Respiration by fruits and vegetables is vital action to generating the ATP needed for maintenance of cell viability, even after harvesting and as nutrients decompose. Therefore, respiration is strongly associated with qualitative deterioration during transportation and storage. Measurement and mathematical modeling of O2 uptake and CO2 production rates have been effective for evaluating the deterioration rate of horticultural products. ATP is produced by FOF1-ATP synthase through the transfer of electrons from ubiquinone to cytochrome c oxidase (COX) in plant cells. Although COX consumes a large amount of O2 taken into cells, oxidizing protons as the terminal enzyme in the classical electron transport chain, an alternative pathway involving an alternative oxidase has been discovered, which performs the same reaction in plant cells without producing ATP. Staining and light sensing have been employed to measure enzymatic activity and O2 consumption rate, respectively.
Date-tamarind fruit leathers with varied textural characteristics were prepared by drying a paste containing hydrocolloid (starch, pectin, dextrin or guar gum) and water at 70°C for 28, 42, 56, 70 and 84 h. Hardness, cohesiveness, adhesiveness, springiness, brittleness, resilience, gumminess and chewiness of the blank date-tamarind fruit leather (i.e., without any hydrocolloid) did not show any correlation with the moisture content ranges (29 − 41 g/100 g sample) used in the present study. Hardness and gumminess increased when hydrocolloids were added, while cohesiveness, resilience and springiness decreased. With the exception of dextrin all other hydrocolloids increased chewiness. Principal Component Analysis (PCA) identified 5 principal components (i.e., 5 factors: plasticity, elasticity, hydrocolloids’ concentration, resilience, cohesiveness) affecting the characteristics of each date-tamarind fruit leather. The cluster analysis identified 4 classes of the fruit leathers and bi-plot (i.e., including all products and their characteristics), generated through PCA, recognized these classes as hard-chewy, soft-springy, hard-fragile and soft-resilient leathers.
A rapid method for predicting total aflatoxin (aflatoxins B1, B2, G1, and G2) in nutmeg extract was developed using fluorescence fingerprint (FF) and partial least squares (PLS) regression. FF is also known as excitation-emission matrix, which is a series of fluorescence spectra acquired by scanning an excitation wavelength. Nutmeg extract was artificially spiked with an aflatoxin reagent. The FF of spiked nutmeg extract was measured with a fluorescence spectrometer. The FF data was preprocessed to remove signals not related to fluorescence. After preprocessing, 1428 out of 5041 fluorescence intensities remained. They were set as explanatory variables for PLS regression. Then, total aflatoxin concentration was set as the response variable. Eleven out of 21 samples were used as the calibration dataset; the remaining ten were used as the validation dataset. Three latent variables were used to develop the ideal PLS model by cross validation. R2 was 0.993 and SEC was 0.2 μg/L for the calibration dataset. Significant correlations were observed between the actual and predicted values for the validation dataset, with R2 of 0.773 and SEP of 1.0 μg/L. The PLS regression coefficient, which shows the degree of contribution of each wavelength to the model, indicated that the prediction was mainly based on the fluorescence of aflatoxin itself.
Rice straw stem was treated with subcritical water, ethanol, or a mixture at 170°C to 230°C. The yield, total carbohydrate content, UV-Vis absorption spectra, phenolic content, radical scavenging activity, and HPLC analysis of the extracts were determined. Higher stem extract yield and total carbohydrate content were achieved when the stem was treated using a subcritical ethanol/water mixture with high ethanol content and at the higher temperature. A maximum yield and total carbohydrate content of 0.387 ± 0.004 g/g-stem and 0.219 ± 0.021 g/g-stem, respectively, were achieved when the stem was treated with 50% (v/v) ethanol at 230°C. The extract obtained using 75% (v/v) ethanol at 230°C had the highest total phenolic content and radical scavenging activity of 45.2 ± 1.1 mg-gallic acid equiv./g-stem and 0.308 ± 0.022 mmol-vitamin C equiv./g-stem, respectively.
