DSpace Angular :: Browsing by Author "Pedreschi, Franco"

Browsing by Author "Pedreschi, Franco"

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A non-destructive digital imaging method to predict immobilized yeast-biomass
(ELSEVIER, 2009) Acevedo, Cristian A.; Skurtys, Olivier; Young, Manuel E.; Enrione, Javier; Pedreschi, Franco; Osorio, Fernando
In food fermentation, many types of immobilization systems are used, such as hydrogel entrapment, where alginate is the main biopolymer. one of the important problems in industrial processes is the quantifications of biomass, since the traditional system of direct cell counting cannot be used. In this study, a simple digital imaging method to determine the biomass of yeasts immobilized into alginate capsules was developed. Important evidence of the yeasts growing inside the alginate was the change in the surface color of the capsule. Digital images were taken with different biomass concentration, and the RGB-analysis showed significant differences in the blue field. The histogram of the blue channel was used to develop a PLS multivariate calibration to predict biomass concentration. The method was validated in primary beer fermentation with good efficiency. (C) 2009 Elsevier Ltd. All rights reserved.
Analysis of Maillard reaction precursors and secondary metabolites in Chilean potatoes and neoformed contaminants during frying
(2024) Garcia-Rios, Diego; Hernandez, Ignacia; Alvaro, Juan E.; Pedreschi, Franco; Campos, David; Behn, Anita; Pedreschi, Romina
Southern Chile native potatoes are an interesting raw material to produce novel snacks like colored potato chips. These novel products should be comprehensively evaluated for the presence of undesirable compounds such as acrylamide, 5-hydroxymethylfurfural and furan, the main neoformed contaminants in starchy rich fried foods. This study evaluated the neoformed contaminant levels and oil content on chips made from eleven Chilean potato accessions and compared them with commercial samples. The neoformed contaminant contents were related to Maillard reaction precursor levels (reducing sugars and asparagine) and secondary metabolites (phenolic compounds and carotenoids). Neoformed contaminants correlated well among them and were weakly correlated with reducing sugars and asparagine. Acrylamide level in native potato chips ranged from 738.2 to 1998.6 mu g kg- 1 while from 592.6 to 2390.5 mu g kg- 1 in commercial samples. Thus, there is need to implement neoformed contaminant mitigation strategies at different steps of the production chain of colored potato chips.
Atmospheric immersion and vacuum impregnation of gallotannins and hydrolysed gallotannins from tara pods (Caesalpinia spinosa) mitigate acrylamide and enhances the antioxidant power in potato chips
(2024) Campos, David; Chirinos, Rosana; Huaraca-Espinoza, Paola; Aguilar-Galvez, Ana; Garcia-Rios, Diego; Pedreschi, Franco; Pedreschi, Romina
This research aimed to evaluate atmospheric pressure immersion (API) and vacuum impregnation (VI) of non -hydrolyzed and hydrolyzed tara gallotannins (TE and THE) extracts and the purification process by leaching with ethyl acetate (TE-L and THE-L) and absorption chromatography on the acrylamide (AA) mitigation in potato chips. Better results were obtained with THE-L at hydrolysis degrees of 48.5 and 99.8 % and API with AA reduction of 57.9 and 61.7 %, respectively (p > 0.05), while with TE-L, AA reduction was 29.2 %. Instead, THE-L and TE-L with VI reduced AA by 70.3 and 66.4 %, respectively. In potato chips subjected to THE-L treatment, phenolic compounds and ABTS AC increased in 86.5-91.0 % and 71.0-103.2 %, respectively compared to the control. The main antioxidants were identified in the extracts and in potato chips. Tara gallotannins are an interesting alternative to mitigate AA formation and to enhance the antioxidant power of potato chips.
Automated Design of a Computer Vision System for Visual Food Quality Evaluation
(2013) Mery Quiroz, Domingo Arturo; Pedreschi, Franco; Soto, Alvaro
Characterizing the Variability of Enzymatic Browning in Fresh-Cut Apple Slices
(2014) Quevedo, Roberto; Valencia, Emir; Lopez, Patricia; Gunckel, Erna; Pedreschi, Franco; Bastias, Jos
Browning reaction variability in apple slices was characterized using a new procedure denominating the differential pixel method. Using this method, a kinetic rate and an empirical order of reaction were derived for each pixel in an image corresponding to a sliced apple surface undergoing browning; each pixel in the image can be seen as a small portion of the fruit. In the experiments, 40 samples of fresh-cut apple slice were put on a computer vision system and images recorded over time at a room temperature of 5 A degrees C. Data was fitted to the Weibullian model kinetic. Results confirmed strong heterogeneity in the values of enzymatic browning kinetic rate on the apple surface; this variability was characterized as a normal logarithmical distribution, with a mean rate kinetic value of the -0.0117 A +/- 0.0036 units of L* decayed per minute. The empirical order of reaction was distributed on the surface following a normal statistical distribution with a mean equal to 0.451 A +/- 0.046. No statistical differences were established in the kinetic rate and in the empirical order when the differential pixel method was compared with the traditional method (where a mean of the L* intensity value was used).
