Effect of industrial juice concentrate processing on phenolic profile and antioxidant capacity of black carrots

Black carrot concentrate has gained increasing interest in recent years as a natural colourant due to its substantial content of bioactive compounds, especially anthocyanins. Black carrot concentrate production includes several steps, some of which are milling, mashing, pressing, pasteurisation and concentration. In this study, every step of black carrot concentrate processing was investigated to elucidate both the quantitative and qualitative changes in antioxidative compounds using spectrophotometric, HPLC‐based and LC‐QTOF‐MS‐based analyses. The results obtained indicated that processing the raw black carrot material into its concentrate led to an overall reduction of 70%, 73% and 44% in total phenolic, total flavonoid and total monomeric anthocyanin contents on a dry weight basis, respectively. Moreover, concentrate processing resulted in 67% and 71% decreases in total antioxidant capacity, determined using DPPH and CUPRAC methods, respectively, on dry weight basis. Untargeted LC‐MS‐based metabolomics analysis enabled the identification of ten phenolic components including seven anthocyanins and three phenolic acids. HPLC‐based quantification of individual anthocyanins revealed cyanidin‐3‐xylosyl (feruloylglucosyl)galactoside as the major anthocyanin component.     

胡萝卜多糖硫酸酯化修饰及其抗氧化活性研究

采用水提醇沉法提取胡萝卜粗多糖,经Sevage法与木瓜蛋白酶相结合法除蛋白后,以DEAE纤维素柱层析分离纯化得到具有抗氧化活性的多糖组分。用浓硫酸法对其进行硫酸酯化修饰,经红外光谱比和硫酸钡比浊法定性定量分析多糖酯化率。研究结果表明:当硫酸取代度为18.4%,即硫酸酯化率为2.94时硫酸酯化胡萝卜多糖的抗氧化活性比未修饰多糖增加1.5倍。     

Effect of thermal and non-thermal processing on antioxidant potential of cowpea seeds

Legumes are a good source of bioactive components, besides being nutrient dense. These components have antioxidant properties and have a protective role against free radicals. Legumes like cowpeas are usually consumed after certain processing, so the present study was intended to assess antioxidant property of selected four cultivars of cowpea after going through various thermal (autoclaving, microwave, boiling, and roasting) and non-thermal (soaking and fermentation) processings. Thermal processing reduced total phenolic content (TPC), total flavonoid content (TFC), and ferric reducing antioxidant power (FRAP) in all cultivars with respect to antioxidant activity of raw cultivars, while DPPH scavenging activity increased after all thermal treatments excluding few thermal processings. Non-thermal processing revealed increase in TPC, DPPH scavenging activity, and FRAP values, while TFC content showed a decreasing trend. A moderately high correlation between TPC and DPPH scavenging activity was observed in both kinds of thermal treatments indicating the role of phenolic compounds for antioxidant activity. It was concluded from the study that fermentation processing has promising effects on retention and enhancement of antioxidant activity of cowpea cultivars.     

番茄红素热异构化机制及其影响因素研究进展

番茄红素是来自植物性食物中最重要的类胡萝卜素之一,它具有抗氧化、预防前列腺癌和心血管疾病的功 能。生鲜植物性食品中的番茄红素主要为全反式构型,但研究表明全反式番茄红素的生物活性和生物利用率不及其 顺式异构体。因此,利用食品加工技术（光照、加热、氧化、改变pH值、添加表面活性剂）促进食品中番茄红素 的异构化对提升产品营养品质具有重要意义,其中热处理是最方便、最经济的方式。本文在论述番茄红素热异构化 作用机制的基础上,分别对模拟体系和食物体系中的番茄红素热异构化的影响因素（溶剂种类、加热温度、加热时 间等）进行探讨,并得出溶剂种类和食物基质对番茄红素热异构化影响较大,提高温度或延长加热时间可促进番茄 红素异构化甚至使其发生降解的结论。最后提出了该领域研究中存在的问题及今后的研究方向。     

Lycopene in tomatoes: chemical and physical properties affected by food processing

