This paper describes a liquid chromatography inductively coupled plasma mass spectrometry (LC-ICP-MS) method for the determination of low-level sulfite in dry vegetables and fruits. Aqueous 0.1% solution of formaldehyde was chosen as extraction solution for releasing the bound sulfite and forming the more stable hydroxymethanesulfonate (HMS). Sulfite was separated using an anion exchange column with isocratic elution by a 50 mmol•L−1 ammonium nitrate in 0.1% formaldehyde solution (pH 7). Sulfite was detected as 32S16O+ by ICP-MS in DRC O2 gas mode. In the optimum conditions, the linearity of the method is 0.05 – 5 mg•L−1 for sulfite, and the detection limit is 0.02 mg•L−1. The results demonstrated that the method achieved acceptable quantitative recoveries of 78.5% to 91.6% with relative standard deviations (RSDs) < 5%. Compared to the AOAC official method, the proposed method presented advantages of rapid and sensitive.
The effect of electricity on the activity of pectin methylesterase (PME) in tomato juice was studied to determine its inactivation mechanism. In this study, the PME in tomato juice was inactivated by applying high electric field alternating current (HEF-AC), raising the temperature to 85° in 0.01 s, and maintaining that temperature for 3.0 s. Such inactivation by HEF-AC was 100 times faster than that by conventional heating at a temperature range of 55°C to 80°C. Whereas the inactivation rate of extracted PME remained low following conventional heating (< 65°C), HEF-AC (> 75°C) increased the inactivation rate of extracted PME to levels similar to that of non-pulp PME. It was assumed that PME attached to the pulp was released by HEF-AC and subsequently denatured at high temperature.
L-Rhamnose isomerase, an aldose-ketose isomerase, is an important enzyme for rare sugar production. In this paper, L-rhamnose isomerase (L-RhI) from Bacillus subtilis 168 (B. subtilis L-RhI) was cloned and expressed in Bacillus subtilis WB600 for the production of D-allose. The obtained crude L-RhI was then purified through a HisTrap HP affinity chromatography column and an anion-exchange chromatography column. The characteristics of purified L-RhI were analyzed subsequently. The enzyme was activated in presence of Mn2+, and it had thermal advantages as its optimum temperature was 70°C, and 85% of its activity was retained after 4 hours' incubation at 60°C. In addition, isothermal titration calorimetry (ITC) was for the first time employed to determine the isomerization of rare sugars, and the kinetic data showed that B. subtilis L-RhI had relatively low Km values on the substrates of L-rhamnose, L-mannose, D-ribose and D-allose. Using D-psicose as the substrate, no by-products but only D-allose was generated catalyzed by B. subtilis L-RhI, and the yield of 37.51% was obtained when the reaction reached its equilibrium at 60°C.
Analyses of honey produced by Africanized Apis mellifera from cassava flowers were carried out to characterize this product. The results showed satisfactory values within the standards of marketing, except for the apparent sucrose for exporting and hydroxymethylfurfural in Brazil. The honey was properly described by the power law model and exhibited a shear thinning behavior. The viscosity decreased with an increase in temperature. The Arrhenius model gave a good description of temperature effect on apparent viscosity of the honey, where the activation energy determined at a shear rate of 10 s−1 was 69.35 kJ/mol. Cassava flower honey not presented quality indexes within the parameters required by current standards, because to the apparent sucrose content is above the level allowed for exportation. These values need to be observed and monitored in a way that farmers can market the honey produced by Africanized A. mellifera amid the cassava culture with physical and chemical quality.
Alternaria sp. causes discoloration and black spot disease in Pyrus pyrifolia (Japanese or Nashi pear). We investigated the antimicrobial properties of an emulsion oil of natural antimicrobial substances, such as allyl isothiocyanate (AITC) and lemongrass oil. The effect of oil-droplet size in the emulsified oil containing AITC and lemongrass oil with modified starch was assessed. Furthermore, the effect of different oil ratios on the antimicrobial properties was also investigated. When the emulsion oil weight ratio of AITC to lemongrass oil was 0.15, Alternaria sp. growth was not observed after 16 days. In paper bags coated with the emulsified oil, the amount of lemongrass oil retained on the paper increased with a decrease in the average oil-droplet size.
