The effect of structural changes on the activity of peroxidase with different initial state under high-pressure freezing.

The combined impact of initial state, pressure, and freezing on peroxidase denaturation during high-pressure freezing (HPF) processing of enzyme-containing foods remains unclear. This study investigated solid-liquid (initial low/high concentration) biphasic peroxidase using spectroscopic and computer simulation techniques to analyze structural changes affecting peroxidase (POD) activity under HPF. The results indicate that the primary factors determining POD activity during HPF treatment can be ranked as follows: concentration > physical state > pressure > freezing. Higher initial concentrations strengthen protein interactions, leading to a 1% increase in the molecular diameter and a 34% increase in molecular height of HL-POD, thereby increasing aggregation likelihood during crystallization and facilitating structural changes that activate enzymes by 6-17%. The amide I peak proves to be a reliable indicator for monitoring both POD activity and structural alterations. This study offers valuable insights for optimizing HPF technology in food processing.

Comparing the differences in quality profiles and antioxidant activity in seven pumpkin cultivars (Cucurbita moschata and Cucurbita maxima) at harvest and during postharvest storage.

Pumpkin, nutritious vegetable, is renowned for its extended shelf life. In this study, seven pumpkin cultivars from Cucurbita moschata and Cucurbita maxima were comparatively characterized for 25 physiochemical quality factors, starch granule structures, antioxidant activity, and correlations at 0-60 days of postharvest (dop). The findings revealed that sucrose and carotenoid contents increased in C. moschata, while they initially increased and then decreased in C. maxima. Additionally, acidity, primarily driven by malic acid, decreased in C. maxima but increased in C. maxima. The starch content of C. moschata and C. maxima reached its maximum value at 30 dop and 20 dop, respectively. The DPPH radical scavenging activity correlated with the carotenoid content in both pumpkin species. Conclusively, C. moschata demonstrated improved nutritional and quality at 20-30 dop, while C. maxima exhibited higher commercial suitability at 10-20 dop. The findings suggested that pumpkin storage was crucial for quality improvement.

Analysis of Flavonoid Metabolites in Citrus reticulata 'Chachi' at Different Collection Stages Using UPLC-ESI-MS/MS.

Flavonoids are essential substances with antioxidant properties and high medicinal value. Citrus reticulata 'Chachi' peel (CRCP) is rich in flavonoids and has numerous health benefits. The different maturity periods of CRCP can affect the flavonoid contents and pharmacological effects. In this study, we successfully performed UPLC-ESI-MS/MS-based metabolic analysis to compare the metabolites of CRCP at different harvesting periods (Jul, Aug, Sep, Oct, Nov, and Dec) using a systematic approach. The results revealed the identification of a total of 168 flavonoid metabolites, including 61 flavones, 54 flavonols, 14 flavone C-glycosides, 14 dihydroflavones, 9 flavanones, 8 isoflavones, 3 flavanols, 3 dihydroflavonols, and 2 chalcones. Clustering analysis and PCA were used to separate the CRCP samples collected at different stages. Furthermore, from July to December, the relative contents of isoflavones, dihydroflavones, and dihydroflavonols gradually increased and flavanols gradually decreased over time. The relative content of flavonoid C-glycosides showed an increasing and then decreasing trend, reaching the highest value in August. This study contributes to a better understanding of flavonoid metabolites in CRCP at different harvesting stages and informs their potential future utilization.

Enhanced catalytic ozonation performance by CuOx nanoclusters/TiO2 nanotube and an insight into the catalytic mechanism.

Highly reactive nanoclusters of metal oxides are extremely difficult to be synthesized due to their thermodynamic instability. For the first time, CuOx nanoclusters supported on anatase TiO2 nanotubes (NT) with many defects as anchoring sites were successfully prepared. Although the copper loading reached as high as 2.5 %, the size of CuOx nanoclusters in the sample of 2.5 %CuOx/NT were mainly around 1.0 nm. The aggregation of copper species during the calcination process was undoubtedly hampered by the anchoring effects of the abundant defects in NT support. Due to the highly exposed undercoordinated atoms of CuOx nanoclusters, the mixed valences of copper, and the strong interface interaction between CuOx nanoclusters and NT support, 2.5 %CuOx/NT-catalyzed ozonation showed the highest pseudo-first-order reaction rate constant of 8.5 × 10-2 min-1, 2.2 and 4.0 times that of NT-catalyzed ozonation and ozonation alone, respectively. Finally, the catalytic mechanism was revealed by both experiments and density functional theory calculations (DFT). The results demonstrated that the undercoordinated Cu in CuOx/NT could highly promote the adsorption of ozone with a high adsorption energy of -125.16 eV and the adsorbed ozone was activated immediately, tending to dissociate into a O2 molecule and a surface O atom. Thus, abundant reactive oxygen species, e.g., hydroxyl radical (·OH), superoxide radical (·O2-) and singlet oxygen (1O2), could be generated via chain reactions. Especially, ·OH mainly contributed to the removal of ibuprofen pollutants. This work sheds a light on the design and preparation of highly reactive nanoclusters of metal oxide catalysts for catalytic ozonation of refractory organic pollutants.