Lycopene is the pigment principally responsible for the characteristic deep-red color of ripe tomato fruits and tomato products. It has attracted attention due to its biological and physicochemical properties, especially related to its effects as a natural antioxidant. Although it has no provitamin A activity, lycopene does exhibit a physical quenching rate constant with singlet oxygen almost twice as high as that of beta-carotene. This makes its presence in the diet of considerable interest. Increasing clinical evidence supports the role of lycopene as a micronutrient with important health benefits, because it appears to provide protection against a broad range of epithelial cancers. Tomatoes and related tomato products are the major source of lycopene compounds, and are also considered an important source of carotenoids in the human diet. Undesirable degradation of lycopene not only affects the sensory quality of the final products, but also the health benefit of tomato-based foods for the human body. Lycopene in fresh tomato fruits occurs essentially in the all-trans configuration. The main causes of tomato lycopene degradation during processing are isomerization and oxidation. Isomerization converts all-trans isomers to cis-isomers due to additional energy input and results in an unstable, energy-rich station. Determination of the degree of lycopene isomerization during processing would provide a measure of the potential health benefits of tomato-based foods. Thermal processing (bleaching, retorting, and freezing processes) generally cause some loss of lycopene in tomato-based foods. Heat induces isomerization of the all-trans to cis forms. The cis-isomers increase with temperature and processing time. In general, dehydrated and powdered tomatoes have poor lycopene stability unless carefully processed and promptly placed in a hermetically sealed and inert atmosphere for storage. A significant increase in the cis-isomers with a simultaneous decrease in the all-trans isomers can be observed in the dehydrated tomato samples using the different dehydration methods. Frozen foods and heat-sterilized foods exhibit excellent lycopene stability throughout their normal temperature storage shelf life. Lycopene bioavailability (absorption) can be influenced by many factors. The bioavailability of cis-isomers in food is higher than that of all-trans isomers. Lycopene bioavailability in processed tomato products is higher than in unprocessed fresh tomatoes. The composition and structure of the food also have an impact on the bioavailability of lycopene and may affect the release of lycopene from the tomato tissue matrix. Food processing may improve lycopene bioavailability by breaking down cell walls, which weakens the bonding forces between lycopene and tissue matrix, thus making lycopene more accessible and enhancing the cis-isomerization. More information on lycopene bioavailability, however, is needed. The pharmacokinetic properties of lycopene remain particularly poorly understood. Further research on the bioavalability, pharmacology, biochemistry, and physiology must be done to reveal the mechanism of lycopene in human diet, and the in vivo metabolism of lycopene. Consumer demand for healthy food products provides an opportunity to develop lycopene-rich food as new functional foods, as well as food-grade and pharmaceutical-grade lycopene as new nutraceutical products. An industrial scale, environmentally friendly lycopene extraction and purification procedure with minimal loss of bioactivities is highly desirable for the foods, feed, cosmetic, and pharmaceutical industries. High-quality lycopene products that meet food safety regulations will offer potential benefits to the food industry.     

Thermally-induced geometrical isomerisation of lycopene and its potential influence on functional activity

About 90–98% of native lycopene exists in the all-E form, but 79–88% of the lycopene found in the human body are Z-isomeric forms. Thermally-induced geometrical isomerisation of lycopene occurred within 24 h of refluxing in ethyl acetate and the proportion of Z-isomers increased from 5.8% to 49.9%. Accordingly, the concentration of lycopene required to double quinone reductase (QR) activity in Hepa 1c1c7 cells decreased from >100 to ∼22 μg/mL following thermo-isomerisation, while cell viability was retained at >87% at levels up to 50 μg/mL. The inhibition of nitric oxide (NO) production in activated RAW 264.7 macrophages was 50% at ∼100 μg/mL thermo-isomerised lycopene and increased to >80% when the concentration in the medium was increased to 500 μg/mL. No significant inhibition of NO evolution by macrophages occurred with native (∼94% all-E) lycopene. Both QR induction and NO inhibition bioassays revealed that the structural changes evoked by thermo-isomerisation were accompanied by enhanced biological functionality.     

Thermal stability of antiparasitic macrocyclic lactones milk residues during industrial processing

The chemical stability of residues of different antiparasitic macrocyclic lactone compounds in milk subjected to thermal treatment was assessed. Concentrations of ivermectin (IVM), moxidectin (MXD) and eprinomectin (EPM) in sheep milk, equivalent to those measured in vivo in milk excretion studies, were subjected to 65°C over 30 min or to 75°C for 15 s. Residue concentrations of IVM, MXD and EPM in milk were measured by high-performance liquid chromatography (HPLC) (fluorescence detection) before and after heat treatment of the drug-fortified milk samples. No evidence of chemical loss was obtained in either of the thermal treatments under evaluation. The stability of the parent compounds in milk was evidenced by the lack of bioconversion products (metabolites) after both thermal treatments. Only very minor changes on drug concentrations were observed at the end of the treatments, which fell within the limits of the variation of the validated analytical method. In conclusion, residue concentrations of macrocyclic lactones are unaffected by industrial-simulated milk thermal procedures. Based on the reported findings, it can be postulated that residue concentrations of IVM, MXD and EPM measured in raw sheep milk may be used to estimate consumer exposure and dietary intake for these veterinary drugs.     