The present study compared physicochemical parameters, total phenolic and total flavonoid contents, individual phenolics, and antioxidant activity of litchi juice processed by high pressure carbon dioxide (HPCD), high temperature and ultra high temperature treatments. The results showed that HPCD can retain color of litchi juice better than thermal processing (p < 0.05), while three processing methods had no influence on pH and total soluble solid in litchi juice. Compared to thermal processing, HPCD processed litchi juice had more total phenolics, total flavonoid and individual phenolics including rutin, (−)-epicatechin and chlorogenic acid (p < 0.05). Furthermore, the antioxidant activity of litchi juice was analyzed by 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) assays. The result indicated that HPCD processing can preserve the antioxidant activity better than thermal processing (p < 0.05). This study suggested that HPCD could be used as an alternative of traditional thermal processing to produce more fresh fruit juice.
Powdered white and black peppers were treated with high-pressure oxygen (10 MPa) or carbon dioxide (5 MPa) at 70 – 100°C to decrease the microbial populations. The degree of microbial reduction in the pepper after treatment with high-pressure gases was dependent on the temperature and duration of treatment. Mesophilic aerobic bacterial counts of less than 103 CFU/g in white and black pepper were achieved with gas pressurization at 100°C for 10 and 40 min, respectively. The reduction in the microbial population of the two types of pepper was attributed to the microbicidal effects of high-pressure gas and heat treatment. The piperine content of the pepper treated with gases decreased by approximately 10%. However, treated pepper also showed lower L* values, indicating a darker color, and qualitative alterations in volatile compounds.
Internal and external qualities of mangoes during storage were evaluated by hyperspectral spectroscopy. Green mature mangoes were harvested in Okinawa Prefecture, Japan, and stored for 14 d at 27°C [relative humidity 90%]. Spectral reflectance (380 – 1000 nm), anthocyanin concentration, chlorophyll concentration in skin, and soluble solid content (SSC) in flesh were measured during storage. Anthocyanin concentration and SSC were nondestructively determined with correlation coefficients of 0.88 [root mean square error of cross validation (RMSECV) 2.96 mg·100 g f.w.−1] and 0.73 (RMSECV 0.98%), respectively, using partial least squares regression (PLSR) models. The proposed nondestructive method may be effective for evaluating internal and external qualities of mangoes simultaneously.
The aim of this study was to identify and determine the qualitative and quantitative composition of furanocoumarins in anatomical parts (blade and petiole) of two cultivars of ribbed celery, depending on the age of the plant. Two accurate, precise and inexpensive techniques for analytical detection of coumarin in a relatively short period of time were used in the present study. TLC - the method considered as preliminary, showed the presence of psolaren, bergapten, xanthotoxin and simple coumarin - umbelliferone. Additionally, isopimpinellin was detected by HPLC method. Chromatographic analysis of ribbed celery leaves showed the presence of four furanocoumarins. Psoralen and isopimpinellin are dominant in the leaf blades, wherein content is correlated with the term of harvesting. Bergapten was dominant in petioles regardless of the harvesting time and cultivar.
We manufactured a new fermented tea by tea-rolling processing of third crop green tea (Camellia sinensis) leaves and unripe satsuma mandarin (Citrus unshiu) fruits, and investigated the effects of feeding the tea extract on serum and liver lipid concentrations in rats. The tea extract contained narirutin and hesperidin from unripe satsuma mandarin fruits, catechins from green tea leaves, and black tea polyphenols produced by oxidation of catechins. The fermented tea extract inhibited pancreatic lipase activity in vitro. When rats were fed diets supplemented with the freeze-dried tea extract (0.50% or 0.75%) for 4 weeks, hepatic triglyceride and cholesterol concentrations were reduced in a dose-dependent manner, and the reductions were significant in rats fed diet composed of 0.75% tea extract compared to those fed the control diet. These results suggest that the tea produced by mixing third crop green tea leaves and unripe satsuma mandarin fruits has a hypolipidemic property.