The freshness keeping effect of cardboard boxes with inner freshness keeping coating on the strawberries was studied. The strawberries came from Hangzhou Yuhang was used as the test object to investigate the effect of coating agents on the physical properties of strawberries, and response surface analysis was used to optimize the coating formula. Results show that the weight loss and cell membrane permeability of strawberries packaged in the cardboard boxes coated with hydrated silicon dioxide, KMnO4 and polylysine are less than that of strawberries packaged in conventional cardboard boxes, while the hardness of strawberries in coated cardboard boxes is higher than that of strawberries in conventional cardboard boxes, that is, cardboard boxes with inner freshness keeping coating have better effect. The best freshness keeping coating formula is: hydrated silicon dioxide: 71.97%; KMnO4: 0.136%; polylysine: 0.237%.
The ability of heated scallop-shell powder (HSSP) to disinfect Staphylococcus aureus biofilm was investigated. A biofilm of S. aureus NBRC 13276 was produced on a glass plate. Scallop-shell powder was exposed to heat treatment at 1000°C in air for 1 h, followed by immersion of the biofilm plate into the HSSP slurry. After treatment, the disinfection ability of the HSSP toward the biofilm was measured non-destructively and quantitatively using a conductometric assay. Disinfection efficacy against S. aureus biofilm increased with HSSP concentration and treatment time. HSSP treatment (10 mg/mL, pH 12.5) of 60 min completely eliminated the biofilm bioactivity (which was approximately 107 CFU/cm2). In contrast, treatment with NaOH solution (pH 12.5) at a pH identical to the HSSP slurry and treatment with sodium hypochlorite (200 µg/mL) caused an approximately four- to five-order reduction in activity. Fluorescence microscopy confirmed that no viable cells remained on the plate after HSSP treatment. Although alkaline and sodium hypochlorite treatments had a stripping effect on the biofilm, many viable cells remained on the plate. HSSP exerted a disinfection effect against S. aureus biofilm that was greater than that provided by alkaline or sodium hypochlorite treatment. This disinfection effect can be effective for controlling bacteria responsible for food poisoning. The use of HSSP in food processing is expected to not only be a source of minerals but also prolong the shelf-life of foodstuffs and reduce the pollution resulting from discarded shells.
The mushroom Agaricus bisporus was stored in packs with different sizes (0, 0.4, 0.8, 1.2 cm2) silicone gum film windows in modified atmosphere system: 100 mL/L O2, 100 mL/L CO2, 800 mL/L N2 at the temperature of 2 ± 1°C for 15 days. The results showed that there were obvious different on O2, CO2 and ethylene concentrations, respiration rate, ascorbic acid content, protein content and sensory characteristics among the mushroom stored in packs with different sizes silicone gum film windows. The packs with a 0.8 cm2 silicone gum film window kept an in-packe gas composition of O2 31 mL/L to 37 mL/L, CO2 under 137 mL/L and ethylene under 14.36 µL/L, and these gas compositions were optimum for maintaining mushroom quality, which kept mushroom with good sensory, low respiration rate, low electrolyte leakage (13.3%) and low loss of ascorbic acid content (only dropped 19.2%) and protein content (only dropped 3.7%).
Lactic acid bacteria (LAB) were isolated from takanazuke produced by using harvested takana in the Aso area. Eight strains were identified from the results of partial 16S rRNA gene sequence analysis: Enterococcus faecium, Leuconostoc mesenteroides, Lactobacillus sakei, L. curvatus, L. (para)plantarum, L. brevis, L. parabrevis, and Pediococcus parvulus. Leu. mesenteroides shared the same sequence with L. delbrueckii subsp. bulgaricus. However, they were differentiated by microscopic observation and a sugar assimilation test. In the fermentation tests using MRS and takana juice medium, L. sakei showed a different ratio of L-lactate to D-lactate from L. curvatus, although they had a similar 16S rRNA gene sequence. This difference was supposed to be based on the inhibitory effect of sodium acetate on lactate racemase. L. (para)plantarum and P. parvulus were selected as starter LABs since they decreased pH and produced high concentrations of lactate in both MRS and tanaka juice media.
