Papers by Francisco J. Heredia
Food Quality and Preference, 2007
This study was designed to assess the colour appearance of different wines. Four wine samples wer... more This study was designed to assess the colour appearance of different wines. Four wine samples were chosen: table red, oloroso, tawny port and rose ´. These wines were poured at different depths in Petri dishes and in cocktail glasses. All samples were assessed by a panel of eight observers in terms of lightness, colourfulness and hue. All samples were also measured using a tele-spectroradiometer and a digital camera. It was found that physical measurements agreed with visual estimates of lightness, colourfulness and hue. There is some discrepancy between observer hue and physical measurement hue for shallow oloroso. This greenish hue was demonstrated in this work as a physical effect. Tele-spectroradiometer and digital camera results can detect this effect and agreed well. The results showed that the digital non-contact measurement method can obtain fast and accurate results for describing colour appearance of liquid food products like wines studied here.
Lebensmittel-Wissenschaft & Technologie, 2016
Tomato products were analysed for their carotenoids and a-tocopherol contents to study the contri... more Tomato products were analysed for their carotenoids and a-tocopherol contents to study the contribution of individual compounds to the antioxidant capacity and assess the existence of interactions. Besides, the applicability of reflectance measurements for the estimation of the Trolox Equivalent Antioxidant Capacity (TEAC) was explored. Statistically significant regression coefficients were found between TEAC values and carotenoids and a-tocopherol levels. Lycopene seemed to have the highest contribution, followed by phytofluene. The results showed that the antioxidant capacity of phytofluene warrants further investigation. It was observed that there can be interactions between lycopene and atocopherol, although just the lycopene/a-tocopherol ratio cannot be used to predict the kind of interaction. More knowledge of these interactions would supply new tools for the industry to develop more optimized ingredients. Finally, the lycopene levels and TEAC values can be estimated by considering reflectance readings at certain wavelengths, which is important for field and quality control applications.
Foods, 2021
Overripe seeds from sun-dried grapes submitted to postharvest dehydration constitute a scarcely i... more Overripe seeds from sun-dried grapes submitted to postharvest dehydration constitute a scarcely investigated class of vinification byproduct with limited reports on their phenolic composition and industrial applications. In this study, Raman spectroscopy was applied to characterize a selection of overripe seed byproducts from different white grapes (cv. Moscatel, cv. Pedro Ximénez and cv. Zalema) submitted to postharvest sun drying. The Raman measurements were taken using a 1064 nm excitation laser in order to mitigate the fluorescent effect and the dispersive detection scheme allowed a compactness of the optical system. Spectroscopic data were processed by a principal component analysis to reduce the dimensionality and partner recognition. The evolution of the Raman spectrum during the overripening process was compared with the phenolic composition of grape seeds, which was determined by rapid resolution liquid chromatography/mass spectrometry (RRLC/MS). A multivariate processing o...
Revista Mexicana de Ingeniería Química, 2020
del petróleo intemperizados en suelos y sedimentos (Biodegradation modeling of sludge bioreactors... more del petróleo intemperizados en suelos y sedimentos (Biodegradation modeling of sludge bioreactors of total petroleum hydrocarbons weathering in soil and sediments)
Journal of Food Science and Technology, 2017
This work includes the evaluation of 168 samples of raspberries 'Glen Lyon', representing whole m... more This work includes the evaluation of 168 samples of raspberries 'Glen Lyon', representing whole maturation period, by colorimetric and near infrared imaging techniques, as well as the quantification of total phenols, total anthocyanins and antioxidant activity by chemical methods. Samples showed significant differences depending on the maturation stage using CIELAB colour parameters and total anthocyanins content. The application of partial least squares regression allowed predicting the chemical features from image analysis data, with coefficients of determination (R 2 ) up to 0.75. The best prediction for total anthocyanins including colorimetric data was observed. The proposed methodology can be used as a reference method for assessing important quality attributes of raspberries. Moreover, it is useful, rapid and accurate automatic inspection method.
