OH· and O2 ·–, were hydrolyzed for 4.8 h with an activity of alcalase of 4.8 AU/kg, for 6 h with 3.84 AU/kg and for 4.3 h with 4.8 AU/kg, at pH=7.5 and 60 °C. Their respective muscle/water ratio was 1:1.9, 1:1.4 and 1:1. The present study confirmed that ANN could be used to simulate the hydrolysis process and predict hydrolysis conditions under which the hydrolysates could show the most effective scavenging ability on DPPH·, OH· and O2 ·–

Effect of Metal-Binding Antimicrobial Peptide SIF4 on Topoisomerases Activity and Intracellular Nucleic Acid Biosynthesis in Escherichia coli

To systematically elucidate how metal-binding antimicrobial peptide SIF4 exerts its antimicrobial activity by targeting DNA topoisomerase without destroying the cytoplasmic membrane, Escherichia coli was used as a model strain to investigate the binding mode of SIF4 with its genomic DNA and the impact of SIF4 on DNA topoisomerase I and II activities and intracellular nucleic acid biosynthesis. Results showed that SIF4 could bind to genomic DNA in a manner similar to ethidium bromide (EB) intercalation with strong inhibitory effect on topoisomerase I but weak effect on topoisomerase II, and catalyzed RNA transcription to exert antimicrobial activity by interfering with the unwinding of negative DNA supercoils and RNA polymerase binding. It was also found that the biosynthesis of intracellular DNA and RNA was inhibited to different degrees after 12 h treatment with SIF4, which exhibited a good dose-effect relationship. There was no significant difference in the amounts of intracellular DNA and RNA between the 1/2 minimum inhibitory concentration (MIC) group and the control group (P > 0.05), but there was a significant difference between the MIC and 2 MIC groups and the control group (P < 0.05). Our results may provide theoretical support for the application of SIF4 in the biocontrol of foodborne E. coli

Survey of the transcriptome of Aspergillus oryzae via massively parallel mRNA sequencing

Aspergillus oryzae, an important filamentous fungus used in food fermentation and the enzyme industry, has been shown through genome sequencing and various other tools to have prominent features in its genomic composition. However, the functional complexity of the A. oryzae transcriptome has not yet been fully elucidated. Here, we applied direct high-throughput paired-end RNA-sequencing (RNA-Seq) to the transcriptome of A. oryzae under four different culture conditions. With the high resolution and sensitivity afforded by RNA-Seq, we were able to identify a substantial number of novel transcripts, new exons, untranslated regions, alternative upstream initiation codons and upstream open reading frames, which provide remarkable insight into the A. oryzae transcriptome. We were also able to assess the alternative mRNA isoforms in A. oryzae and found a large number of genes undergoing alternative splicing. Many genes and pathways that might be involved in higher levels of protein production in solid-state culture than in liquid culture were identified by comparing gene expression levels between different cultures. Our analysis indicated that the transcriptome of A. oryzae is much more complex than previously anticipated, and these results may provide a blueprint for further study of the A. oryzae transcriptome

Theragra chalcogramma Hydrolysate, Rich in Gly-Leu-Pro-Ser-Tyr-Thr, Alleviates Photoaging via Modulating Deposition of Collagen Fibers and Restoration of Extracellular Components Matrix in SD Rats

Excessive exposure of the skin to ultraviolet irradiation induces skin photoaging, which seriously deteriorates the barrier functions of skin tissue, and even causes skin damages and diseases. Recently, dietary supplements from marine sources have been found to be useful in modulating skin functions and can be used to alleviate photoaging. Herein, the low-molecular-weight hydrolysates with a photoaging-protection effect were prepared by enzymatic hydrolysis from Theragra chalcogramma (TCH), and the potential mechanism were subsequently explored. The results revealed that TCH desirably improved the barrier functions of photoaged skin and stimulated the deposition of ECM components Col I, Hyp, and HA in the dermal layer. Histologically, TCH reduced the epidermal hyperplasia and restored the impaired architectures in a dose-dependent manner. Meanwhile, the activity of matrix metalloproteinase-1 (MMP-1) in photoaging skin was inhibited, and the expression levels of elastin and fibrillin-1 were elevated accordingly after TCH administration, and the significant improvements were observed at high-dose level (p &lt; 0.05). Taken together, the efficacy of TCH against skin photoaging is highly associated with the regulation on ECM metabolism and the repairing of damaged mechanical structure

Effects of Wheat Gluten Hydrolysate and Its Ultrafiltration Fractions on Dough Properties and Bread Quality

Two fractions (50-K and permeate) from a proteolytic hydrolysate (degree of hydrolysis, DH=3.8 %) of wheat gluten were separated using ultrafiltration (UF) membrane with molecular mass cut-off of 50 kDa. The effects of the wheat gluten hydrolysate (WGH) and its UF fractions on the mixing behaviour and viscoelastic properties of wheat dough were presented. The WGH and its UF fractions modified the mixing properties of dough. The addition of these fractions improved the viscoelastic characteristics of wheat dough. A significant (p<0.05) effect of 50-K fraction on these characteristics of wheat dough was observed. After adding these fractions, the bread was considered acceptable by the sensory panel. Also, 50-K fraction resulted in significant (p<0.05) increase in the crumb firmness, while the bread made with wheat flour with WGH and permeate (P) fraction showed softer crumbs compared to that of wheat flour. Moreover, these fractions had anti-staling properties for bread during storage. Hence, the wheat gluten hydrolysate and its UF fractions are the products with promising potential in the baking products