The objective of this investigation is to evaluate the possibility of strawberry pigments used in the manufacture of pork sausage. Five treatments of pork sausages (5% fat) with two levels of sodium nitrite (0 and 0.015%), three levels (0.1%, 0.2% and 0.3%) of strawberry pigments were produced. The addition of strawberry pigments resulted in the significant increase of a* values and b* values, but the significant reduction of L* values, VBN values and TBA values (p < 0.05). The 0.1% or 0.2% strawberry pigments added samples had better color and sensory qualities (color, flavor, mouthfeel and slice traits) than the controls, equal even better color and sensory qualities than the NaNO2. Based mainly on the results of overall acceptability during 29 days storage, it could be concluded that strawberry pigments showed a potential for pork sausage manufacture.
A compound natural preservative (CNP) was produced by mixing clove cinnamon extracts with tea polyphenol, chitosan, propolis, nisin and lysozyme. Its effects on microbiological [total aerobic counts (TACs)], chemical [total volatile base nitrogen (TVB-N), 2-thiobarbituric reactive substances (TBARS), total reducing activity (TRA) and pH values], and colorimetric characteristics of chilled beef and mutton that were kept under vacuum packaging during refrigerated storage at 4 ± 1°C were investigated for 4 weeks. Results indicated that the CNP significantly inhibited the growth of microbes, improved TRA values, and decreased TBARS and TVB-N values to some extent especially at the later storage time, but had no obvious advantage in maintaining the color stability of beef and mutton when compared to lactic acid (LA, positive control) and sterile distilled water (DW, negative control). The shelf-lives of chilled beef and mutton were observed to be 3 − 4 weeks for the CNP treatment. The susceptibility of meat species to lipid oxidation was greater in beef than mutton, but spoilage as a consequence of bacteria load was greater in mutton than beef.
Jumbo squid (Dosidicus gigas) is an important fishery resource in Mexico. It is abundant, but with little or nothing added value, therefore is necessary to search alternatives of processing. Due to its muscle characteristics, the aim of this study was to obtain protein concentrates by means of alkaline-aided solubilization followed by isoelectric protein precipitation. A protein concentrate (PC) was obtained from jumbo squid, and then compared with unwashed mantle mince (M). Surface hydrophobicity of PC was lower than M. Zeta potential showed a major potential of aggregation for PC. The total and reactive sulfhydryls groups were higher in M, while in sol-gel transition a reduction of total sulfhydryl groups was noticed. Thermogravimetric analysis revealed that PC loses water more easily that M, while the rheological evaluation showed that M formed a more elastic gel. The gelling properties of PC and M are governed by the physicochemical properties of proteins, which are affected by processing conditions.
With the aim to find out structural features for the tyrosinase inhibitory activity, the inhibitory effects of seven paeonol analogues on the diphenolase of mushroom tyrosinase, the interaction between the inhibitors and the copper ions, and the antioxidant activity by DPPH radical were investigated. These paeonol analogues had suggested remarkable inhibition toward tyrosinase. Among them, paeonol (a) exhibited the strongest inhibition activity (IC50 =0.21 mM) as well as showed potent scavenging activity on the DPPH radical. The inhibition kinetics revealed that paeonol (a) was a mixed-type inhibitor, 2′-hydroxy acetophenone (c), 4′-hydroxy acetophenone (d), and 2,4′-dihydroxy acetophenone (e) were competitive inhibitors, while acetophenone (b), 2′-methoxyacetophenone (f), and 4′-methoxy acetophenone (g) behaved as non-competitive inhibitors. The maximum absorbing wavelengths of compounds (c), (d), and (e) showed different significant blue shifts, which could explain that they exhibited competitive inhibition by forming a chelate with the copper ions at the catalytic domain of the tyrosinase.
Several soybean- and soy product-based allergens have been reported. However, a full analysis of soybean sprout allergens remains to be conducted. Soybean sprout allergy is related to soy intolerance. Here we report a case of anaphylaxis induced by soybean sprouts in a 49-year-old woman. We performed a skin prick test, allergen-specific IgE identification using microarray assay (ImmunoCAP®-ISAC), SDS-PAGE, and immunoblotting for allergen analysis. The ImmunoCAP®-ISAC microarray assay detected Gly m 4 in the soybean sprout. However, immunoblotting revealed two 100-kDa protein bands that did not correspond to Gly m 4 (17 kDa). Therefore, we propose that this patient was not only sensitized to the Gly m 4 allergen, but also to the novel 100-kDa protein.
