Loss of rutin and antioxidant activity of asparagus juice caused by a pectolytic enzyme preparation from Aspergillus niger

We found that a commercial pectolytic enzyme preparation from Aspergillus niger (pectinase AN) contained laccase activity that decreased rutin content and antioxidant activity of asparagus juice. This research investigated the effects of pH, temperature, and concentration of pectinase AN on pectinase AN’s laccase activity to decrease rutin content and antioxidant activity of asparagus juice. Asparagus juice was incubated with pectinase AN at different pHs (3.2, 4.5 and 5.8), temperatures (25, 37, and 50 °C) and enzyme concentrations (0.1%, 0.5% and 1%). Rutin content and antioxidant activity of samples was determined by HPLC and 2,2′-diphenyl-1-picrylhydrazyl (DPPH) free radical method, respectively. The rate of loss of rutin and antioxidant activity of asparagus juice was smaller at pH 3.2 than at pH 4.5 and pH 5.8, smaller for 0.1% pectinase AN than 0.5% and 1% pectinase AN. The rate of loss of rutin of asparagus juice was greater at 25 °C than at the other two temperatures. Pectinase AN can decrease rutin content and antioxidant activity of asparagus juice at the selected conditions. But rutin content and antioxidant activity of asparagus juice produced using pectinase AN could be less decreased at pH 3.2 and 0.1% of enzyme with less than 2 h of incubation time. This information was helpful for juice industry to produce juices with high antioxidant activity using pectinase AN.     

Physiochemical properties and kinetics of glucoamylase produced from deoxy-d-glucose resistant mutant of Aspergillus niger for soluble starch hydrolysis

Glucoamylases (GAs) from a wild and a deoxy-d-glucose-resistant mutant of a locally isolated Aspergillus niger were purified to apparent homogeneity. The subunit molecular mass estimated by SDS–PAGE was 93 kDa for both strains, while the molecular masses determined by MALDI-TOF for wild and mutant GAs were 72.876 and 72.063 kDa, respectively. The monomeric nature of the enzymes was confirmed through activity staining. Significant improvement was observed in the kinetic properties of the mutant GA relative to the wild type enzyme. Kinetic constants of starch hydrolysis for A. niger parent and mutant GAs calculated on the basis of molecular masses determined through MALDI-TOF were as follows: k_cat = 343 and 727 s⁻¹, K_m = 0.25 and 0.16 mg mL⁻¹, k_cat/K_m (specificity constant) = 1374 and 4510 mg mL⁻¹ s⁻¹, respectively. Thermodynamic parameters for soluble starch hydrolysis also suggested that mutant GA was more efficient compared to the parent enzyme.     

Immobilization of naringinase from Aspergillus niger CECT 2088 in poly(vinyl alcohol) cryogels for the debittering of juices

Naringinase, induced from Aspergillus niger CECT 2088 cultures, was immobilized into a polymeric matrix consisting of poly(vinyl alcohol) (PVA) hydrogel, cryostructured in liquid nitrogen, to obtain biocatalytically active beads. The effects of matrix concentration, enzyme load and pH on immobilization efficiency were studied. Between 95% and 108% of the added naringinase was actively entrapped in PVA cryogel, depending on the conditions of immobilization used. The optimal conditions were: 8% (w/v) PVA at pH 7 and 1.6–3.7 U ml⁻¹ of enzyme load. The pH/activity profiles revealed no change in terms of shape or optimum pH (4.5) upon immobilization of naringinase. However, the optimum temperature was shifted from 60 °C to 70 °C and the activation energy of reaction, E_a, was decreased from 8.09 kJ mol⁻¹ to 6.36 kJ mol⁻¹ by immobilization. The entrapped naringinase could be reused through six cycles (runs of 24 h at 20 °C), retaining 36% efficacy for the hydrolysis of naringin in simulated juice.     

Inhibitory effect of the essential oil of Curcuma longa L. and curcumin on aflatoxin production by Aspergillus flavus Link

Aflatoxins are highly toxic, mutagenic, teratogenic and carcinogenic mycotoxins. Consumption of aflatoxin-contaminated food and commodities poses serious hazards to the health of humans and animals. Turmeric, Curcuma longa L., is a native plant of Southeast Asia and has antimicrobial, antioxidant and antifungal properties. This paper reports the antiaflatoxigenic activities of the essential oil of C. longa and curcumin. The medium tests were prepared with the oil of C. longa, and the curcumin standard at concentrations varied from 0.01% to 5.0%. All doses of the essential oil of the plant and the curcumin standard interfered with mycotoxin production. Both the essential oil and curcumin significantly inhibited the production of aflatoxins; the 0.5% level had a greater than 96% inhibitory effect. The levels of aflatoxin B₁ (AFB₁) production were 1.0 and 42.7 μg/mL, respectively, for the samples treated with the essential oil of C. longa L. and curcumin at a concentration of 0.5%.     