Effects of selected Bacillus strains on the biogenic amines, bioactive ingredients and antioxidant capacity of shuidouchi.

The control of biogenic amines (BAs) is crucial to guarantee the safety of fermented soybean products. In this study, the BAs composition of eleven shuidouchi samples was analyzed, and the BAs degradation strains were selected from shuidouchi samples with a low BAs content. Then the influences of screened BAs degradation strains on BAs, total phenolics (TP), total flavonoids (TF), isoflavones and the antioxidant ability of fermented shuidouchi were evaluated. Results showed that the total BAs content of all shuidouchi samples was within the safe range, while the GZXQ, GZQY and GZMX samples had higher levels of tyramine. Meanwhile, 109 strains were isolated from the YNLJ, GZLG, GZMZ, GZDY, and YNHY sample. Bacillus tropicus A11, Bacillus siamensis D11, Bacillus subtilis T2, and B. subtilis U2 with higher BAs degradation capacity and lower BAs production ability were selected to ferment shuidouchi. These four Bacillus strains could effectively control the BAs concentration of fermented shuidouchi, especially B. tropicus A11 and B. siamensis D11. Furthermore, compared to naturally fermented shuidouchi, higher levels of antioxidant ability, TP, TF, daidzein, glyciein, and genistein were found in the shuidouchi fermented with selected strains. These findings demonstrated that these screened strains could be applied as potential candidates for the production of high quality shuidouchi.

Cellulose nanofiber from pomelo spongy tissue as a novel particle stabilizer for Pickering emulsion.

For the high-value utilization of agricultural wastes to promote sustainable development, in this work, pomelo spongy tissue cellulose nanofibers (PCNFs) with lengths >3 µm and widths 33-64 nm were prepared by high pressure homogenization (HPH). The PCNFs were used to stabilized Pickering emulsion, and the emulsion with oil phase fraction in the range of 10 % to 50 % (w/w) exhibited outstanding stability. The increase in PCNFs concentration also enhanced the three-dimensional network structure, resulting in higher stability of the emulsion. Moreover, the droplet size distribution of emulsion would be greatly improved by moderate heating. No creaming was observed in emulsions over a wide range of ionic strengths (20-200 mM) after storage for 30 d. And the excellent emulsifying properties of the PCNFs were mainly attributed to their adsorption at the oil-water interface and the formation of a three-dimensional network structure. All the results indicated that the PCNF would be a promising novel stabilizer for Pickering emulsions.

Classification of Pericarpium Citri Reticulatae (Chenpi) age using surface-enhanced Raman spectroscopy.

Pericarpium Citri Reticulatae (PCR) is used in food and medical herbal formula, and its quality is determined by its age. Raman spectroscopy is a laser technology for molecular fingerprinting. The feasibility of using surface-enhanced Raman spectroscopy (SERS) to determine the PCR age was investigated. The Raman peaks were acquired using a Raman spectrometer with a 785 nm diode laser and were analyzed using principal component analysis (PCA) followed by linear discriminant analysis (PCA-LDA). There were six major peaks at 600, 730, 990, 1370, 1607, and 1742 cm-1 in the SERS spectra, and their intensity, especially the peak at 1607 cm-1, was inversely correlated with the PCR age. The different ages of PCR could be correctly classified with over 90 % accuracy by using PCA-LDA based on the SERS spectra. In conclusion, a Raman spectrometer may be used as a novel method to identify the age of PCR products.

Citri Reticulatae Pericarpium (Chenpi) Protects against Endothelial Dysfunction and Vascular Inflammation in Diabetic Rats.