The amino acid profile of oyster (Ostrea plicatula Gmelin) peptides (OP) was assayed. Its in vitro antioxidant activity was determined, and its in vivo anti-fatigue activity was compared with those of oyster meat and oyster protein. Seven amino acids that may play an important role in enhancing antioxidant activity account for 25.8% of total OP content. These amino acids are histidine, proline, methionine, cysteine, tyrosine, tryptophan, and phenylalanine. The F-value of OP was 4.89, and the concentration of taurine was 45.43 mmol/mL. OP acted as a scavenger for hydroxyl radicals, 1,1-diphenyl-2-picrylhydrazyl, and superoxide anion radicals. It also inhibited lipid peroxidation. The intragastric administration of OP prolonged the swimming time to exhaustion of mice by 78% over that of the control. It decreased the levels of serum lactic acid and blood urea nitrogen by 24.8% and 11.2%, respectively. Finally, it increased the levels of liver glycogen (1.0-fold) and gastrocnemius muscle glycogen (55.6%).
Encapsulation of curcumin-loaded oil droplets with chitosan-based cryogels, made from a ternary system of colloidal chitosan, κ-carrageenan, and carboxymethylcellulose (CMC) sodium salt, was carried out and the effects of the freezing condition (unidirectional freezing rate with and without post-freezing incubation) and the initial concentration ratio of carrageenan to CMC on the properties of the cryogel nanocapsules were experimentally investigated. Both the freezing condition and initial concentration ratio had significant effects on the gel fraction yield, swelling extent, particle size and zeta potential, as well as the curcumin release pattern. Specimen I-S1-02, which was made of polymer set 1 (carrageenan:CMC = 4:6) at a rapid freezing rate of −2°C/min with 10-hr incubation at −10°C, showed the slowest release rate (first-order type) of curcumin. In comparison, it was found that microcapsules obtained by spray-drying a similar O/W curcumin emulsion with dextran as stabilizer exhibited the fastest rate of curcumin release, similar to a burst release.
We studied a method for producing high concentrations of γ-aminobutyric acid (GABA) in pumpkin tissue using freeze-thaw infusion. We introduced L-glutamic acid monosodium salt (MSG) into pumpkins by freeze thaw infusion, and observed that high concentrations of GABA were produced due to the action of the glutamate decarboxylase present in the pumpkins. For an enzyme reaction at 3°C, the amount of GABA peaked when the MSG concentration was 1% (w/w) and enzyme reaction time was about 48 h. When a softening enzyme (Macerozyme 2A) was added together with MSG and infusion was performed, a soft pumpkin that contained GABA at high concentrations was obtained. By freeze-thawing with MSG, it is now possible to manufacture functional foods that have two added values, i.e., in addition to enrichment of GABA, their hardness can also be adjusted.
A new method for the determination of copper in edible oils was suggested. The proposed method is based on the extraction of copper with N,N′-bis(5-methoxy-salicylidene)-2-hydroxy-1,3-propanediamine (5MSHP) followed by flame atomic absorption spectrometry measurement. Firstly, copper complex with 5MSHP was investigated spectrophotometrically. After the analytical properties of the complexation had been defined, optimization of the extraction conditions of copper from oils was performed using a central composite design. Optimal conditions for the extraction of copper with 5MSHP were found to be 26.7°C, 1.3 mL g-1, 5.6 min for the temperature, the ratio of the volume of used Schiff base solution to the amount of oil, and the stirring time, respectively. The proposed method has been validated by using oil based metal standard, obtaining satisfactory results. The limit of detection (LOD) and the relative standard deviation of the method were found to be 0.06 µg g-1 and 2.31% respectively. The method has been successfully applied to the analysis of various oil samples, and the accuracy was assessed by an alternative determination procedure by ICP OES. The concentrations of copper in olive, sunflower, corn and hazelnut oils were found to be 0.41 ± 0.03, 0.31 ± 0.03, 0.29 ± 0.04, 0.28 ± 0.01 µg g-1 in the present work, respectively.
