Antioxidant properties of a vegetable–fruit beverage fermented with two <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> strains

Fermented vegetable–fruit beverages are a popular fermented food, with many potential health benefits. In this study, two commercial Lactobacillus plantarum strains were selected to ferment a beverage containing apples, pears, and carrots. The metabolites and antioxidant activities were examined during the fermentation process. Results showed that lactic acid and acetic acid accumulated gradually, whereas malic acid decreased. Glucose and fructose increased from 0.48 and 14.8 g/L to 7.7 and 20.8 g/L, respectively, while sucrose decreased slightly. Ascorbic acid also increased continuously during the fermentation to 90.74 mg/100 mL. DPPH and ABTS radical scavenging activity and FRAP reached their maximum value after 4–8 days. The accumulation of TPC, TFC, and SOD reached their maximum value on the 8th day of fermentation. Our study revealed that the L. plantarum-fermented vegetable–fruit beverage showed significant antioxidant activity, which is helpful in evaluating the fermentation end-point and developing a high-quality fermented beverage.     

Study of the Effect of High Hydrostatic Pressure (HHP) on the Osmotic Dehydration Mechanism and Kinetics of <Emphasis Type="Italic">Wumei</Emphasis> Fruit (<Emphasis Type="Italic">Prunus mume</Emphasis>)

Osmotic dehydration (OD) is the most important procedure for obtaining candied wumei (Prunus mume), which is a very popular snack in Eastern Asian countries. This study aims to evaluate the effects of high hydrostatic pressure (HHP) pre-treatment (50–400 MPa) on the mass transfer kinetics and on the water diffusivity of wumei fruit during OD and to investigate the effect on water distribution and cell viability aspects. The results showed that HHP increased initial rate and effective diffusivity of mass transfer values compared to non-treated samples. Time domain nuclear magnetic resonance revealed that, upon HHP treatment, the water redistributed in vacuole, cytoplasm/extracellular spaces, and cell wall/membrane. The application of 400 MPa probably caused some irreversible damages to the cell membranes. The cell viability study determined by fluorescein diacetate staining showed a loss of cell viability at pressures higher than 200 MPa. HHP exhibited an effective pre-treatment to increase mass transfer of wumei fruit during OD process.     

Optimization of recombinant <Emphasis Type="Italic">Zea mays</Emphasis> transglutaminase production and its influence on the functional properties of yogurt

The requirements for the production of optimized Zea mays transglutaminase (TGZo) using Pichia pastoris GS115 (pPIC9K-tgzo) were optimized in this study. Plackett–Burman design was used to screen variables that significantly influence TGZo production. Oleic acid, methanol, and loading volume were identified as the most significant parameters. Central composite design was employed to determine the optimal level of these three parameters for TGZo production. Results showed that 1078 mU/mL of TGZo activity and 7.6 mg/L of TGZo production were obtained under conditions of 0.07% oleic acid, 1.31% methanol, and 7.36% loading volume. To explore the functional characteristics of TGZo, it was used in yogurt. It was found that the addition of TGZo could produce yogurt with stronger acid gel and higher consistency, cohesiveness, index of viscosity, and apparent viscosity than the untreated product. Therefore, TGZo can be used as a substitute for microbial transglutaminase in the yogurt, even in the food industry.     

Antimicrobial Activity of Binary and Ternary Mixtures of Vanillin,Citral, and Potassium Sorbate in Laboratory Media and Fruit Purées

The susceptibility of Escherichia coli, Salmonella enteritidis, Saccharomyces cerevisiae, and Zygosaccharomyces bailii to binary and ternary mixtures of potassium sorbate (KS), vanillin (V), and citral (C) was evaluated according to the Berenbaum experimental design, in laboratory media. For some V/C combinations, KS inhibitory concentrations were determined in agarized melon and mango purées by the spiral gradient endpoint (SGE) method. In laboratory media, inhibitory antimicrobial combinations were generally additives. For the yeasts, some synergistic effects were observed. All Berenbaum mixtures which resulted inhibitory in laboratory media were confirmed in the fruit purées. When the SGE method was used, several inhibitory ternary mixtures were found. The lowest inhibitory KS concentrations, estimated for a given V/C combination, corresponded to the bacteria assayed in melon purée. Z. bailii was not inhibited at any condition. Some synergistic antimicrobial combinations (595 ppm V + 251 ppm C + 8 ppm KS in melon and 280 ppm V + 123 ppm C + 8 ppm KS in mango purées) could be useful to achieve a desired inhibitory effect in fruit purées while reducing their concentrations.     