Dried tangerine peel (Citri reticulatae Pericarpium, CRP; Chenpi in Chinese) possesses medicine and food homology with hypolipidemic, anti-inflammatory and antioxidant activities. This study aimed to explore the protective effect of CRP extract on endothelial function and inflammation in type 2 diabetic rats and the related mechanisms. Type 2 diabetes mellitus was induced by high-fat diet (HFD)/streptozotocin (STZ) in male Sprague Dawley rats, and CRP extract was orally administered at 400 mg/kg/day for 4 weeks. Rat and mouse aortas were treated with high glucose and CRP extract ex vivo. The data showed that the ethanolic extract of CRP normalized blood pressure and the plasma lipid profile as well as the plasma levels of liver enzymes in diabetic rats. Impaired endothelium-dependent relaxations in aortas, carotid arteries and renal arteries were improved. CRP extract suppressed vascular inflammatory markers and induced AMPK activation in aortas of diabetic rats. Exposure to high glucose impaired vasodilation in aortas of rats and mice, and this impairment was prevented by co-incubation with CRP extract. In conclusion, our findings suggest that CRP extract protects endothelial function by inhibiting the vascular inflammatory state on activation of AMPK in diabetic rats.

Physicochemical, structural and functional properties of pomelo spongy tissue pectin modified by different green physical methods: A comparison.

Pectin is a valuable bioactive ingredient, but its practical application is limited in many areas due to its high molecular weight and complex structure. In this work, the effect of different physical methods (ultra-high pressure, ultrasonic, and high-temperature cooking) on the physicochemical, structural, and functional characteristics of pomelo spongy tissue pectin (PP) were investigated. Ultra-high pressure treatment (300 MPa, 15 min) decreased the degree of esterification (DE, 4.53 %) and the degree of acetylation (DA, 2.76 %) of PP. And the PP subjected to the ultrasonic treatment (200 W, 20 min) exhibited the highest esterification degree (66.02 %), galacturonic acid content (GalA, 406.40 mg/g), and degradation enthalpy (66.93 J/g). Meanwhile, the PP treated with high-temperature cooking (HCT, 120 °C, 30 min) had the lowest acetylation degree (2.02 %), molecular weight (8.48 × 104 Da), and GalA content (254.92 mg/g). SEM and XRD results showed that the degradation effect of high temperatures on PP was more evident than other physical modification methods. Remarkably, all modified pectin solutions showed lower viscosity compared to untreated PP solution. Among these PP samples, higher antioxidant activity (103.29-134.22 mmol TE/g FRAP and 646.27-705.25 mmol TE/g ORAC values) was found in the HCT-treated PP. Moreover, the ultra-high pressure and ultrasound modified pectins revealed better emulsifying activity and emulsifying stability than unmodified PP. The results of this study indicated that the PP could be treated to achieve the desired functional application through these three physical modification methods.

Yellow pigment from gardenia fruit: structural identification and evaluation of cytotoxic activity in HepG2 cells by induction of apoptosis.

The preparation process of yellow pigment (YP) from gardenia (Gardenia jasminoides) fruit was investigated, and the main components of YP were characterized by liquid chromatography-time of flight-mass spectrometer/mass spectrometer (LC-TOF-MS/MS). Furthermore, cytotoxic activity in HepG2 cells by induction of apoptosis was also evaluated. The preparation results indicated that the color value of YP was 498.34, which was 8.6 times higher than crude YP. Fifteen compounds in YP were identified, and crocins were the predominant compounds. The cell experiment results showed that YP inhibited the proliferation of HepG2 cells in a time- and dose-dependent manner. Moreover, YP also inhibited HepG2 cells in G2/M stage, increased the level of intracellular reactive oxygen species (ROS), and enhanced cell apoptosis. Real-time quantitative polymerase chain reaction (RT-PCR) analysis revealed the up-regulation of caspase-3, 8, 9, and bax and down-regulation of bcl-2 in HepG2 cells. Overall, these findings suggested that YP had potential cytotoxic activity in HepG2 cells by induction of apoptosis, which might be beneficial to human health. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-022-01133-9.

Changes of volatile substance composition during processing of nine-processed tangerine peel (Jiuzhi Chenpi) determined by gas chromatography-ion mobility spectrometry.