Experimental design and response surface modeling applied for the optimisation of pectin hydrolysis by enzymes from A. niger CECT 2088

Optimisation of pectin hydrolysis using pectolytic enzymes produced by Aspergillus niger CECT 2088 was carried out. The effect of enzyme concentration (0.018–0.072%, w/v), substrate concentration (0.004–0.896%, w/v), pH (4.49–5.91), temperature (32.2–67.8 °C) and reaction time (18.2–71.8 min) on the enzymatic process was studied. The experiments were arranged according to a central composite statistical design. Response surface methodology (RSM) was used to assess factor interactions and empirical models regarding four product response variables (i.e., reactor conversion, reducing sugar concentration, endopectolytic productivity and enzymatic depolymerization productivity). Multi-response optimisation was also performed on the reactor and endopectolytic productivity data set of the factorial design. The highest reactor conversion (61%) and endopectolytic productivity (7.2 cSt mg⁻¹ ml⁻¹) were achieved with 1 h reaction time at 46 °C and pH 4.8 at a substrate/enzyme ratio of 11.6.     

Effect of Capsicum carotenoids on growth and aflatoxins production by Aspergillus flavus isolated from paprika and chilli

The aim of this study was to determine the effect of a carotenoid mixture (Capsantal FS-30-NT), containing capsanthin and capsorubin, on growth and aflatoxins (AF) production of AF-producing Aspergillus flavus isolates.     

Optimisation of antioxidants extraction from soybeans fermented by Aspergillus oryzae

The extraction of antioxidant compounds from soybeans fermented with Aspergillusoryzae was optimised using a factorial design. A kinetic study of the total phenolic production and DPPH radical scavenging activity was first performed at the points selected in the factorial design. In both cases, the experimental profiles were fitted to a modified first-order kinetic model. To investigate the combined effects of temperature and solvent concentration on the extraction, the parameters obtained from the fitted kinetic models were used as response variables in a rotatable second-order design with quintuple replications in the centre of the experimental domain. The results obtained indicate that temperature had the most significant effect. The response surfaces show a maximum in the experimental domain studied. The optimum conditions for the extraction of total phenolic content were 65.3 °C and 73.1% ethanol, in which 56.2 mg of GAE/g were predicted. A scavenging activity of 81.6% DPPH radical was predicted at the optimum conditions of 61.6 °C and 60% ethanol.     

Advantages of a proteolytic extract by Aspergillus oryzae from fish flour over a commercial proteolytic preparation

Proteolytic extract (CPE) was produced by Aspergillus oryzae 2095 under solid state fermentation using a mix of fish flour with polyurethane foam (70:30, w/w) of particle size of 0.5 mm. The proteolytic activity from CPE was compared to a commercial protease (Flavourzyme 500 MG^®). The maximal activity for both extracts was found at pH 8 and 50 °C. The half-lives of CPE and Flavourzyme 500 MG^® were 52 and 25 min at 50 °C, respectively. Furthermore, the hydrolytic activity for both extracts was tested on muscle of giant sea bass (Epinephelus morio), CPE produced a higher degree of hydrolysis (DH) than Flavourzyme 500 MG^® (22.2 and 9.1%, respectively) under optimal experimental conditions for each extract.     

Activity of essential oil and its major compound, 1,8-cineole, from Eucalyptus globulus Labill., against the storage fungi Aspergillus flavus Link and Aspergillus parasiticus Speare

The essential oil from leaves of Eucalyptus globulus obtained by hydrodistillation, as well as its major compound 1,8-cineole, identified by gas chromatography coupled with a mass selective detector, were evaluated for their effectiveness against the storage fungi Aspergillus flavus and Aspergillus parasiticus. The evaluation was performed by compound dissolution in yeast extract sucrose (YES) medium and exposure to headspace volatiles. Complete fungal growth inhibition of both species was achieved with the essential oil by contact and volatile assays. Volatile exposure showed total inhibition at the lower level tested of 500 μL. The 1,8-cineole tested alone showed partial inhibition only at the highest level of 1.3492 μL. Aflatoxin B₁ production was reduced in headspace volatile assays and partial inhibition was observed at the 200 μL dose of the essential oil.     

Effect of different temperatures and storage atmospheres on Coratina olive oil quality

Olives (Olea europaea cv. Coratina) used for oil production were stored for 30 days at three different temperatures and under different atmospheres (ambient temperature, 5 °C with a flux of humidified air, 5 °C with a flux of 3%O₂ + 5%CO₂). The olives were kept in jars used for fruit storage, each with a capacity for 1.5 kg of olives.     