Food Chemistry, 2016
Oak chips-related phenolics are able to modify the composition of red wine and modulate the colou... more Oak chips-related phenolics are able to modify the composition of red wine and modulate the colour stability. In this study, the effect of two maceration techniques, traditional and oak chips-grape mix process, on the phenolic composition and colour of Syrah red wines from warm climate was studied. Two doses of oak chips (3 and 6 g/L) at two maceration times (5 and 10 days) during fermentation was considered. Changes on phenolic composition (HPLC-DAD-MS), copigmentation/polymerisation (spectrophotometry), and colour (Tristimulus and Differential Colorimetry) were assessed by multivariate statistical techniques. The addition of oak chips at shorter maceration times enhanced phenolic extraction, colour and its stabilisation in comparison to the traditional maceration. On contrast, increasing chip dose in extended maceration time resulted in wines with lighter and less stable colour. Results open the possibility of optimise alternative technological applications to traditional grape maceration for avoiding the common loss of colour of wines from warm climate.
Plant Growth Regulation, 2016
Solanum lycopersicum L. (tomato) is a very important fruit vegetable with high economic importanc... more Solanum lycopersicum L. (tomato) is a very important fruit vegetable with high economic importance and nutritional impact on the consumers worldwide. Moreover, tomato fruits are an important source of nutraceutical compounds. This work describes the physiological diversity affecting the ripening process that yields variation in fruit pigmentation with regard to anthocyanins compounds for one non-anthocyanin-accumulating (Ailsa Craig) and two anthocyanin-accumulating tomato genotypes (anthocyanin fruit type, low pigment accumulation, and Sun Black, high pigment accumulation). Using tomato fruits obtained by traditional breeding the present study reported modified hormone equilibrium at different ripening stages. This phenomenon can be considered as a consequence of the different pattern in the anthocyanins accumulation in fruits. Moreover, the fruit genotype showing the highest pigment accumulation appear more firm at the commercial stage. Overall, these results showed the considerable potential of exploiting natural genetic diversity to obtain tomatoes with higher levels of anthocyanins, and different quality traits such as colour and firmness.
Plant Foods for Human Nutrition, 2015
Roselle is a plant that accumulates anthocyanins significantly, hence its importance as food colo... more Roselle is a plant that accumulates anthocyanins significantly, hence its importance as food coloring and as a source of antioxidant compounds for human health. This study was aimed to determine phenolic composition and antioxidant capacity of methanolic extracts, and beverages obtained from native roselle cultivars in Mexico (Negra, Sudan, Rosa and Blanca) with different degrees of pigmentation, and to establish the color-composition relationship. Chromatographic methods were used to determine phenolic compounds: flavanols, flavonols, benzoic, hibiscus and phenolic acids as well as two main anthocyanins (cyanidin 3-sambubioside and delphinidin 3-sambubioside). The antioxidant capacity was evaluated by ABTS and FRAP assays. Tristimulus colorimetry showed to be a useful technique to determine the color-composition relationship, leading to equations that allowed to predict anthocyanin content of roselle (R > 0.84). Also, a stepwise linear discriminant analysis (SLDA) was developed in order to classify roselle cultivars. The obtained mathematical model could be an important tool to be used in colorimetric characterization of functional compounds used in food processing.
Journal of Agricultural and Food Chemistry, 2015
The combined effect of anthocyanin-flavanol-flavonol ternary interactions on the colorimetric and... more The combined effect of anthocyanin-flavanol-flavonol ternary interactions on the colorimetric and chemical stability of malvidin-3-glucoside has been studied. Model solutions with fixed malvidin-3-glucoside/(+)-catechin ratio (MC) and variable quercetin-3-β-D-glucoside concentration (MC+Q) and solutions with fixed malvidin-3-glucoside/quercetin-3-β-Dglucoside ratio (MQ) and variable (+)-catechin concentration (MQ+C) were tested at levels closer to those existing in wines. Color variations during storage were evaluated by differential colorimetry. Changes in the anthocyanin concentration were monitored by HPLC-DAD. CIELAB color-difference formulas were demonstrated to be of practical interest to assess the stronger and more stable interaction of quercetin-3-β-D-glucoside with MC binary mixture than (+)-catechin with MQ mixture. The results imply that MC+Q ternary solutions kept their intensity and bluish tonalities for a longer time in comparison to MQ+C solutions. The stability of malvidin-3-glucoside improves when the concentration of quercetin-3-β-D-glucoside increases in MC+Q mixtures, whereas the addition of (+)-catechin in MQ+C mixtures resulted in an opposite effect.