Nine-processed tangerine peel (Jiuzhi Chenpi in Chinese) is a famous Chinese traditional snack. The composition and contents of volatile substances during its processing is unclear. Gas chromatography combined with ion mobility spectrometry (GC-IMS) was applied to determine the characteristic changes of volatile components throughout the production process. Four stages such as untreated dry tangerine peel (raw material), debittered tangerine peel, pickled tangerine peel, and final product were examined. A total of 110 flavor compounds including terpenes, alcohols, aldehydes, ketones, esters, acids, and two others were successfully detected in tangerine peel samples across the various production stages. There were abundant amounts of terpenes contributing to the flavor, including limonene, gamma-terpinene, alpha-pinene, myrcene, beta-pinene, and alpha-thujene which were reduced at the later stage of production. Large amounts of esters and alcohols such as methyl acetate, furfuryl acetate, ethyl acetate, benzyl propionate, 2-hexanol, linalool, and isopulegol, were diminished at the early stage of processing, i.e., soaking for debittering. One the other hand, the final product contained increased amount of aldehydes and ketones including pentanal, hexanal, 2-hexenal, 2-heptenal (E), 2-pentenal (E), 1-penten-3-one, 6-methyl-5-hepten-2-one, 2-methyl-2-propenal, and 2-cyclohexen-1-one, and very high level of acetic acid. Present findings help to understand the formation of the unique flavor of nine-processed tangerine peel and provide a scientific basis for the optimization of processing methods and quality control.

Upregulation of Thioredoxin Reductase 1 Expression by Flavan-3-Ols Protects Human Kidney Proximal Tubular Cells from Hypoxia-Induced Cell Death.

Renal hypoxia and its associated oxidative stress is a common pathway for the development of kidney diseases, and using dietary antioxidants such as flavan-3-ols to prevent kidney failure has received much attention. This study investigates the molecular mechanism by which flavan-3-ols prevent hypoxia-induced cell death in renal tubular epithelial cells. Human kidney proximal tubular cells (HKC-8) were exposed to hypoxia (1% O2) in the presence of flavan-3-ols (catechin, epicatechin, procyanidin B1, and procyanidin B2). Cell death was examined using flow cytometric analysis. Gene expression was determined using a PCR array and Western blotting, and its network and functions were investigated using STRING databases. Here, we show that the cytoprotective activity of catechin was the highest among these flavan-3-ols against hypoxia-induced cell death in cultured HKC-8 cells. Exposure of HKC-8 cells to hypoxia induced oxidative stress leading to up-regulation of DUOX2, NOX4, CYBB and PTGS2 and down-regulation of TXNRD1 and HSP90AA1. Treatment with catechin or other flavan-3-ols prevented the down-regulation of TXNRD1 expression in hypoxic HKC-8 cells. Overexpression of TXNRD1 prevented hypoxia-induced cell death, and inactivation of TXNRD1 with TRi-1, a specific TXNRD1 inhibitor, reduced the catechin cytoprotection against hypoxia-induced HKC-8 cell death. In conclusion, flavan-3-ols prevent hypoxia-induced cell death in human proximal tubular epithelial cells, which might be mediated by their maintenance of TXNRD1 expression, suggesting that enhancing TXNRD1 expression or activity may become a novel therapeutic strategy to prevent hypoxia-induced kidney damage.

Evaluation of the Structural, Physicochemical and Functional Properties of Dietary Fiber Extracted from Newhall Navel Orange By-Products.

Ultrasound-assisted enzymatic treatment was used to treat Newhall navel orange peel and residue, and then the structural, physicochemical and functional properties of extracted soluble dietary fibers (SDF) and insoluble dietary fibers (IDF) were investigated. The structural properties were determined using scanning electron microscopy, X-ray diffraction, FT-IR and monosaccharide composition. Among these dietary fibers, residue-SDF showed a more complex structure, while peel-IDF exhibited a looser structure. Four samples showed representative infrared spectral features of polysaccharides, typical cellulose crystalline structure and diverse monosaccharide composition. Furthermore, residue-IDF exhibited higher oil-holding capacity (2.08 g/g), water-holding capacity (13.43 g/g) and nitrite ion adsorption capacity (NIAC) than other three samples, and residue-SDF showed the highest swelling capacity (23.33 mL/g), cation exchange capacity (0.89 mmol/g) and cholesterol adsorption capacity (CAC) among these dietary fibers. In summary, this study suggests that the residue-SDF and residue-IDF could be used as the ideal dietary fibers for application in the functional food industry.

Identification of the cooked off-flavor in heat-sterilized lychee (Litchi chinensis Sonn.) juice by means of molecular sensory science.