Crude palm oil from interspecific hybrid Elaeis oleifera × Elaeis guineensis: Fatty acid regiodistribution and molecular species of glycerides

The composition and structure of triacylglycerols (TAGs) and partial glycerides of crude palm oil obtained from interspecific hybrid Elaeis oleifera × Elaeis guineensis, grown in Colombia, were fully characterised and compared to data obtained by analysing crude African palm oil. Hybridisation appears to substantially modify the biosynthesis of fatty acids (FAs) rather than their assembly in TAGs. In fact, total FAs analysis showed significant differences between these two types of oil, with hybrid palm oil having a higher percentage of oleic acid (54.6 ± 1.0 vs 41.4 ± 0.3), together with a lower saturated fatty acid content (33.5 ± 0.5 vs 47.3 ± 0.1), while the percentage of essential fatty acid, linoleic acid, does not undergo significant changes. Furthermore, 34 TAG types were identified, with no qualitative differences between African and E. guineensis × E. oleifera hybrid palm oil samples. Short and medium chain FAs (8:0, 10:0, 12:0, 14:0) were utilised, together, to build a restricted number of TAG molecular species. Oil samples from the E. guineensis × E. oleifera hybrid showed higher contents of monosaturated TAGs (47.5–51.0% vs 36.7–37.1%) and triunsaturated TAGs (15.5–15.6% vs 5.2–5.4%). The sn-2 position of TAGs in hybrid palm oil was shown to be predominantly esterified with oleic acid (64.7–66.0 mol% vs 55.1–58.2 mol% in African palm oil) with only 10–15% of total palmitic acid and 6–20% of stearic acid acylated in the secondary position. The total amount of diacylglycerols (DAGs) was in agreement with the values of free acidity; DAG types found were in agreement with the representativeness of different TAG species.     

Biotransformation of phenolics (isoflavones,flavanols and phenolic acids) during the fermentation of cheonggukjang by Bacillus pumilus HY1

Changes in β-glycosidase, esterase activities, isoflavone, flavanols and phenolic acid during the fermentation of Korean whole soybean fermented food cheonggukjang by Bacillus pumilus HY1 were investigated. The levels of aglycones, flavanols and gallic acid increased, while the β-glucosidase activity, esterase activity, glycosides content (except for acetylglycosides) and flavanol gallates decreased. Total isoflavone content slightly decreased after 60 h of fermentation, while total flavanol and phenolic acid content increased. The highest levels of daidzein (aglycone type) and acetyldaidzin (glycoside type) were recorded after 48 h of fermentation. The levels of catechin, epicatechin and gallic acid also increased during fermentation. However, total contents of glycosides, malonylglycosides and flavanol gallates decreased by about 80%, 90% and 60% during 60 h of fermentation, respectively. In addition, total phenolic content increased markedly during fermentation, while levels of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity increased. Hence, it would be beneficial for the food industry if components of cheonggukjang could be separated and developed into functional products.     

Effects of Lycium barbarum extract on production and immunomodulatory activity of the extracellular polysaccharopeptides from submerged fermentation culture of Coriolus versicolor

Polysaccharopeptides (PSPs) from Coriolus versicolor have been used as immunomodulatory and anticancer agents. However, most studies have concentrated on the mycelial PSPs and not those in the fermented broth. On the other hand, Lycium barbarum fruit has been used as a traditional Chinese herbal medicine for two millennia. Its extract contains various nutrients, minerals, and also polysaccharide–protein complexes, which are proven to be bioactive. Herein we report the effects of L. barbarum fruit extract on the mycelial growth and extracellular PSP (ePSP) production of C. versicolor LH1 by using a submerged fermentation process in 20 l fermenters. Fermentation production of C. versicolor biomass and its ePSP were augmented in the presence of L. barbarum extract. The ePSP such obtained differs from those obtained with normal culture medium in terms of simple sugar composition and protein content but shows similar overall chemical structures as analyzed by Fourier transformed infrared spectroscopy. Moreover, the ePSP from C. versicolor cultured with supplementary L. barbarum extract exhibits significant immunomodulatory activity as judged by its effects on the production of nitric oxide and several cytokines by murine RAW264.7 macrophages.     