In this study, the effect of glyceraldehyde 3-phosphate dehydrogenase (G3PD) on the molecular state of porcine myofibrils was investigated by observing the structural changes in myosin and actin in myofibrils using phase-contrast and fluorescence microscopy. Though the myofibril gel strength was not influenced by G3PD at a G3PD to myofibril weight ratio (G/M ratio) of 1/20, the gel strength significantly increased at a G/M ratio ≥ 1/10. SDS-PAGE analysis demonstrated that myosin heavy chain band intensity increased in the myofibril soluble fraction by adding G3PD, suggesting G3PD facilitated the solubilization of myosin and actin. Phase-contrast microscopy also showed increased myofibril solubilization with increasing G3PD. Fluorescence microscopy revealed that G3PD colocalized with actin segments. Myosin segments also colocalized with actin segments in G3PD-treated myofibrils, suggesting myosin bound to actin. The addition of G3PD to myofibrils increased the Mg2+- and Mg2+-EGTA-ATPase activities, suggesting G3PD would not change the conformation of myofibrils.
About 8 million tons of jujube pomace arise within a year in China. Bioconversion of food processing residues is receiving increased attention because these residual materials represent a possible and utilizable resource for conversion into useful products. To explore the application of Chinese jujube (Ziziphus jujube Mill.) seeds protein concentrate (ZPI) in food industry, its physiochemical and functional properties were analyzed in this study. The free sulfhydryl content of ZPI is 7.1 × 10−6 mol/g of protein at pH 8.0. Differential scanning calorimetry analyses showed that ZPI had only one endothermic peak with denaturation temperature of about 91°C. Amino acid analyses revealed that ZPI exhibited high levels of glutamic acid, aspartic acid and arginine. The least gelation concentration (LGC) of ZPI is ∼8% at pH 7.0, whereas the protein solubility, emulsifying activity, emulsion stability, and water-holding capacity of ZPI were much lower than those of soybean protein concentrate (SPI). These results suggest that ZPI could be used as a valuable source of protein and gel.
Breast cancer is the mostly commonly diagnosed cancer in women worldwide. Using food-based approach to breast cancer chemoprevention has attracted a great deal of attention in recent years. In the present study, α-lactalbumin was purified from fresh bovine milk and the complex with oleic acid (BLA-OA Complex) was prepared by chromatographic method. The cytotoxic and apoptotic activities of BLA-OA complex on human ER-positive MCF-7 and ER-negative MDA-MB-231 breast cancer cells was investigated by morphological observation, MTS assay, LDH release, DAPI staining, DNA ladder assay and cell cycle analysis. The results showed that BLA-OA complex inhibits cells growth and induces apoptosis in both human ER-positive MCF-7 and ER-negative MDA-MB-231 breast cancer cell lines. The findings of this study are positive for cow milk industry and human breast cancer chemoprevention.
Inhibitory effects of oligomeric polyphenols extracted from peanut skin on α-amylase, maltase, sucrase and glucose transport were investigated. Epicatechin-(4β→6)-epicatechin-(2β→O→7, 4β→8)-catechin (EEC) as a procyanidin trimer inhibited α-amylase activity in a dose-dependent manner, while (+)-catechin and procyanidin A1 as a procyanidin dimer did not show any inhibitory activity up to 5 mg/mL. In the case of sucrase, EEC showed inhibitory activity stronger than (+)-catechin and procyanidin A1. Inhibitory effects of peanut skin on glucose transport in the small intestine were also investigated. The level of glucose transport in Caco-2 cells was significantly decreased by EEC compared to (+)-catechin. These results suggest that the inhibitory effects of procyanidins on α-amylase and α-glucosidase, and the suppression of intestinal glucose transport may change with the degree of polymerization.
