A new type of portable sensor is proposed to detect bacterial concentration based on the change in dielectric loss angle δ. The performance of the sensor is tested in four types of drinks, namely, milk, orange juice, peach juice, and tomato juice. Notably, the sensor can detect δ when the bacterial concentration reaches a critical threshold value (approximately 106 cfu mL−1) by applying a 1 V peak-to-peak 200 Hz sinusoidal test signal of 0.25 mA at intervals of 10 min. This work introduces a portable and low-system for rapid detection. The system is a useful tool for microbial screening in industrial and commercial environments.

The effects of various factors, including the extraction time, temperature, solvent/material ratio, the ultrasonic intensity and duty cycle of ultrasonic irradiation on the extraction yield of all-trans-lycopene from red grapefruit by ultrasound-assisted extraction (UAE) were investigated. In comparison with conventional solvent extraction (CSE), UAE showed a pronounced greater extraction yield and reduced extraction time effectively with a peak value at 30 min. The extraction yield was significantly influenced by temperature and the optimum condition was 30 °C. The extraction yield increased with increasing of solvent/material ratio until equilibrium was arrived at the optimal ratio of 3:1 (mL/g). The extraction yield increased first and then decreased with an increase in ultrasonic intensity. The extraction yield of UAE increased with the increase of duty cycle, whereas pulsed ultrasound with proper intervals was more efficient than continuous ultrasonication. The degradation via isomerisation of all-trans-lycopene under ultrasonic treatment was also observed with the formation of 9,13′-di-cis-, 9,13-di-cis-, 15-cis-, 13-cis- and 9-cis-lycopene isomers which were tentatively identified by HPLC-PAD.Highlights► Effects of various factors in UAE on all-trans-lycopene yield were investigated. ► The yield was significantly influenced by time, temperature and duty cycle. ► UAE shows considerable advantages on the extraction yield of all-trans-lycopene. ► We explore the stability of all-trans-lycopene with structure changes in UAE. ► A new method to make isomers of lycopene was discovered.

Four types of Chongcai paste (pectin/xanthan/Chongcai, pectin/CMC-Na/Chongcai, CMC-Na/xanthan/Chongcai and pectin/CMC-Na/xanthan/Chongcai) were prepared, and the changes of flavour and colour of pastes were studied during fifteen days of storage. Nine pungent volatiles were detected in Chongcai paste; among the nine volatiles, allyl isothiocyanate (AITC) was the major component, and two volatiles (1-isothiocyanatobutane and n-pentylisothiocyanate) were detected in Cruciferae family plants for the first time. Pectin/xanthan complex applied in the paste proved to have the best capability in holding flavour, and CMC-Na/xanthan was the worst. A pseudo-second order kinetics model was applied to describe the colour change of pastes during storage for the first time, and the results suggested that the colour degradation could be well interpreted by the pseudo-second order kinetic model.Highlights► Flavour and colour of a new kind of paste, Chongcai paste, was investigated during storage. ► Among detected 9 pungent volatiles, 2 new isothiocyanates were found in Cruciferae for the first time. ► Pectin/xanthan complex was proved to have the greatest capability in holding flavour, and CMC/xanthan complex the worst. ► A pseudo-second order kinetics model was used to describe the paste colour change during storage.

The present study was aimed at identification of antifungal components against Penicillium italicum from Chinese propolis with bioassay-guided fractionation technique. Propolis ethanolic extract (PEE) was separated and purified by liquid–liquid extraction and thin layer chromatography (TLC) and the most active band was subjected to HPLC–MS/MS to identify the antifungal compounds. The results showed PEE and its fractions had strong antifungal activity against P. italicum. Among the fractions of PEE partitioned by petroleum ether, ethyl acetate, n-butanol and water, ethyl acetate fraction (E-Fr) exhibited the most effective activity against P. italicum. Further bioautographic TLC assay showed Band I, with Rf value of 0.70, had an inhibitive zone, which showed the strongest antifungal activity and completely inhibited the growth of P.italicum at 200 mg/L. Bioactive components found in Band I were further identified as pinobanksin, pinocembrine, chrysin and galangin. This study exhibited Chinese propolis and its main flavonoids was potential natural alternatives for the control of citrus blue mould caused by P.italicum.Research highlights► Chinese propolis ethanolic extract and its fractions exhibited antifungal activity against Penicillium italicum. ► The bioactive components were identified with bioautographic TLC assay and HPLC–MS. ► The structure-activity relation of the active components was discussed.