热处理增加总抗氧化剂活性提高番茄营养价值

人们长久以来一直认为加工后的果蔬因Vc损失而导致其营养价值低于新鲜果蔬。而通过我们的研究发现苹果中Vc对总的抗氧化剂活性的贡献率小于0.4%,而大部分该活性来自于植物活性物质的结合,这意味着尽管有Vc损失,但加工过的果蔬还能保留其抗氧化剂活性。结果表明,尽管有Vc损失,热处理提高了总的抗氧化剂活性和番茄中生物可利用番茄红素含量,并且没有引起总酚类和总类黄酮含量的显著变化,从而提高了番茄的营养价值。     

Chemical composition and oxidative stability of Tunisian monovarietal virgin olive oils with regard to fruit ripening

The chemical composition of virgin olive oil may be influenced by genotype and different agronomic (i.e. fruit ripeness degree, water supply) and technological factors. This article reports the evaluation of the influence of the olive ripening stage on the quality indices, the major and the minor components and the oxidative stability of the two main monovarietal Tunisian cultivars (cvv. Chétoui and Chemlali) virgin olive oils. Moreover, the olives cv. Chétoui were tested in a rain-fed control and an irrigation regime. The oils sampled at five different ripeness stages were submitted to liquid chromatographic determination (HPLC-DAD/MSD) of their quali-quantitative phenolic and tocopherolic profiles. Moreover, the triacylglycerol and fatty acid compositions, and minor components such as squalene, pigments and their relation with the oil oxidative stability were evaluated. The tested oils showed very good correlation between the oxidative stability and the concentrations of total phenols, practically secoiridoids and α-tocopherol.     

Optimisation of convective drying of carrots using selected processing and quality indicators

The effect of drying temperature (40–65 °C) and air rate (2–6 m s^?1) on the formation of Maillard reaction indicators and vitamins content of carrots dehydrated by convection has been investigated. The range of assayed processing conditions, based on a previous central composite face design (CCD), led to moderate changes in the studied parameters, even under the most severe conditions. In addition, the drying kinetic of the process was studied taking into account the experimental quantitation of shrinkage, which allowed the determination of a first drying period with a constant rate of water evaporation per unit of exchange surface. The slope of the first drying period, the moisture loss during the first hour of drying and the level of quality parameters (Maillard reaction indicators and vitamins) were correlated with processing conditions with high accuracy. For the prototype here used, the optima temperature and air rate to maximise the desirability function (0.77) were 46 °C and 4.9 m s^?1.     

Phenolic contents,antioxidant activities and potential bioaccessibilities of industrial pomegranate nectar processing wastes

Antioxidant potential and bioaccessibility of co‐products from industrial pasteurised pomegranate nectar (PN) processing such as peel (PP), press cake (PC) and precipitate after clarification (PAC) in comparison with raw material (arils) and final products (CON and PN) were determined. Total phenolic (TPC), flavonoid (TFC), anthocyanin (TAC), tannin contents (TTC) and antioxidant activity (TAA) were determined besides identifying major phenolics and investigating in vitro bioaccessibility after gastrointestinal (GI) digestion. PP showed the highest values, except for TAC. Phenolics (12.7–43.0%) were found to be more stable than anthocyanins (0.6–2.1%) after in vitro GI digestion. PAC was found to be a better source for anthocyanins than CON and also showed higher phenolic bioaccessibility (28.8%) than PN (19.6%). PC and PAC possessed as much TPC, TFC, TTC and TAA levels as CON, with some exceptions. Therefore, these results indicated that not only PP but also PC and PAC should be valorised as a good source for phenolics and anthocyanins.     