The main contributors to the cooked off-flavor in heat-sterilized lychee juice (HLJ) were studied by means of molecular sensory science. The HLJ which elicited cooked cabbage/potato and onion/garlic off-flavor was compared with fresh lychee juice (FLJ) having desired sensory attributes via chemical analysis and sensory evaluation. Aroma extract dilution analysis, quantitative analysis and calculation of odor activity values (OAVs) were conducted on both FLJ and HLJ. The results showed that compared with FLJ, 15 compounds had increased OAVs in HLJ, among which, dimethyl sulfide (DMS), methional, dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS) and 2,4-dithiapentane presented cooked cabbage/potato, garlic/onion and sulfurous impression. The omission experiment proved that DMS, methional, DMTS, DMDS, 3-methylbutanal and 2,4-dithiapentane had significantly negative effects on the overall aroma of HLJ. Further studies on HLJs from other varieties of lychee confirmed that DMS, methional, DMTS, DMDS and 3-methylbutanal were responsible for the cooked off-flavor of HLJ in general.

Comparison of pulsed vacuum and ultrasound osmotic dehydration on drying of Chinese ginger (Zingiber officinale Roscoe): Drying characteristics, antioxidant capacity, and volatile profiles.

The effects of pulsed vacuum osmotic dehydration (PVOD) and ultrasound osmotic dehydration (USOD) on drying characteristics and quality attributes of ginger were investigated. PVOD was subjected to pulsed vacuum at 13 kPa for 30 min, and USOD was subjected to ultrasound with the frequency of 40 kHz for 30 min. After PVOD and USOD treatments, the samples were then dried at intermittent microwave & air-drying oven with an output of 700 W and temperature of 60°C to the final moisture content of 0.12 g water/g d.w. The results showed PVOD and USOD treatments could improve the total phenolic contents by -1.8% to 16.4%, total flavonoid content by 7.7%-18.7%, DPPH radical scavenging by 9.5%-12.2%, and ABTS+ antioxidant activity by 17.8%-27.4%, although they prolonged the later stages drying of ginger. Besides, the PVOD- and USOD-pretreated dried samples had less brownings than the untreated-dried samples which could be attributed to the inactivation of polyphenol oxidase (PPO) and peroxidase (POD). The PPO activity was significantly reduced in the PVOD and USOD ginger, whereas POD activity was decreased in USOD ginger but increased in PVOD ginger. Moreover, PVOD pretreatment also led to a better preservation of volatile profiles and cell structure than USOD treatment. Therefore, both PVOD and USOD are effective pretreatments for drying of ginger.

Effect of ethyl oleate pretreatment on blueberry (Vaccinium corymbosum L.): drying kinetics, antioxidant activity, and structure of wax layer.

Blueberry belongs to the genus vaccinium, which is rich in a variety of biologically active components beneficial to the human body. Drying of blueberry is a slow and energy-intensive process because of its waxy skin, which has low permeability to moisture. Therefore, chemical pretreatment of ethyl oleate (AEEO) was adopted to accelerate moisture diffusivity. The results showed that the drying rate of blueberries was increased significantly by AEEO treatment, and the drying time can be shortened by 17.17-40.70%. After AEEO dipping, the effective diffusion coefficient increased from 5.461 × 10-9 to 1.067 × 10-8 m2/s at 60 °C. Six semi-theoretical thin-layer models were used to estimate the curves of air-drying of blueberry, and Wang-Singh model was found to perform better than other models. Besides, the rehydration and retention of nutritional contents were also improved by AEEO dipping. The total phenolics, total flavonoids, total anthocyanin content, and ABTS*+ scavenging activity of blueberry were increased by 37.74%, 21.01%, 47.83%, and 30.75%, respectively. The result of SEM observation and cell-membrane permeability indicated that AEEO could break down the wax layer of blueberry, change the crystal structure of wax layer, and increase cell permeability, which resulted in shorter drying time and higher quality of blueberry.

Anti-asthmatic activity of alkaloid compounds from Pericarpium Citri Reticulatae (Citrus reticulata 'Chachi').

Pericarpium Citri Reticulatae (PCR, Citrus reticulata 'Chachi', Guangchenpi in Chinese) is one of the most famous Chinese citrus herbal medicines. The in vivo anti-asthmatic activity of 'Chachi' PCR was investigated using a histamine-induced experimental asthma model in Guinea pigs. Two alkaloid-type compounds, synephrine and stachydrine, were analyzed and identified in the 'Chachi' PCR alkaloid fraction. The alkaloid fraction and synephrine protected Guinea pigs against histamine-induced experimental asthma in a dose-dependent manner. The respective application of high, middle, and low doses of the 'Chachi' PCR alkaloid fraction significantly increased specific airway resistance by 284%, 328%, and 355%, and decreased dynamic compliance by 57%, 67%, and 75%. A similar change was observed for synephrine. The expression of eosinophils in bronchoalveolar lavage fluid (BALF) and serum IgE, IL-4, and IL-5 levels in histamine-induced experimental asthmatic Guinea pigs were significantly downregulated by the 'Chachi' PCR alkaloid fraction and synephrine compared to the control group, whereas stachydrine did not impart a statistically significant effect on the expression of tested inflammatory cells (leucocytes, eosinophils, neutrophils, and lymphocytes), immunoglobulin (IgE), or cytokines (IL-4 and IL-5). Pathological changes in lung tissues in each treatment group included the infiltration of inflammatory cells around the bronchia.