Inactivation Kinetics of the Most Baro-Resistant Enzyme in High Pressure Processed Litchi-Based Mixed Fruit Beverage

This work focused on a litchi-based mixed fruit beverage, comprising of coconut water and lemon juice, mixed in an optimized proportion. Based on preliminary studies, three resistant spoilage enzymes were identified in the beverage, viz. polyphenol oxidase (PPO), peroxidase (POD), and pectin methyl esterase (PME). The response surface methodology (RSM) based on central composite face-centered design (FCCD) screened out PPO as the most resistant enzyme within the high pressure processing (HPP) domain of 200–600 MPa/30–70 °C/0–20 min. A detailed kinetic study was conducted on PPO inactivation within the same HPP domain along with a set of thermal treatments (0.1 MPa/30–70 °C). A synergistic effect of pressure and temperature on PPO inactivation was observed, throughout the HPP domain. However, PPO was almost completely inactivated at 500 MPa/70 °C/20 min. The inactivation order (n) values for PPO were 1.10 and 1.25 for thermal and HPP treatments, respectively. For every 10 °C rise in temperature, the inactivation rate constant (k, U^n-1 min^?1) increased approximately by 1.5 times, within 50–70 °C (at 0.1 MPa), while a 10-fold increase was obtained in the case of HPP treatments. The activation energy (E _a ) and the activation volume (V _a), depicting the temperature and pressure dependence of k, was found to decrease slightly, with an increase in pressure and temperature, respectively. The PPO inactivation rate constant was modeled as a function of both temperature and pressure conditions by combining both Arrhenius and Eyring equations.     

Physiochemical properties and probiotic survivability of symbiotic oat-based beverage

The objectives of this study were to develop a symbiotic oat-based beverage (SOB) and to analyze its physiochemical properties and the probiotic survivability. The beverage base was prepared by fermenting a mix containing oat flour (10%, w/w), sugar (4%, w/w), and inulin (1%, w/w) with a commercial Lactobacillus plantarum (0.003%, w/w) at 30 °C for 12 h. The SOB was formulated using the fermented oat base, sugar, stabilizers (pectin and λ-carrageenan), vitamin C, and citric acid. The beverage was analyzed for total solids (11.65 ± 0.22%), protein (0.58 ± 0.02%), fat (0.37 ± 0.02%), carbohydrate (10.70 ± 0.33%), ash (0.14 ± 0.01%), and dietary fiber (0.70 ± 0.05%). The pH value of the beverage was stable at about 3.60 during 7-week storage. Lactobacillus plantarum population in the beverage remained above 10⁷ CFU/g throughout the storage. Oat-based beverage is a low fat and high dietary fiber symbiotic food.     

Production,nutritional and biological value of bambara groundnut (<Emphasis Type="Italic">Vigna subterranea</Emphasis>) milk and yoghurt

The purpose of this study was to assess the nutritional properties of Bambara milk and yoghurt. The milk was produced by aqueous extraction of flour obtained by dehulling the seeds followed by parboiling. It was then fermented using a mix culture of L. Bulgaricus, S. thermophilus and L. plantarum, followed by the evaluation of the protein biological value on rats. During the process of flour production, from the whole seeds to the flour, a significant drop in total polyphenol content (1.00?±?0.10–0.41?±?0.01 mg/100 g) and phytates (1.18?±?0.03–0.32?±?0.01 mg/100 g) was observed while the protein content increased (19.7?±?1.2–25.47?±?2.28 g/100 g). During the fermentation of the milk into yogurt, a significant decrease in phytate content (0.29?±?0.01–0.03?±?0.01 g/100 g), an increase in the protein content (1.8?±?0.1–2.6?±?0.1 g/100 g) and the protein digestibility (91.5–96%) were equally observed. Red blood cell, glycaemia, the ASAT and ALAT contents of rat bloods fed Bambara milk or yoghurt were not significantly different to rats fed casein as protein reference. In conclusion Bambara groundnut is a source of protein which the quality may be enhanced through processing of high value yogurt.     

Inactivation of <Emphasis Type="Italic">Salmonella enterica</Emphasis> in a Rice Beverage by Ultrasound: Study of the Parameters Affecting the Antibacterial Effect

The topic of this paper is the investigation of the antibacterial effect of ultrasound (US) towards Salmonella enterica in a rice beverage. The beverage was inoculated at different levels (8 and 5 log CFU/mL) and US-treated; then, a challenge test under refrigeration was carried out. The maximum net power of the equipment was 130 W; the treatment was carried out at 40–100% of the net power, for 2–10 min; the pulse was set to 2–10 s. For both the inoculum levels, power and time were the most important factors for the antimicrobial effect towards S. enterica. The combinations resulting in the highest inactivation of the pathogen were tested during the challenge test at 4 °C, and in some combinations, S. enterica remained below the detection limit for 13 days.     