A fundamental study of free radical-scavenging activity of three carotenoids purified from water spinach (Ipomoea aquatica cv. Slim leaf) by thin layer chromatography and identified by high performance liquid chromatography–mass spectroscopy (HPLC–MS), namely violaxanthin, lutein and β-carotene, was carried out by measuring the ability to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and 2,2-azobis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radicals and by measuring their ability to inhibit red blood cell homelysis and lipid peroxidation. From the results obtained, it can be seen that the three carotenoids, in the range of 0–8 μg/mL, possessed significant antioxidant activity which increased in a concentration-dependent manner. Among them, violaxanthin, a 5,6-epoxycarotenoid, presented the excellent scavenging capacity, and the IC50 values were 8.77, 3.38, 5.06 and 4.25 μg/mL for each assay, respectively. β-Carotene showed highest scavenging percentage in DPPH free radical assay, whereas violaxanthin was most efficient in the other three assays, the results observed suggested that the relationship between structure and antioxidant activities in vitro was complex, epoxidation of the 5,6-ring may improve the antioxidative activities of the carotenoid in the four detected assays in vitro except the quenching of DPPH radicals.

The potential use of Brettanomyces anomalus PSY-001 as an additional starter culture for the production of Rice-steamed sponge cake (RSSC), a traditional fermented food in China, was investigated. Two productions of RSSC, each containing batches of experimental cakes with Brettanomyces added and reference cakes with the leavened liquid added were carried out. For both experimental and reference cakes, chemical analysis and sensory evaluation were carried out during the fermentation period. The results showed that experimental cakes had desirable aroma and taste. The observed differences indicate a positive contribution to the overall quality of RSSC by B. anomalus PSY-001.

A novel functionalized polymeric flocculant on the basis of Konjac-graft-poly (acrylamide)-co-sodium xanthate was synthesized via copolymerization reaction of crosslinked Konjac glucomannan, acrylamide (AM), and sodium xanthate using epichlorohydrin (ECH) as cross-linker and ceric ammonium nitrate (CAN) as initiator in aqueous solution. The optimal synthesis conditions were as follows: KGM = 3 g, [ECH] = 4.9 × 10−3 mol/L at 35 °C for 2 h, then [CAN] = 4.0 × 10−3 mol/L, and the weight ratio of KGM and AM was 1:3 at 45 °C for 2.5 h, and then [NaOH] = 0.1 mol/L, [CS2] = 59 × 10−3 mol/L at 30 °C for 2 h. The copolymer was characterized by FTIR, DSC and Elemental analysis. Flocculation test shows that in some extent, the cations, pH value, and turbidity are favorable for the removal of Cu2+ ions, but an excess dosage lead to an unobvious effect, and some anions express a negative effect on the Cu2+ removal. There exists the cooperation between Cu2+ ions and turbidity in the removal performance.

β-Cryptoxanthin, a pro-vitamin A carotenoid of potential interest for health, was found in vegetables and fruits in both free and esterified forms. Stabilities of free β-cryptoxanthin (FCX) and its esters including β-cryptoxanthin laurate (CXL), β-cryptoxanthin myristate (CXM), and β-cryptoxanthin palmitate (CXP) against heat were studied by high performance liquid chromatography–mass spectrometry (HPLC–MS). All β-cryptoxanthin fatty acid esters were more stable against heat than FCX. The antioxidant activities of FCX and its esters on superoxide anion, hydroxide radical and singlet oxygen were investigated by the pyrogallol-luminol system, the CuSO4–phenanthroline–Vc–H2O2 system, and OH–NaClO–H2O2 system, respectively, using chemiluminescence (CL) methods in vitro. The antioxidant activities of β-cryptoxanthin fatty acid esters were not significantly different in all methods, furthermore, no synergetic effects amongst them were obtained. These results suggest that esterification of OH groups with fatty acids might not affect antioxidant activity of β-cryptoxanthin but stabilize β-cryptoxanthin against heat degradation.

The differences in lipid content will lead to differences in protein structure and gel properties and it is a nice model system, so our study, based on the production process for Zhongxiang tofu, used soy protein isolate (SPI) as raw material and adopted circular dichroism and Raman spectrum to investigate the influence of different lipid content on protein secondary structure in tofu. Texture profile analysis and differential scanning calorimetry were used to analyze the influence of lipid on gel texture properties and state of water. The interactive mechanism at microscopic level was investigated by means of scanning electron microscopy. The results show that the additional lipid reacted with the soy protein and the lipid became a component of a newly formed molecular membrane. With an increase in added lipid, SPI gel hardness was reduced, while springiness increased. The proportion of α-helix and β-sheet in SPI gel at 16% (w/v) lipid are 4.0 and 26.0%, respectively. The equilibrium water content tended to decrease when lipid content was increased.