Preparation of eicosapentaenoic acid concentrates from sardine oil by Bacillus circulans lipase

An extracellular lipase derived from Bacillus circulans, isolated from marine macroalga, Turbinaraia conoides, was used to prepare n-3 polyunsaturated fatty acid (PUFA) concentrates from sardine oil triglycerides. The enzyme was purified 132-fold with specific activity of 386 LU/mg. The purified lipase was able to enrich sardine oil with 37.7 ± 1.98% 20:5n-3 and 5.11 ± 0.14% 18:3n-3 in the triglyceride fraction after 3 h of hydrolysis. Lower hydrophobic constants of n-3 fatty acids (18:3n-3_logP = 5.65; 20:5n-3_logP = 5.85, respectively) than n-6 (20:4n-6_logP = 6.16) resulted in higher hydrolytic resistance of the former toward lipase, leading to their enrichment in the triglyceride fraction. Lipase-catalysed hydrolysis of sardine oil for 3 h, followed by urea complexation, provided free fatty acids containing 51.3 ± 4.65% 20:5n-3. The purified methyl ester of 20:5n-3 (68.29 ± 2.15%) from the urea concentrate was attained by chromatography on argentated neutral alumina.     

Influence of alcoholic fermentation process on antioxidant activity and phenolic levels from mulberries (Morus nigra L.)

The aim of the present study was to evaluate the profile of the phenolic constituents of Morus nigra fruits and their antioxidant activity (DPPH) and to compare their contents before and after fermentation. Antioxidant phenolics of black mulberry (M. nigra L.) samples grown in Galicia (NW Spain) were extracted with methanol/formic acid/water (MFW) and determined by high performance liquid chromatography (HPLC). Two major anthocyanins (cyanidin 3-glucoside and cyanidin 3-rutinoside) and two flavonols (quercetin 3-glucoside and rutin) were isolated, together with caffeic acid and other hydroxycinnamic and ellagic acid derivatives. Their chemical structures were identified by spectral analyses with diode array detection (DAD), but also with alkaline saponification and acid hydrolysis of the mulberry phenolics. Good correlations (r² = 0.6229) were observed among total flavonols contents and the IC₅₀ radical scavenging capacities of mulberry fruits. Anthocyanins are the major flavonoids present in mulberry. It would be expected that anthocyanins contribute significantly to their antioxidant activity; nevertheless, alcohol generated during fermentation may also contribute to antioxidant activity. Our results provide useful antioxidant nutritional information of fresh and fermented mulberry fruits.     

Effect of different fermentation parameters on l-lactic acid production from liquid distillery stillage

Expansion of lactic acid applications, predominantly for the preparation of biodegradable polymers increased the research interest for new, economically favourable production processes. Liquid stillage from bioethanol production can be an inexpensive, valuable source of nutrients for growth of lactic acid bacteria. Utilisation of residual biomass with spent fermentation media as a functional animal feed can greatly influence the process value and its ecological aspect. In this paper, the kinetics of lactic acid and biomass production on liquid stillage by Lactobacillus rhamnosus ATCC 7469 was studied. In addition, the impact of temperature, inoculum concentration, shaking and pH control by addition of CaCO₃ was evaluated. Maximal lactic acid yield of 73.4%, as well as high biomass production (3 × 10⁸ CFU ml⁻¹) were achieved under selected conditions (41 °C, 5% (v/v) of inoculum, 1% (w/v) of CaCO₃, initial pH of 6.5 and shaking rate of 90 rpm). These results were achieved without supplementation of the stillage with nitrogen or mineral sources.     

Effect of nutritional and environmental conditions on the production of exo-polysaccharide of Agaricus brasiliensis by submerged fermentation and its antitumor activity

Mushrooms have become attractive as a functional food and as a source for the development of drugs and nutraceuticals. A. brasiliensis is considered as the best among them. There are several published works on the fruiting bodies of this mushroom, showing high antitumor activity. The mycelium polysaccharide and exo-polysaccharide (EPS) of this mushroom also demonstrated a strong antitumor action. However, there is little information available in the literature about the optimization of physical and chemical conditions for production of EPS by submerged fermentation (SmF). After initial screening from the five strains available in the LPB Culture Collection, A. brasiliensis LPB 03 was selected for EPS production in SmF. Studies on supplementation of a carbon source to the medium revealed that sucrose was most effective for EPS production. Yeast extract was the best for EPS among the inorganic and organic nitrogen sources tested. The factorial experiment demonstrated that a temperature of 30 °C and a pH of 6.1 were the best for the EPS production. Glucose 10 g/l, yeast extract 3 g/l, K₂HPO₄ 0.6 g/l and MgSO₄ 0.3 g/l were most suitable for the EPS production. Maximum EPS production was obtained in the static condition with manual agitation two times per day after a 1-week culture (382 mg/l), increasing by 78.62% more than that before optimization. In the bioreactor with aeration and agitation, the maximum EPS was produced at 321.2 mg/l. The EPS of A. brasiliensis produced in SmF showed strong inhibition against Sarcoma 180 in mice, reaching 72.19% inhibition compared with the control group. Furthermore, 50% of mice in the test group demonstrated total tumor regression.