Persimmon fruit enhanced quality characteristics and antioxidant potential of beer

Various adjuncts, including fruits, are added for flavoring beer, one of the most famous beverages in the world. The influence of persimmon fruit on antioxidant activities and quality characteristics of beer was investigated in this study. The antioxidant activities measured through DPPH and superoxide and hydroxyl anions scavenging potentials as well as total polyphenol contents of the persimmon-treated beer were significantly (p < 0.05) high compared to the control. The mineral elements Mg, K, and Ca were also significantly (p < 0.05) increased, however toxic heavy metals were not detected in the persimmon beer. Among the persimmon beer samples, the overall acceptance value was significantly (p < 0.05) high when the beer was prepared by adding 150 g of the fruit in 10 L of water. The results suggested that an addition of 150 g of persimmon fruit per 10 L of water could better enrich the nutritional, organoleptic, and antioxidant potentials of beer.     

Green Approach for Sample Preparation and Determination of Anthocyanins from <Emphasis Type="Italic">Lycium ruthenicum</Emphasis> Murr. Using a <Emphasis Type="Italic">β-</Emphasis>Cyclodextrin-Based Extraction Method Coupled with UPLC-DAD Analysis

This study aimed to develop and optimize a β-cyclodextrin (β-CD)-based technique for extracting anthocyanins from Lycium ruthenicum Murr. and to establish a ultra-high-performance liquid chromatography-diode array detector (UPLC-DAD) method for their analysis. β-CD solutions produced higher extraction yields of petunidin-3-O-(trans-p-coumaroyl)-rutinoside-5-O-glucoside and total anthocyanins from L. ruthenicum fruit than did pure water and aqueous hydroxypropyl-β-cyclodextrin (HPβ-CD) and ethanol and methanol solutions. Extraction at 50 °C for 30 min using 1.65% β-CD solution and a liquid/solid ratio of 15:1 produced the optimal extraction yield of L. ruthenicum anthocyanins. A UPLC-DAD method was developed for the determination of L. ruthenicum anthocyanins using an ethanol-based mobile phase, and the primary anthocyanins were identified using two-dimensional LC-MS/MS. Method validation showed that the developed method was accurate, stable, and reliable for the analysis of petunidin-3-O-(trans-p-coumaroyl)-rutinoside-5-O-glucoside and total anthocyanins from L. ruthenicum fruit. The present study showed that β-CD-based extraction coupled with UPLC-DAD analysis is an efficient and green method for the extraction and analysis of anthocyanins from L. ruthenicum fruit.     

Value Addition of Greek Yogurt Whey Using Magnetic Fluid and Sepiolite Treatments

Magnetic fluid treatment (MFT) and the addition of a magnesium hydrosilicate clay mineral, sepiolite, were evaluated as physical cost-effective methods to add value to Greek yogurt whey (GYW), a co-product of Greek yogurt manufacturing. Three separate batches of GYW were obtained from two US Greek yogurt manufacturers. A GYW sample was collected from each batch, adjusted to a pH of 7.2, and re-circulated for 5 min through a pumping system at a rate of 7.5 L/min with or without exposure to a 0.6 Tesla permanent magnetic field. The sample was split into thirds, heated to 80 °C, and then sepiolite was added at one of three levels: 0, 2, or 4 g of sepiolite per 100 g GYW. After centrifugation at 1000g for 5 min, samples formed a top aqueous and a bottom sediment layer. Top aqueous layers were analyzed for total solids, ash, lactose, protein, calcium, phosphates, and sodium contents along with color. MFT did not feasibly affect the analyzed GYW components from both manufacturers. Protein within the top aqueous layers compared to GYW significantly decreased about 60 % for manufacturer 1 and 45 % for manufacturer 2 with either amount of sepiolite treatment. The color values b* and a* in the GYW from both manufacturers significantly decreased with the addition of sepiolite by about 70 and 90 %, respectively. MFT in the present study was not a practical treatment method for de-mineralizing GYW. However, sepiolite was found to have possible applications in the removal of proteins, phosphates, and natural color pigments in GYW.     