Turmeric (Curcuma longa) rhizome contains abundant curcuminoids, which are highly hydrophobic bioactive compounds. This study aimed to extract curcuminoids using edible oil instead of chemical solvents, and a new extraction system using natural medium-chain triacylglycerols (MCTs) was constructed. After grinding turmeric with MCTs, the liquid and solid fractions were separated by pressing and filtering, with the resulting liquid subsequently clarified by centrifuging and heating. The recovery rate of curcuminoids from turmeric to the clarified MCT fraction was ≈ 10%, but the MCT fraction seemed to be practically saturated with curcuminoids. MCT extracts including curcuminoids can be directly used to add yellow color to many kinds of food, as well as curcuminoid functionality together with the physical and biological properties of MCTs.
Orthogonal experiment was used to optimize the extraction conditions of Flammulina velutipes mycelia polysaccharides (FvP). Four independent variables (ratio of water to raw material, initial pH value, extracting temperature, and extracting time) were taken into consideration. A yield of FvP of 2.19% was obtained under an optimized condition (ratio of water to material of 50:1, initial pH value of 6.0, extracting temperature of 85°C, and extracting time of 6 h). Subsequently, antioxidative properties of FvP-2 (crude polysaccharides) and FvP-3 (deproteinized polysaccharides) prepared from F. velutipes mycelia were evaluated by monitoring the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical and hydroxyl radical scavenging activity, together with antitumor activity against the human hepatocellular carcinoma BEL-7402 cells. DPPH scavenging rate of 65.85% and hydroxyl radical scavenging rate of 71.24% were obtained at 200 μg/mL of FvP-3. The inhibition rate of BEL-7402 cells was up to 45% at 640 μg/mL of FvP-2. These results suggested that FvP possesses potent antioxidant and antitumor properties. The polysaccharide may be useful as a functional food additive and an antioxidant and antitumor agent.
The present study aimed to develop and evaluate a reverse transcription- polymerase chain reaction (RT-PCR) assay that incorporated immunomagnetic beads (IMS/RT-PCR) coated with a monoclonal antibody (Mab) for the separation and detection of noroviruses (NVs, genogroup II) in oysters. Mab-coated beads and polyclonal antibody (Pab)-coated beads were added to oyster extracts containing a series of tenfold dilution of NVs-positive fecal extracts. The oyster extracts were also treated with Proteinase K method. RNA was extracted and used as template for RT-PCR. Mab-based IMS/RT-PCR could detecte 10 RT PCR unit in oyster homogenate, it was 10 times more sensitive than Pab-based IMS/RT-PCR, and 102 times more sensitive than proteinase K/RT-PCR. Analysis of 473 oysters showed that Mab-based IMS/RT-PCR has the highest percentage of positive samples (5.29%), followed by Pab-based IMS/RT-PCR (3.81%), and proteinase K/RT-PCR (2.11%). Mab-based IMS/RT-PCR is a sensitive method for the detection of NVs in oysters and could be a good candidate for routine screening and risk assessment.
Effects of inhomogeneous spatial distribution of aroma compounds were investigated on the perceived aroma intensity and human eating behavior using polysaccharide gels as a food model. Gels tested were structured using gel-in-gel configuration to create different degrees of inhomogeneous spatial aroma distribution, and their pH values were set at neutral (6.7 − 6.8). There were no differences in mechanical properties between the structured gels. A greater degree of inhomogeneous spatial aroma distribution increased the perceived aroma intensity, increased the duration of oral processing and suprahyoid musculature activity during oral processing, decreased the particle size of the bolus, and increased the saliva content in the bolus. Effects of pH were compared with our previous report using the same experimental design but different pH (approximately 4.2), confirming a similar trend in the results. A strategy of food structure design for enhanced perceived aroma intensity and human eating behavior was suggested regardless of gel pH.