Color development and acrylamide content of pre-dried potato chips
(ELSEVIER SCI LTD, 2007) Pedreschi, Franco; Leon, Jorge; Mery, Domingo; Moyano, Pedro; Pedreschi, Romina; Kaack, Karl; Granby, Kit
The objective of this work was to study the development of color formation in pre-dried potato slices during frying and acrylamide formation in the final potato chips. Color measurement was done by using an inexpensive computer vision technique which allowed quantifying representatively and precisely the color of complex surfaces such as those of potato chips in L*a*b* units from RGB images. Prior to frying, potato slices (Desiree variety, diameter: 37 mm, width: 2.2 mm) were blanched in hot water at 85 degrees C for 3.5 min. Unblanched slices were considered as the control. Slices of the same dimensions were blanched as in the previous step, and then air-dried until reaching a moisture content of 60% (wet basis). These samples were called pre-dried potato slices. Potato slices were fried at 120 degrees C, 140 degrees C, 160 degrees C and 180 degrees C until reaching moisture contents of similar to 1.8% (total basis) for color quantification. Acrylamide concentration was determined only in final chips fried at 120 degrees C, 150 degrees C and 180 degrees C and compared with that of two brands of commercial chips produced in Chile (Moms and Frito Lay). Color values in L*a*b* units were recorded at different sampling times during frying at the four mentioned temperatures using the total color difference parameter (Delta E). Pre-drying did not affect the color of potato chips considerably when compared against blanched chips; however when fried at 180 degrees C, pre-dried potato chips present 44%, 22%, 44% lower acrylamide content than that of the control, Moms and Frito Lay chips, respectively. (c) 2006 Elsevier Ltd. All rights reserved.
Color kinetics and acrylamide formation in NaCl soaked potato chips
(ELSEVIER SCI LTD, 2007) Pedreschi, Franco; Bustos, Oscar; Mery, Domingo; Moyano, Pedro; Kaack, Karl; Granby, Kit
The objective of this work was to study the kinetics of color development in blanched and blanched-NaCl impregnated potato slices during frying by using the dynamic method and also to evaluate the effect of NaCl in reducing acrylamide formation in potato chips. The measurement of color was done by using an inexpensive computer vision technique which allowed quantifying in a more precise and representative way the color in L*a*b* units of complex surfaces such as those of potato slices during frying. The effect of potato slice soaking in NaCl was evaluated not only for color change but also for acrylamide formation. Prior to frying, potato slices (Desiree variety, diameter: 37 mm, width: 2.2 min) were blanched in hot water at 85 degrees C for 3.5 min; these slices were considered as the control. Slices of the same dimensions were blanched as in the previous step, and soaked at 25 degrees C in a NaCl solution of 0.02 g/l 5 min at 200 rpm of agitation. These samples were considered as NaCl soaked potato chips.
Color measurement in L*a*b* units from RGB digital images
(ELSEVIER, 2006) Leon, Katherine; Mery, Domingo; Pedreschi, Franco; Leon, Jorge
The superficial appearance and color of food are the first parameters of quality evaluated by consumers, and are thus critical factors for acceptance of the food item by the consumer. Although there are different color spaces, the most used of these in the measuring of color in food is the L*a*b* color space due to the uniform distribution of colors, and because it is very close to human perception of color. In order to carry out a digital image analysis in food, it is necessary to know the color measure of each pixel on the surface of the food item. However, there are at present no commercial L*17*b* color measures in pixels available because the existing commercial colorimeters generally measure small, non-representative areas of a few square centimeters. Given that RGB digital cameras obtain information in pixels, this article presents a computational solution that allows the obtaining of digital images in L*a*b* color units for each pixel of the digital RGB image. This investigation presents five models for the RGB -> L*a*b* conversion and these are: linear, quadratic, gamma, direct, and neural network. Additionally, a method is suggested for estimating the parameters of the models based on a minimization of the mean absolute error between the color measurements obtained by the models, and by a commercial colorimeter for uniform and homogenous surfaces. In the evaluation of the performance of the models, the neural network model stands out with an error of only 0.93%. On the basis of the construction of these models, it is possible to find a L*a*b* color measuring system that is appropriate for an accurate, exacting and detailed characterization of a food item, thus improving quality control and providing a highly useful tool for the food industry based on a color digital camera. (c) 2006 Elsevier Ltd. All rights reserved.