Antioxidant capacity of polymethoxylated flavones (PMFs) extracts of Jinchen orange peels (Citrus sinensis Osberk) was evaluated by using a chemiluminescence (CL) method in vitro. PMFs were isolated using a procedure that produced a consistent mixture of PMFs both in identity and in proportion. The mixture mainly consisted of nobiletin (55.9%), sinensetin (15.2%), heptamethoxyflavone (13.2%), and tangeretin (8.1%). The antioxidative effects of PMFs and the main individual flavones in PMFs as well as synergistic effects of PMFs with organic acids (citric acid, oxalic acid, and malic acid) and amino acids (alanine, lysine, serine, and threonine) on superoxide anion were determined by the pyrogallol–luminol system. The results showed that the inhibition by PMFs on superoxide radical was stronger than that of the individual flavones. Mixtures of citric acid and lysine with PMFs had higher synergistic effects than any other tested mixtures, and the optimum concentrations were exhibited by combinations of 7 μg/mL PMFs + 120 μg/mL citric acid (1.2, p < 0.05) and 7 μg/mL PMFs + 42 μg/mL lysine (1.1, p < 0.05). For the other amino acids and organic acids, the values of the measured inhibition effect (% MIE) of the mixtures with PMFs were not significantly different from their expected inhibition effect (% EIE), which did not show synergism.

Free and glycosidically bound volatile compounds in juice and peel of Jincheng oranges were investigated. Solid phase microextraction (SPME) was used for extraction of free volatile compounds. Bound volatile compounds in juice were isolated by using Amberlite XAD-2 column adsorption and methanol elution. Subsequently, they were hydrolyzed by almond β-glucosidase. Acid hydrolysis was also applied on the release of the bound fraction in juice. Both free and bound volatile compounds were then determined by GC-MS. A total of 26 and 40 free volatile compounds were identified in juice and peel, respectively. Terpenes followed by aldehydes were the major free volatile compounds both in juice and peel. Eleven and ten aglycons hydrolyzed by enzyme were identified in juice and peel, respectively. Benzenic compounds and hydroxyl esters were the main bound volatile compounds in juice, while C13-norisoprenoid and monoterpenes were the most abundant bound volatile compounds in peel. 3-Oxo-α-ionol (41%) predominated in bound fraction of peel. Five aglycons hydrolyzed by acid were found in juice. p-Vinylguaiacol and eugenol were the two compounds found both after enzymatic and acid hydrolysis. Rhamnose, xylose, and glucose were determined as sugar moieties in juice.

The effect of spontaneous fermentation and inoculated fermentation on the volatile compounds of orange wine was studied. The differences on volatile compounds of orange juice and orange wine were also observed. The volatile compounds were analyzed by sensory and instrumental analysis. Solid phase microextraction was used for extraction of volatile compounds. Sensory analysis indicated that no significant differences existed on the wine odor between the two methods. A total of 17 and 19 volatile compounds were identified and quantified in spontaneous and inoculated fermentations, respectively. Esters followed by alcohols and terpenes were the most abundant volatile compounds in the two orange wines. Thirteen of these compounds were present both in the two methods. Totally 31 volatile compounds were found in orange juice, and terpenes were quantitatively the dominant group. Esters were found to be the important volatile compounds formed during fermentation, such as isoamyl acetate, ethyl hexanoate, ethyl benzoate, diethyl succinate, ethyl decanoate and ethyl laurate, etc.

•5,7-Dihydroxyflavonoids have antifungal activities against P. italicum.•C-4′-OH and C-3-OH are crucial for antifungal activities of 5,7-dihydroxyflavonoids.•Glycosylation could affect the antifungal activity of 5,7-dihydroxyflavonoids.•The relationship between antifungal activity and respiration inhibition have been discussed.To evaluate the structure-activity relationship of 5,7-dihydroxyflavonoids against P. italicum, we tested the antifungal activity of 23 selected 5,7-dihydroxyflavonoids against spore germination of P. italicum, and the effects of hydroxyl group, hydrogenation, methylation and glycosylation on the antifungal activity are explored. C-4′-OH and C-3-OH are active groups for the 5,7-dihydroxyflavonoids against P. italicum. We find that hydrogenation of the C2/C3 bond decreases the antifungal activity of 5,7-dihydroxyflavonoids. Antifungal activity of 5,7-dihydroxyflavonoids against P. italicum was affected by the conjugation site of glycosylation and the class of sugar moiety. The correlation between antifungal activity and the inhibition of respiration of 5,7-dihydroxyflavonoids was further evaluated. We find no significant relationship among the IC50 of 5,7-dihydroxyflavonoids on spore germination and on respiration. Some 5,7-dihydroxyflavonoids even enhance the respiration of P. italicum. This indicate respiration is not the only target for 5,7-dihydroxyflavonoids against P. italicum.