Optica Pura y Aplicada, 2014
In this work the colour of orange and mandarin juices from different varieties was evaluated by t... more In this work the colour of orange and mandarin juices from different varieties was evaluated by two instrumental methods: spectroradiometry and digital image analysis. The effect of the deepness and the background, and the validity of the colorimetric parameters obtained by both methodologies were explored to discriminate between groups. It was concluded that both methods allowed the discrimination between orange and mandarin juices, being spectroradiometry which provides the best classification.
Grasas Y Aceites, 2009
Optimización de la producción de una pasta de aceituna utilizando una propuesta metodológica basa... more Optimización de la producción de una pasta de aceituna utilizando una propuesta metodológica basada en el análisis sensorial y la medida objetiva del color.
Electronic Journal of Biotechnology, 2014
The properties of natural pigments, such as antioxidants, functional, medical, and nutraceutical,... more The properties of natural pigments, such as antioxidants, functional, medical, and nutraceutical, have demonstrated the advantages of these natural compounds over synthetic ones. Some products are accepted only when they are pigmented with natural, food-quality colorants: for example poultry products (manly marigold flower extracts). Carotenoids such as β-carotene, β-criptoxanthin and lutein are very attractive as natural food colorants due to their antioxidant and pro-vitamin activities which provide additional value to the target products. Marigold (Tagetes erecta) is an Asteraceous ornamental plant native to Mexico, and it is also important as a carotenoid source for industrial and medicinal purposes but nowadays its production is destined mainly for ornamental purposes. Results: Friable callus of T. erecta yellow flower (YF) and white flower (WF) varieties was induced from leaf explants on Murashige and Skoog (MS) medium supplemented with 9.0 μM 4-dichlorophenoxyacetic acid (2,4-D) and 8.8 μM benzyladenine (BA). Calluses developed from both varieties were different in pigmentation. Extract characterization from callus cultures was carried out by high-performance liquid chromatography (HPLC). This analytical process detected several carotenoids; the main pigments in extracts from YF callus were lutein and zeaxanthin, whereas in the extracts of the WF callus the main pigments were lutein, zeaxanthin, β-cryptoxanthin and β-carotene. Callus cultures of T. erecta accumulated pigments even after several rounds of subculture. Conclusions: WF callus appeared to be a suitable candidate as a source of different carotenoids, and tested varieties could represent an alternative for further studies about in vitro pigment production.
Journal of Food Composition and Analysis, 2015
Antioxidant capacity was evaluated by a cellular model (Saccharomyces cerevisiae) and chemical me... more Antioxidant capacity was evaluated by a cellular model (Saccharomyces cerevisiae) and chemical methods (FRAP, TEAC and total phenols by Folin-Ciocalteu assay) in the hydrophilic fraction (phenolic compounds and ascorbic acid) of orange juices (OJs) from six varieties (Midknight, Delta Seedless, Rohde Red, Seedless, Early and clone Sambiasi), harvested in two seasons. The contents of phenolic compounds and ascorbic acid analyzed, respectively, by UPLC and HPLC were 370.04 AE 76.97 mg/L and 52.05 AE 6.69 mg/100 mL. Variety and season significantly influenced (p < 0.05) composition and antioxidant capacity. TEAC and FRAP values correlated well with individual hydrophilic compounds (R 2 > 0.991) but no correlation with cellular assay was observed. An increase in survival rates between 23% and 38% was obtained, excepting for two varieties that showed no activity (Rohde Red and Seedless). Narirutin, naringin-d, ferulic acid-d 2 , didymin, neoeriocitrin and sinapic acid hexose and caffeic acid-d 1 were the phenolic compounds which contributed to survival rates (R 2 = 0.979, p < 0.01).