Multiple regression models and Computer Vision Systems to predict antioxidant activity and total phenols in pigmented carrots

The relationships between colour parameters obtained by a Computer Vision System (CVS) and both antioxidant activity (AA) and total phenol contents (TP) on coloured carrots were expressed as multivariate models obtained by multiple linear regression. The AA and TP predicted by the proposed models showed a good correlation with the real AA (R² = 0.97, P ? 0.001) and TP (R² = 0.94, P ? 0.001) measurements on the data set including internal and external parts of carrots. The predictions on the data set including only the internal (unevenly pigmented) parts of the carrots exhibited lower determination coefficients (R² = 0.93 for AA and R² = 0.86 for TP, P ? 0.001). The effectiveness of the models was checked also on the colour information provided by a colorimeter whose measures proved to be more sensitive to the uneven pigmentation of the carrots. Finally, the proposed models were able to successfully estimate the AA and the TP contents of pigmented carrots when applied to colours measured by the CVS.     

加工温度对番茄和胡萝卜中类胡萝卜素含量的影响

目的:考察不同处理条件下,番茄和胡萝卜中类胡萝卜素含量的变化,指导人们采取合适的方法食用。方法:建立同时测定叶黄素、番茄红素和β-胡萝卜素的HPLC方法,测定常温、70℃和100℃时3种类胡萝卜素含量的变化。结果:在70℃时类胡萝卜素较稳定,温度达到100℃时则明显降解。结论:胡萝卜和番茄应熟食,以更好地吸收其营养成分,但加工温度应控制在70℃。     

番茄中番茄红素超声-微波辅助提取及其抗氧化活性研究

以番茄为原料,采用单因素分析结合正交设计试验的方法,研究番茄中番茄红素的超声-微波辅助提取工艺。同时,以合成抗氧化剂2,6-二叔丁基对甲酚(BHT)为阳性对照,采用清除1-1二苯基-2-苦肼基(DPPH·)法与羟自由基(·OH)法评价番茄中番茄红素抗氧化活性。结果表明:番茄中番茄红素超声-微波辅助提取的最佳工艺为:以体积比7∶1的乙酸乙酯-丙酮混合溶液为提取剂,料液比1∶17(g∶mL)超声温度50℃,微波功率325W,微波时间40s,超声时间40min。此工艺条件下,番茄红素提取率为1.293mg/g。番茄红素与BHT清除DPPH·的IC_(50)分别为8.78μg/mL与21.24μg/mL;清除·OH的IC_(50)分别为5.29μg/mL与16.63μg/mL,表明番茄红素具有很强的清除自由基能力,即具有很强的抗氧化活性。     

蛤蒌叶水提取物抗氧化活性的热稳定性研究

目的探究较高温条件下蛤蒌叶水提取物抗氧化活性的热稳定性。方法采用不同温度水浸提蛤蒌叶,检测不同温度提取物对DPPH及羟自由基清除能力,评估抗氧化活性,并定量其中总多酚、总多糖和总黄酮含量。结果蛤蒌叶水提物有较好的抗氧化能力,呈现浓度依赖性。当提取温度为50℃和80℃时,水提物分别对羟自由基和DPPH自由基有最强的清除能力。相应的IC_(50)值分别为(0.604±0.004) mg/mL、(0.314±0.002) mg/mL,其活性物质含量的变化与抗氧化能力的变化呈现出相关性,提取温度为80℃时,提取物中总黄酮、总多糖、总多酚有较高的含量,分别为24.91、232.07、34.98 mg/mL。结论蛤蒌叶水提物对2类自由基有最佳清除能力时的提取温度不同,其中对DPPH自由基清除活性具有一定的热稳定性,而对羟自由基的清除活性的热稳定性则较差。而总黄酮、总多糖、总多酚在80℃时能被充分提取,同时不受热分解。     

Thermal and high-pressure stability of purified polygalacturonase and pectinmethylesterase from four different tomato processing varieties

Polygalacturonase (PG) and pectinmethylesterase (PME) were extracted and purified from four tomato varieties (Galeón, Malpica, Perfectpeel and Soto) used in the processing industry. The processing stability (thermal and high pressure) of PG and PME from the four varieties was analyzed, and they all showed the same behavior. PG was present in two isoforms, PG1 (inactivated at 90 °C, 5 min) and PG2 (inactivated at 65 °C, 5 min). In contrast, PG1s and PG2s showed the same pressure stability, both can be inactivated at room temperature in the pressure range of 300–500 MPa. On the other hand, purified PMEs could be thermally inactivated (5 min, 70 °C) but 50% of its activity remained after high-pressure treatment (850 MPa, 15 min, 25 °C). High pressure processing can thus be used for selective inactivation of PG in tomato processing (while keeping PME intact). This fact could open prospectives for improving texture/rheology of processed tomato based products; however further research in the texture/rheology area is needed.