Description of the kinetic enzymatic browning in banana (Musa cavendish) slices using non-uniform color information from digital images
(ELSEVIER, 2009) Quevedo, Roberto; Diaz, Oscar; Ronceros, Betty; Pedreschi, Franco; Miguel Aguilera, Jose
A novel methodology "fractal browning indicator" (FBI) is presented, that describes the enzymatic browning kinetic based on the use of irregular color patterns from banana slice images. It uses the fractal Fourier texture image value in a selected area, to calculate a fractal dimension (FD), which represents the complexity of color distribution. During the procedure, colors from digital images were first transformed to L*a*b* space color using a transformation function (quadratic model), in order to derivate three color channels, lightness (L*), redness (a*), and yellowness (b*). In the results, lightness and yellowness parameters decreased during the browning kinetic, when their respective FD values increased, indicating major color distribution complexity in a selected area analyzed during the kinetic. The redness color (a*) did not show any statistical variation. The empirical power law model was suitable to correlate enzymatic browning kinetic data both for FBI and for the traditional method (when an L* mean was used). However, enzymatic browning rates using the FBI method, were between 8.5 and 35 times higher than rates calculated with the traditional method. (C) 2009 Elsevier Ltd. All rights reserved.
Development of a computer vision system to measure the color of potato chips
(ELSEVIER, 2006) Pedreschi, Franco; Leon, Jorge; Mery, Domingo; Moyano, Pedro
The objective of this research was to design and implement an inexpensive computer vision system for measuring the color of a highly heterogeneous food material not only in shape as well in color such as potato chips in L*a*b* units from RGB images. The system was composed of (i) a digital color camera for acquiring the images in a digital format, (ii) a computer for storage the images, (c) image analysis routines integrated into a software programmed in Matlab that converts the color RGB of the food image into L*a*b* units. In this way the color of potato chips can be calculated in L*a*b* units over representative areas and in a reproducible way. The kinetics of color changes in potato slices during frying at four temperatures was followed using the implemented computer vision system (CVS). Color values in L*a*b* units were recorded at different sampling times during frying at the four oil temperatures using the total color change parameter (AE). Chips fried at higher temperatures get darker as expected and showed by the CVS. The implemented computer vision system can be used to study as well foods different from potato chips by selecting their proper settings for image acquisition and digital image processing. (c) 2006 Elsevier Ltd. All rights reserved.
Frying of Potatoes: Physical, Chemical, and Microstructural Changes
(TAYLOR & FRANCIS INC, 2012) Pedreschi, Franco
Frying is one of the oldest unit operations and is used not only in industry but also at home. The most commonly fried vegetable is potato, for important commercial products such as potato chips, par-fried potatoes, and french fries. Quality parameters of interest for fried potatoes include physical and chemical properties such as color, mechanical properties (e. g., crispness, hardness, etc.), structural properties (e. g., porosity and roughness), oil content, and water content, among others. Some chemical contaminants such as acrylamide and furan are heat-generated during the frying of potato slices or strips, leading to final fried pieces with considerable amounts of these contaminants. The controllable variables in industrial frying processes are generally potato variety, oil type, frying time, and frying temperature. Therefore, the study of the quality changes during frying is critical because knowledge regarding kinetics parameters will enable prediction of the final quality in fried potatoes and improvements in the final product value by selecting properly the processing conditions. Finally, modern techniques such as computer vision provide valuable tools to quantify and predict physical and chemical properties of potato pieces during frying in a fast and noninvasive way. In addition, computer vision can allow us to classify fried potatoes in different quality classes previously determined by sensorial panels.
Furan Occurrence in Starchy Food Model Systems Processed at High Temperatures: Effect of Ascorbic Acid and Heating Conditions
(AMER CHEMICAL SOC, 2012) Mariotti, Maria; Granby, Kit; Fromberg, Arvid; Risum, Jorgen; Agosin, Eduardo; Pedreschi, Franco
Furan, a potential carcinogen, has been detected in highly consumed starchy foods, such as bread and snacks; however, research on furan generation in these food matrixes has not been undertaken, thus far. The present study explored the effect of ascorbic acid addition and cooking methods (frying and baking) over furan occurrence and its relation with the non-enzymatic browning in a wheat flour starchy food model system. Results showed that furan generation significantly increased in the presence of ascorbic acid after 7 mm of heating (p < 0.05). The strongest effect was observed for baked products. Additionally, the furan content in fried products increased with the increase of the oil uptake levels. As for Mallard reactions, in general, the furan level in all samples linearly correlated with their degree of non-enzymatic browning, represented by L* and a* color parameters (e.g., wheat flour baked samples showed a R-2 of 0.88 and 0.87 for L* and a*, respectively), when the sample moisture content decreased during heating.