Journal of Food Engineering, 2012
ABSTRACT The Modified Uniform Oil Colour Scale (MUOCS) is proposed for the colour specification o... more ABSTRACT The Modified Uniform Oil Colour Scale (MUOCS) is proposed for the colour specification of virgin olive oils. MUOCS has 60 standard colours, the same number as the two previous scales available for the same purpose: Uniform Oil Colour Scale (UOCS) and Bromthymol Blue (BTB). A remarkable improvement in accuracy can be achieved from MUOCS standards: For a broad dataset of 1700 virgin olive oils produced in Spain during four different harvests, the average colour differences to the closest standards were 2.86, 3.99, and 8.17 CIELAB units using MUOCS, UOCS and BTB, respectively. A low-cost (&amp;lt;60 Euros) portable electronic device is proposed for the colour specification of virgin olive oils based on MUOCS and BTB standards. This device can operate with USB connection to a computer or AAA batteries, and is based on fast (&amp;lt;0.25 s) transmittance measurements of the virgin-olive-oil sample placed in a 5-mm pathlength quartz cell. The device may avoid the use of expensive laboratory instrumentation for colour measurement and can be easily employed by non-technician users. For a reduced set of commercial virgin olive oils with random colours, the MUOCS classifications provided by our device agreed with those given by conventional spectrophotometric measurements in 92% of the cases.
Journal of Agricultural and Food Chemistry, 2010
The stabilization of red wine color by the copigmentation phenomenon is a crucial process that do... more The stabilization of red wine color by the copigmentation phenomenon is a crucial process that does not always proceed favorably under natural conditions during the first stages of vinification. The impact of the prefermentative cold maceration technique on the phenolic composition and magnitude of the copigmentation level of organic Tempranillo wines elaborated in a warm climate have been studied as an enological alternative to the traditional maceration for obtaining highly colored wines. Tristimulus colorimetry was applied to study the color of wines during vinification, and a highperformance liquid chromatography (HPLC) procedure was used for the analysis of phenolic compounds. Spectrophotometric and colorimetric analyses were also performed to evaluate the copigmentation level of the wines. Significant chemical and color differences were found depending on the maceration technique applied. Prefermentative cold macerated wines were richer in those compounds accounting directly for the color of red wine (anthocyanins) and those involved in anthocyanin stabilization through copigmentation reactions (phenols), which was in accordance with the higher copigmentation degree and darker, more saturated and vivid bluish colors. The evaluation of the copigmentation based on colorimetric parameters in the CIELAB color space showed that prefermentative cold maceration caused greater effectiveness of copigmentation than traditional maceration since it induces more important and hence more easily perceptible color changes.
Journal of Agricultural and Food Chemistry, 2007
The phenolic composition (by HPLC-DAD-MS) and color characteristics (by Imaging Tristimulus Color... more The phenolic composition (by HPLC-DAD-MS) and color characteristics (by Imaging Tristimulus Colorimetry) of four strawberry cultivars that have shown good climate adaptation to subtropical area (Nikte, Zamorana, Jacona and Pakal) have been assessed. 24 monomeric phenolics were identified, including 15 anthocyanins, 5 phenolic acids, 1 flavanol and 4 flavonols. Nikte and Zamorana showed the highest phenolic potential mainly due to their higher content of anthocyanins, while Pakal was richer in phenolic acids. Regarding color, Nikte and Zamorana were the more similar cultivars having the lowest values of lightness and hue. On the contrary, the color of Pakal was quite different from all the rest, due to the specific distribution between pelargonidin and cyanidin. The inclusion of both phenolic and colorimetric information in the Linear Discriminant Analysis allowed reaching very good discriminations among cultivars.
Journal of the American Oil Chemists' Society, 2000
Twenty experienced observers with nondefective color vision judged 27 virgin olive oil samples wi... more Twenty experienced observers with nondefective color vision judged 27 virgin olive oil samples within an acceptable color range, using the bromthymol blue (BTB) method, under controlled observation conditions (daylight source with a correlated color temperature of 6500 K, and standard gray back‐ground). On the average, 44.8% of the observers agreed in their selections of the BTB standard solution matching a given oil sample, and this percentage increased to 88.2% considering ±one step in the two dimensions (pH and concentration) of the BTB scale. On the average, the lowest color difference between oil samples and available BTB solutions was 6.6 Commission Internationale de l'Éclairage 1976‐(L*a*b*) (CIELAB) units, but this color difference was approximately two times greater for the color difference between oil samples and BTB solutions selected by our observers. The colors of the BTB standard solutions in the CIELAB space are not uniformly distributed, and thus one step in pH o...
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Papers by Francisco J. Heredia