Dispersive Liquid–Liquid Microextraction Combined With Micellar Electrokinetic Chromatography for the Determination of Some Photoinitiators in Fruit Juice

A fast and simple technique composed of dispersive liquid–liquid microextraction (DLLME) and micellar electrokinetic chromatography (MEKC) with diode array detector (DAD) was developed for the determination of multi-photoinitiators in fruit juice. Seven photoinitiators were separated in MEKC using a 25 mM borate buffer of pH 8.0, containing 24 mM sodium dodecyl sulfate (SDS), 10 mM β-cyclodextrin (β-CD), and 12.5 % acetonitrile (v/v). A CD-modified MEKC made this method more suitable for the determination of isopropylthioxanthone (ITX) isomers including 2-IXT and 4-ITX than the recently prescribed methods. A DLLME procedure was used as an offline preconcentration strategy. The satisfactory recoveries obtained by DLLME spiked at two spiked levels ranged from 85.6 to 124.7 % with relative standard deviations (RSDs) below 14 %. The limits of quantification (LOQs) ranged from 2.1 to 6.0 μg kg^?1.     

Effect of sodium selenite on the bacteria growth,selenium accumulation,and selenium biotransformation in <Emphasis Type="Italic">Pediococcus acidilactici</Emphasis>

In this study, the effect of low selenium concentrations on bacteria growth, selenium bioaccumulation, and selenium speciation in Pediococcus acidilactici was investigated. Six different sodium selenite (Na₂SeO₃) solutions with concentrations of 0, 0.5, 1, 2, 3, and 4 mg/L were added in MRS broth for 24 h. Then, the obtained bacterial pellets were weighed. The contents of total selenium and selenium species in the bacterial pellets were measured via optimized enzymatic hydrolysis and HPLC-ICP-MS. The maximum dried P. acidilactici biomass of 1.44 g/L was achieved by utilizing 1 mg/L Na₂SeO₃. By increasing sodium selenite concentrations, total selenium contents were significantly increased from 0.14 to 1.45 mg/g dry weight (p < 0.05). The findings indicated that selenium was favorably incorporated into the bacteria protein fraction and mainly formed selenocysteine. Therefore, selenium-enriched lactic acid bacterium P. acidilactici can deliver a less-toxic, more bioavailable selenium source for human and animal nutrition.     

Simultaneous Detection of Azodicarbonamide and the Metabolic Product Semicarbazide in Flour by Capillary Electrophoresis

In the present work, capillary electrophoresis (CE) was used for the first time for the simultaneous analysis of azodicarbonamide (ADA) and semicarbazide (SEM), and the capillary electrophoresis separation conditions, extraction agents, and derivatization conditions were investigated. In 20 mmol L^?1 sodium tetraborate, 30 mmol L^?1 β-cyclodextrin (β-CD), 17 % isopropanol (v/v), and 25 mmol L^?1 sodium dodecyl sulfate (SDS) running buffer, ADA and SEM previously derivatized with 9-fluorenylmethyl chloroformate (FMOC) were separated in less than 25 min with good sensitivity. The linear ranges were 8.3?×?10^?4～6.6?×?10^?2 mmol L^?1 and 1.9?×?10^?3～3.4?×?10^?2 mmol L^?1, and detection limits (S/N?=?10) were 0.5 and 0.15 mg kg^?1 for ADA and SEM, respectively. The proposed method was successfully applied for the simultaneous analysis of ADA and SEM in five flour samples with satisfactory recovery data from 88.0 to 93.0 % for ADA and 98.0 to 106.0 % for SEM, indicating the valuable potential application of this method for food analysis.     

Comparative inactivation studies of <Emphasis Type="Italic">Aegle marmelos</Emphasis> (<Emphasis Type="Italic">bael</Emphasis>) peroxidase in crude extract of fruit by heat processing and ultrasonication treatment

Bael (Aegle marmelos) is considered as a holy fruit comprised of vast number of phytonutrients. Whole bael tree including all its parts has medicinal significance. Lack of awareness and seasonal nature makes its processing rather challenging. Conventional heat processing may lead to inactivation of quality hampering enzymes such as peroxidase, but at the cost of loss in essential phytonutrients. In the present work it was observed that thermal inactivation of bael peroxidase obeyed first order kinetics with enzyme activation energy of 7.7 kJ mol^?1. Complete inactivation of bael peroxidase was achieved within 11 min at 85?°C while ultrasound treatment attained in lesser time of 4 min at 64.07 W cm^?2 ultrasonic intensity. Loss of marmelosin a well-known phytonutrient in bael fruit was found to be 83.29?% by heat (11 min, 85?°C) and only 50.20?% by ultrasonication (4 min, 64.07 W cm^?2 ultrasonic intensity). Ultrasonication has potential to overcome harmful effects of heat processing with retention of phyto-constituents and hence has promising future in various food processing applications.     