Persimmon vinegar polyphenols protect against hydrogen peroxide-induced cellular oxidative stress via Nrf2 signalling pathway.

Since polyphenols are known to exhibit antioxidative properties, we prepared and characterized persimmon vinegar polyphenols (PVP) in this study. Furthermore, we investigated the protective effect of PVP on hydrogen peroxide (H2O2)-induced oxidative stress in HepG2 cells and its underlying mechanisms. Our results showed that flavon-3-ols were the predominant polyphenols in PVP. Pre-treatment with PVP significantly decreased (p < 0.05) H2O2-induced cell damage in a dose-dependent manner, accompanied by decrease in lactate dehydrogenase (LDH) leakage, aminotransferase activities, and ROS accumulation. Moreover, PVP upregulated the expression of antioxidative enzymes, such as heme oxygenase-1 (HO-1) and NAD(P)H: quinone oxidoreductase 1 (NQO1), and increased the levels of glutathione. Western blotting results showed that PVP induced the nuclear translocation of nuclear factor (erythroid-derived-2)-related factor 2 (Nrf2). Taken together, our results indicated that PVP effectively protected HepG2 cells against oxidative stress via activation of the Nrf2 antioxidative pathway.

Evaluation of bioactive flavonoids and antioxidant activity in Pericarpium Citri Reticulatae (Citrus reticulata 'Chachi') during storage.

A simple and accurate method using high performance liquid chromatography (HPLC) with dual wavelength detection was developed to simultaneously determine the contents of one flavanone glycoside (hesperidin) and five polymethoxylated flavones (PMFs: sinensetin, 4',5,7,8-tetramethoxyflavone, nobiletin, tangeretin and 5-O-desmethyl nobiletin) in Pericarpium Citri Reticulatae (Citrus reticulata 'Chachi') ('Chachi' PCR). By modifying the mobile phase compositions and detection wavelengths, an optimal HPLC condition was obtained, under which the calibration curves of all six compounds exhibited good linearity (R2>0.99). For all the tested compounds, the relative standard deviation (RSD) was less than 4%, and the accuracy ranged from 97.58 to 103.2%. The developed method was successfully applied to monitor the changes in the contents of six flavonoids in 'Chachi' PCR during storage at 25°C, over a three year period. Color parameters and antioxidant capacity were also determined to evaluate the sample quality. The contents of hesperidin decreased while all the polymethoxylated flavones and antioxidant activities increased throughout the storage period, demonstrating that polymethoxylated flavones could be used as indices for the quality change of Chachi' PCR during storage. The results from this study suggest that the longer storage periods increased the quality of PCR.

Slight Fermentation with Lactobacillus fermentium Improves the Taste (Sugar:Acid Ratio) of Citrus (Citrus reticulata cv. chachiensis) Juice.

The aim of this study was to evaluate the hypothesis that fermentation with Lactobacillus fermentium, which can metabolize citric acid, could be applied in improving the taste (sugar:acid ratio) of citrus juice. During fermentation, the strain of L. fermentium can preferentially utilize citric acid of citrus (Citrus reticulata cv. Chachiensis) juice to support the growth without the consumption of sugar. After 6 h of fermentation with L. fermentium at 30 °C, the sugar:acid ratio of citrus juice increased to 22:1 from 12:1, which resulted in that the hedonic scores of sweetness, acidity and overall acceptability of fermented-pasteurized citrus juice were higher than the unfermented-pasteurized citrus juice. Compared with unfermented-pasteurized citrus juice, the ORAC value and total amino acid showed a reduction, and no significant change (P > 0.05) in the L*, a*, b*, total soluble phenolics and ascorbic acid (Vc) content in the fermented-pasteurized citrus juice was observed as compared with unfermented-pasteurized citrus juice. Hence, slight fermentation with L. fermentium can be used for improving the taste (sugar:acid ratio) of citrus juice with the well retaining of quality.