Black soybean seed coat is a rich source of polyphenols reported to have various physiological functions. The present study investigated the potential protective effects of polyphenolic extracts from black soybean seed coat on mutagen-induced DNA damage in Salmonella typhimurium. Results from the Ames test using Salmonella stains revealed that black soybean seed coat extract (BE) at 5000 µg/plate showed neither mutagenicity nor cytotoxicity. In contrast, BE, its component cyanidin 3-glucoside (C3G), or procyanidin-rich BE (PC-rich BE) dose-dependently inhibited B(a)P- and 4NQO-induced mutagenesis in the rank order: C3G > BE > PC-rich BE. At 5 μM/plate, C3G and procyanidins, the major polyphenols in BE, inhibited B(a)P-induced mutagenesis in TA 98 and TA 100 by 28 − 59%. They also inhibited 4NQO-induced mutagenesis by 26 − 56%. Collectively, we found that C3G and procyanidins, which are the main active compounds in BE, effectively protected against DNA mutagenic damage in Salmonella typhimurium.
This study was conducted to investigate the effect of drying time on creatine/creatinine ratios, and subsequently taste of herring fillet. Creatine and creatinine contents were quantified during drying of herring fillet by hydrophilic interaction liquid chromatography (HILIC) and their effect on sensory perception was determined. Results showed that creatine content decreased significantly (p < 0.05), while creatinine content increased during the drying period. Creatinine/creatine ratio of herring fillet increased significantly (p < 0.05) up to the eighth day of drying and plateaued out thereafter. Sensory evaluation revealed that addition of a mixture of creatine and creatinine (at the ratio between 95:5 and 75:25) to the Japanese noodle soup resulted in optimum flavor enhancement of soup characteristics such as thickness, mouthfulness and continuity. These results suggest that for dried herring fillet, optimum creatinine/creatine ratios are reached after 10 days of drying.
Water-insoluble gel was prepared from persimmon tannin (PT) solution by the autoxidation process. The gelation reaction proceeded by applying oxygen gas and natural light to the aqueous PT solution, without using harmful reagents or catalysts. Adsorption behavior of the PT gel was assessed using caffeine. Batch adsorption studies were conducted to evaluate the influence of experimental parameters such as contact time, initial concentration of adsorbates, adsorbent dose and temperature. The equilibrium data were analyzed using Freundlich and Langmuir isotherm models. Thermodynamic parameters such as Gibbs free energy, enthalpy, and entropy changes were also calculated, showing that caffeine adsorption on the PT gel is an exothermic process and feasible at lower temperatures. The present results suggest that the PT gel can be used as an effective adsorbent for removing caffeine from solutions.
Ferulic acid (FA) and ethyl ferulate (EF) in sake and mirin samples were quantified. Concentrations of FA and EF in the sake and mirin samples showed high correlations (r = 0.91 and 0.89, respectively). The highest level of EF in the sake samples was ca. 14-fold that of the mirin samples. Thresholds of FA and EF in a sake sample were estimated using a pipette method as 0.075 mg/L and 0.39 mg/L, respectively, by eight assessors in their twenties. The FA threshold was far lower than the highest level of FA in the sake samples, which suggested that FA might affect the sensory quality of sake. FA added to the sake sample showed unpleasant bitter, astringent, “egumi”, or irritating taste characteristics. Sensory and instrumental analyses suggested that EF has the ability to mitigate the taste of FA in sake.
The traditional fermented food ika-kurozukuri, salted squid with ink and liver, is a noted product of Toyama prefecture. Compared with traditional ika-kurozukuri, the salt content of the modern type of product is considerably lower. The microflora of three commercial ika-kurozukuri was investigated using the 16S rDNA clone library method. Staphylococcus saprophyticus was dominant in one product, while Weissella paramesenteroides dominated in the other two products. During ripening at 10°C, the microflora of the modern ika-kurozukuri (6% NaCl content) was analyzed periodically. At the beginning of ripening, Sphingomonas sp. was in the majority. After 10 days of ripening, S. saprophyticus was dominant, and the microflora was stable up to 35 days. The S. saprophyticus strain isolated from ika-kurozukuri could grow at 10°C. These results suggested that the dominant bacterial species of modern ika-kurozukuri products are S. saprophyticus and W. paramesenteroides.