Grading of Potatoes
(2008) Pedreschi, Franco; Mery Quiroz, Domingo Arturo; Marique, Thierry
Inhibition of the formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 2-amino-3,8-dimethyl-3H-imidazo[4,5-f]quinoxaline (MeIQx) by phenolics in model systems and beef patties
(2025) Caro Cabarcas, Angey D.; Alcon, Esmeralda; Mariotti-Cellis, María Salomé; Pedreschi, Franco; Hidalgo, Francisco J.; Zamora, Rosario
The comparative inhibition of the formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 2-amino-3,8-dimethyl-3H-imidazo[4,5-f]quinoxaline (MeIQx) by phenolics in both model systems and beef patties was studied to better understand the protective role of these compounds. Model systems were selected to produce PhIP and MeIQx by carbonyl-amine reactions. Obtained results showed that their formation was inhibited up to 100 % by assayed phenolics. Among simple phenolics, m-diphenols were usually more effective than o-diphenols, and MeIQx was better inhibited than PhIP because m-diphenols both produce the Strecker degradation of amino acids to a lower extent than o-diphenols, and trap acrolein (responsible for MeIQx formation) better than phenylacetaldehyde (responsible for PhIP formation). When complex phenolics were assayed, other groups also contributed to the observed protective function. However, relative inhibitions of both compounds in model systems and beef patties were correlated, therefore suggesting that the formation of PhIP and MeIQx also occurs in beef patties by carbonyl-amine reactions.
Integrated effect of yeast inoculation and roasting process conditions on the neo formed contaminants and bioactive compounds of Colombian roasted coffee (Coffea arabica)
(2023) -Rodriguez, Yeison Fernando Barrios; Gutierrez-Guzman, Nelson; Amorocho-Cruz, Claudia Milena; Pedreschi, Franco; Celis, Maria Salome Mariotti
The rational design of methodologies to control the neoformed compounds occurrence (NFCs), such as acryl-amide and hydroxymethylfurfural (HMF) in roasted coffee, must consider the preservation of the bioactive compounds contained in this beverage. The aim of this work was to evaluate the integrated effect of yeast inoculation during the fermentation stage and the modification of roasting parameters on the final concentra-tions of NFCs and bioactive compounds of roasted coffee. A completely randomized factorial design was used to evaluate the effect of yeast inoculation (with and without inoculation), roasting temperature (150, 180 and 210 degrees C) and roast degree (medium, dark) on the (i) physicochemical characteristics (volume change, mass loss, water activity, non-enzymatic browning index, antioxidant capacity, total polyphenols, chlorogenic acid and caffeine) as well as HMF and acrylamide levels of roasted coffee. Response variables were analyzed separately by ANOVA and clustering of treatments was explored by PCA. Yeast inoculation did not significantly (p > 0.05) affect volume change, mass loss, antioxidant capacity, total polyphenols content, and caffeine contents. The interaction of evaluated factors significantly decreased (p < 0.05) the acrylamide and HMF contents of roasted coffee (43 % and 56.0 %, respectively). Based on PCA grouping the best treatments were medium roast at 210 degrees C (inoculated and uninoculated) and at 180 degrees C (inoculated). Under these conditions it is possible to produce a roasted coffee mitigated in neo formed contaminants that present the physicochemical properties of original product.
Irradiation kills microbes: can it do anything harmful to the food?
(Academic Press, 2020) Pedreschi, Franco; Mariotti Celis, María Salomé
Food irradiation is an efficient technology that can be used to ensure food safety by eliminating insects and pathogens to prolong the shelf life, among others. In most of the cases, the process could be applied to fresh or frozen products without affecting the nutritional value and sensory quality of treated foods. The scientific records about food irradiation confirm with a high degree of assurance that foods and food ingredients treated using this method are safe and fit for human consumption. Besides, irradiation can induce certain alterations that can modify both the chemical composition and the nutritional value of foods. These changes depend on the food composition, the irradiation dose, and factors such as temperature and presence or absence of oxygen in the irradiating environment. Currently, food irradiation is approved in more than 60 countries, and there has been a notable growth in production and trade of irradiated foods since 2010.
Is the dietary acrylamide exposure in Chile a public health problem?