Quantification and Concentration of Anthocyanidin from Indian Blackberry (Jamun) by Combination of Ultra- and Nano-filtrations

Indian blackberry (Syzygium cumini) is an excellent source of antioxidants and anthocyanins. The fruit juice can be concentrated by membrane filtration for use as nutritional supplements. The juice was extracted and clarified by ultrafiltration (50 kDa) and concentrated by nano-filtration (300 Da). Physicochemical properties of permeate and retentate were analysed. Protein, polyphenol and antioxidant contents were determined by spectrophotometric method. Anthocyanidins were quantified by RP-HPLC-photodiode array detector method. The nano-filtered concentrate had various anthocyanidins such as cyanidin chloride (5.9 mg/10 g), malvidin chloride (20.8 mg/10 g) and delphinidin chloride (3.6 mg/10 g). Rejection rates of protein, polyphenol and antioxidants for ultra- and nano-filtered permeates were 48%, 22.3%, 51% and 63%, 74%, 40%, respectively. The particle size distribution of the concentrated juice followed a parabolic curve justifying proper filtration. The results suggest possible use of the fruit juice concentrate in beverage and pharmaceutical industry.     

气相色谱法测定蜜饯中甜蜜素含量的不确定度评定

目的评定气相色谱法测定蜜饯中甜蜜素含量的不确定度。方法通过建立不确定度数学模型,根据GB 5009.97-2016《食品中环己基氨基磺酸钠的测定》气相色谱法测定蜜饯中甜蜜素含量,分析该方法测量不确定度的主要来源,幵评定了各标准不确定度的分量。结果在蜜饯中的甜蜜素含量测定中,当样品的甜蜜素含量为8.91 g/kg,其扩展不确定度为0.631 g/kg (k=2),结果表示为(8.9±0.6) g/kg。结论本研究掌握了引入不确定度的因素,通过降低可控不确定度来提高测量的准确度,该质量控制手段可用于合理的体现测定结果的可靠程度。     

Dielectric Properties of Yogurt for Online Monitoring of Fermentation Process

Yogurt is one of the most popular dairy products fermented by Lactobacillus bulgaricus and Streptococcus thermophilus. The present study introduced dielectric properties as a new technique for yogurt fermentation monitoring. Dielectric properties of cow milk and yogurt at different time of fermentation were measured from 10 to 3000 MHz at 42 °C using open-ended coaxial-line probe technology by an impedance analyzer. Meanwhile, pH and titratable acidity of yogurt at different fermentation time were measured. Results showed that the dielectric loss factor of yogurt was positively correlated with fermentation time and had an irregular change at the endpoint of fermentation (7 h, pH?≈?4.6). The polynomial determination coefficients of dielectric loss factor with pH and titratable acidity decreased with increasing frequency and were found highest at 10 MHz (0.927 and 0.963, respectively). The linear coefficients of determination between measured values and calculated values were 0.990 for titratable acidity and 0.965 for pH at 10 MHz, respectively. Accordingly, dielectric loss factor can be a promising indicator for online monitoring of industrial yogurt fermentation process.     

果梅蜜饯中铝的污染来源分析及控制措施

目的 了解以果梅为原料生产的蜜饯中铝污染来源和水平, 探寻蜜饯中铝污染的关键环节。方法 采集生产企业加工用的原料、辅料、添加剂、加工过程中半成品及成品等样本, 利用电感耦合等离子体质谱法(inductively coupled plasma mass spectrometry, ICP-MS)测定其中铝含量, 采用SPSS 26.0对其中铝残留量进行统计分析, 提出相应的铝污染控制措施。结果 加工用辅料、添加剂、生产用水中铝残留量较低, 83份果梅本底铝含量范围为17.54~156.32 mg/kg, 平均值为(44.99±23.28) mg/kg, 中位数为38.00 mg/kg, 超过50 mg/kg的样本占比24.1% (20/83)。盐腌制、糖腌制加工对样本中铝残留量差异有统计学意义(P<0.05), 不同场所加工的雕梅中铝残留量差异有统计学意义(Z=-2.005, P=0.045), 不同类别蜜饯中铝残留量差异有统计学意义(H=12.718, P=0.005)。结论 果梅原料中含有一定量本底铝值, 盐腌制加工可能是话化类蜜饯中铝污染的主要来源, 糖腌制加工降低了蜜饯中铝的残留量, 使用含铝添加剂可能是糖腌制蜜饯中铝的主要来源, 开展蜜饯中铝污染来源调查和风险防控时, 建议加强对相应环节的控制, 减少蜜饯中铝污染的来源。