The effect of chili pepper leaves (CPL) on the sensory characteristics, microbial load, consumer acceptability, and nutritional quality of salt bread was evaluated. Crushed and powdered CPLs were used in salt bread at different substitution levels: 0 (control), 0.5, 1, 2, 3 and 4% (wt/wt flour). All sensory attributes of salt breads with 0.5% crushed CPL (CCPL) or powdered CPL (PCPL) were comparable with the control. The consumer acceptability for 0.5% CCPL and PCPL were 97 and 93%, respectively. The use of 0.5% CPL in salt bread boosted the β-carotene content from <1 µg/100 g to up to 238 µg/100 g and significantly increased the folate and iron levels. Water activity values were comparable with the control and microbial counts of the enriched products were within acceptable limits. Results showed that CPL can be incorporated in salt bread as a means to improve iron, vitamin A, and folate nutrition in areas where micronutrient malnutrition is prevalent.
Here, we investigated the potential preservation of soymilk by freezing. The physicochemical properties of raw and heated soymilk and the texture of tofu curds prepared using raw and heated soymilk were analysed after freeze-thawing and heating. Centrifugation results revealed increased precipitates in heated soymilk, suggesting that it was not possible to maintain the quality of soymilk before freezing. On the other hand, the physicochemical properties of soymilk and the texture of tofu curds were found to be equivalent when raw soymilk was used, even after freeze-thawing and heating. Furthermore, the viable cell count in raw soymilk did not change after freezing. These results suggested that raw, unheated soymilk may be preserved for long periods by freezing.
Rice noodle is one of the most popular foods consumed in Asia. However, rice flour lacks gluten that forms a cohesive dough structure in wheat-based noodles and for gluten-free, rice-based noodle formulations an alternative to gluten is needed. Therefore, the effects of the addition of hydroxypropyl methylcellulose (HPMC) as a replacement for gluten and the temperature of the water used for rice noodle preparation were investigated. Rice noodle contained high-viscosity HPMC (6%) had the smallest breakdown and the largest setback viscosity, also had better texture and sensory properties. The use of dough water at 80°C was effective on reducing the cooking loss and improving the textural properties. The overall acceptability score was higher compared to that of the control. The results showed that using high-viscosity HPMC (6%) to replace gluten and kneading with water at 80°C was the most effective protocol for improving the quality of gluten-free rice noodles.
Yeast lacking Cu,Zn-superoxide dismutase (sod1Δ) exhibits methionine (Met) auxotrophy, primarily due to the depletion of NADPH required in the sulfur assimilation pathway by oxidative stress. In this study, we measured the ability of natural compounds, including ingredients in foods and dietary supplements, to restore the cell growth of sod1Δ in liquid and solid media without Met. Homocysteine at around 0.1 mM fully suppressed auxotrophy but in excess (> 0.4 mM) had a harmful effect. Methionine sulfoxide at concentrations from 0.05 to 0.8 mM and S-adenosylmethione (0.05 to 6.2 mM) completely relieved the growth defects caused by sod1Δ. Ascorbic acid (1 to 50 mM) restored sod1Δ growth, indicating that the action of this antioxidant could improve Met biosynthesis. However, ascorbic acid derivatives, ascorbic acid 2-glucoside and dehydroascorbic acid, did not show any activity. The suppressive effects of cysteine, N-acetylcysteine, and glutathione peaked at 0.1 mM, 0.5 mM, and 0.05 mM, respectively, but an excess of these agents was less effective. Suppression by dithiothreitol confirms that the thiol group is responsible for the amelioration of Met biosynthesis. No growth was restored for other categories of antioxidants including polyphenols, Trolox, melatonin, astaxanthin, and others.