(2021) Barrios-Rodriguez, Yeison Fernando; Pedreschi, Franco; Rosowski, Jaime; Gomez, Juan Pablo; Figari, Nicole; Castillo, Oscar; Mariotti Celis, Maria Salome
This study estimates for the first time dietary acrylamide intake in Chile and conducts exposure risk assessments using the margin of exposure (MOE) method. A consumption frequency survey of starchy foods was carried out in the metropolitan region of Santiago, Chile on people from different socioeconomic levels aged between 12 and 65 years old. The acrylamide contents of the most frequently consumed foods were determined by an in-house validated GC-MS technique. The potatoes and bread group contributed similar to 77% to the dietary acrylamide exposure in Chile, with estimated daily mean exposure of 0.55 mu g kg(bw)(-1) day(-1) and 0.22 mu g kg(bw)(-1) day-1, respectively. Chilean population aged between 12 and 17 years old presented the highest acrylamide intake (mean, 1.27 mu g kg(bw)(-1) day(-1); 95th percentile, 3.90 mu g kg(bw)(-1) day(-1)). Finally, since the estimated MOEs were lower than 10,000, the dietary acrylamide exposure in the metropolitan region of Santiago, Chile is of public health concern according to the EFSA criteria.
Prediction of Mechanical Properties of Corn and Tortilla Chips by Using Computer Vision
(2012) Matiacevich, Silvia B.; Mery Quiroz, Domingo Arturo; Pedreschi, Franco
Production of contaminants during thermal processing in both industrial and home preparation of foods
(Elsevier, 2022) Pedreschi, Franco; Mariotti Cellis, María Salomé
The problem of processing contaminants is now one of the most challenging issues the food industry needs to address. Heat processing contaminants may be defined as substances that are produced in a food when it is cooked or processed, and they are not present or present at much lower concentrations in the raw, unprocessed food. These heat toxic compounds and undesirable either because they have an adverse effect on product quality or because they are potentially harmful. It is important to highlight that Maillard Reaction (Mr) is the most important chemical reaction occurring during food processing at high temperature unit operations since it is crucial for the development of attractive sensory food attributes of the final products, improving their digestibility, ensuring microbial safety, and developing flavor and taste to name just three. On the other hand, Mr has shown that heating of starchy and protein food matrixes can generate various kinds of potentially toxic compounds (PTCs). Consequently, PTCs could be mitigated by favoring the processing conditions under which Mr is inhibited and/or reducing the PTC crucial precursors in raw food materials before being heated at high temperature unit operations such as frying, extrusion, roasting, grilling, baking, and among others. Mr also plays a crucial role in the heat formation of some PCTs such as acrylamide (AA), furan, 5-hydroxymethylfurfural (HMF), and heterocyclic amines (HAs) either in starchy and/or protein food matrixes processed by excessive heating. In this chapter, we will present some of the most important PTCs in foods such as AA, furan, HMF, and HAs. We will show you some mitigation strategies for PTCs considering the following issues: (1) raw materials and precursor contents specific for the formation of one or more PCTs, (2) heating processing conditions, and (3) mecanism(s) of PTC formation under specific conditions. This information will help you to generate foods heated at high processing temperatures while minimizing PCT formation and preserving the quality attributes of the desired food product. In this way, we will contribute in reducing the exposure of consumers to dietary PCTs.
Quantification of enzymatic browning in apple slices applying the fractal texture Fourier image
(ELSEVIER SCI LTD, 2009) Quevedo, Roberto; Jaramillo, Marcela; Diaz, Oscar; Pedreschi, Franco; Miguel Aguilera, Jose
A new approach (FBI) describing the enzymatic browning kinetics for three apple cultivars, is presented. It is based on quantification of the irregular color patterns that emerge from the apple surface during enzymatic browning, rather than using the color average in the same area analyzed. In the experiments, three apple cultivars slices were placed under a computer vision system and color digital images were captured. The images were transformed to Lab space color using a quadratic transformation function and the Fourier fractal texture image was used to calculate a fractal dimension value (FD), in order to represent the complexity of lightness intensity distribution (L) over the surface. FD (proposed method) and the mean L value (traditional method) were used indistinctly (as a fractional conversion) to model the enzymatic kinetic using the power-law model. The results showed that the fractal theory can be used to describe the browning kinetic and to distinguish apple cultivars, based on their browning sensitivity under the same experimental conditions. Enzymatic browning rates derived using the fractal kinetic method, were between 14.3 and 23.2 times (in absolute value) higher than the rates calculated with the traditional method. The fractional first-order model was established only for kinetics calculated using the traditional method. (c) 2009 Elsevier Ltd. All rights reserved.

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