Application of Phenolic Compounds for Food Preservation: Food Additive and Active Packaging

Phenolic compounds are well known for their health benefits related to antioxidant activity. In addition, this kind of compounds can be extracted from natural sources, such as olives, grapes, fruits, vegetables, rice, spices, herbs, tea and algae, among others. In this way, these compounds have increased their popularity and, little by little, the consumers are more interested in these compounds due to the fact that they come from natural sources and because they have health biological activity. In fact, other important characteristics associated to phenolic compounds are the antimicrobial activity, because phenolics have the capacity of retarding the microbial invasion in some products and avoiding the putrefaction of others, mainly fruits and vegetables. These properties allow phenolic compounds to be suitable for numerous food preservation applications. Therefore, different kinds of products can be fortificated with phenolic compounds to extend the shelf life of some foods, to turn them in functional food or to incorporate them in food packaging. Active packing is an innovative strategy where phenolic compounds can play an important role for improving the global assessment and extend the shelf life of commercial products

Impact of thermal sterilization on the physicochemical-sensory characteristics of Californian-style black olives and its assessment using an electronic tongue

The effect of thermal sterilization processes on the physicochemical parameters and sensory characteristics of Californian-style black olives, from Hojiblanca and Manzanilla Cacereña brine solutions, were evaluated. Two-way ANOVA showed that Hojiblanca olives had a lower phenols content and defect intensity and that increasing the sterilization period resulted in a decrease in total phenols and an increase of the cooked defect. The impact of thermal sterilization was further evaluated using a potentiometric electronic tongue, which was capable of discriminating the different sterilization treatments (repeated K-fold cross-validation sensitivity: 89.0?±?15.0% to 97.0?±?6.0%). Moreover, multiple regressions allowed the prediction of phenols (R2???0.95?±?0.03) and the intensity of the defect (R2???0.95?±?0.04). These results point out the feasibility of the electronic tongue as an analytical tool for monitoring the effects of thermal sterilization treatments. Furthermore, the satisfactory results obtained for the brine solutions may foresee a practical non-destructive method for indirect quality assessment of table olives.Consejería de Educación y Empleo of the Junta de Extremadura to work with a scholarship at the Polytechnic Institute of Bragança for 4 months (Resolución de 18 de julio de 2019, DOE de 25 de julio de 2019, no 143) (Expedient number A28). Nuno Rodrigues thanks to National funding by FCT- Foundation for Science and Technology, P.I., through the institutional scientific employment program-contract. The authors are also grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER, under Programme PT2020, for the financial support of CIMO (UID/AGR/00690/2019) and of CEB (UID/BIO/04469/2019) and to BioTecNorte operation (NORTE-01-0145-FEDER-000004)info:eu-repo/semantics/publishedVersio

Assessing acrylamide content in sterilized Californian-style black table olives using HPLC-MS-QQQ and a potentiometric electronic tongue

The study aimed to evaluate the effects of olive cultivar (cvs. Manzanilla Cacereña and Hojiblanca) and the sterilization intensity/time-period (F0 of 1025minat 121±3°C) on the formation of acrylamide in table olives and brine. Olive cultivar and thermal sterilization had a significant impact on the amount of acrylamide produced (varying from 228±94 to 286±110 and 336±126 to 373±159ngg1, for table olives and brine, respectively, determined by HPLC-MS-QQQ). Moreover, for both cultivars, linear positive relationships (0.931R20.994) were found between the acrylamide concentration in olives and respective brine solutions, allowing to foresee a non-destructive indirect methodology for quantifying acrylamide in table olives. Finally, a potentiometric E-tongue was used to quantify acrylamide in both matrices. The lipid sensor membranes comprised on the sensor device showed potentiometric semi-logarithmic responses (0.962R20.999) towards the acrylamide concentration for aqueous standard solutions, permitting the establishment of accurate multiple linear predictive models for the quantification of acrylamide in olives and brine solutions (repeated K-fold-CV: 0.97±0.03R20.99±0.01; 12±8RMSE 28±14ngg1) for both olive cultivars. E-tongue could be used as non-destructive indirect detection method of acrylamide, based on the brine solution evaluation, and so, a complementary analytical tool to the conventional chromatographic analysis.Daniel Martín-Vertedor thanks the mobility grant of the Consejeríade Educación y Empleo of the Junta de Extremadura to work with ascholarship at the Polytechnic Institute of Bragança for 4 months(Resolución de 18 de julio de 2019, DOE de 25 de julio de 2019, no143) (Expedient number A28). The authors are grateful to theFoundation for Science and Technology (FCT, Portugal) and FEDERunder Program PT2020 forfinancial support to CIMO (UIDB/00690/2020) and to CEB (UIDB/04469/2020) units and to BioTecNorte op-eration (NORTE-01-0145-FEDER-000004) funded by the EuropeanRegional Development Fund under the scope of Norte2020 - ProgramaOperacional Regional do Norte. Nuno Rodrigues thanks to Nationalfunding by FCT- Foundation for Science and Technology, P.I., throughthe institutional scientific employment program-contract. The authorswish to thank to the Elemental and Molecular Analysis Service be-longing to the Research Support Service of the University ofExtremadura by the development of acrylamide determination methodand MaDolores López Soto and Elena Rodríguez Paniagua for their helpin the performance of this study.info:eu-repo/semantics/publishedVersio

Calcium applications throughout fruit development enhance olive quality, oil yield, and antioxidant compounds' content

BACKGROUND: Calcium is a preservative andfirming agent largely used in the table olive industry. Foliar applications of cal-cium (as calcium chloride, CaCl2) before harvest have been proposed in other fruits to increasefirmness and reduce physiolog-ical disorders or internal damage. However, there is still a shortage of information regarding the source, the concentration, thenumber, and the period of calcium application onto the canopy to get an effective response of olive quality. In this study, weaimed to investigate the effect of two concentrations of CaCl2foliar treatments (0.5% and 1.0%), applied at different stagesof fruit development (at the end of fruit set, end of pit hardening, and prior to harvesting), on olive quality for two varieties(‘Manzanilla de Sevilla’and‘Ascolanta tenera’), cultivated in two different geographical areas (Spain and Italy respectively).RESULTS: The calcium concentrations applied enhanced the fruit calcium content and decreased sodium and potassium. Theyalso improved the mechanical properties without modifying fruit morphology or cuticle thickness; nor did they cause phytotox-icity. Foliar treatments increased the oil content in the pulp (dry weight basis) and the amount of hydroxytyrosol, tyrosol, andoleuropein, among other phenols

Fluorescence Monitoring Oxidation of Extra Virgin Olive Oil Packed in Different Containers

‘Picual’ olive oil was stored in different types of containers for 10 months and monitored via quality parameters. In combination with the mentioned analysis, non-destructive fluorescence spectroscopy was performed combined with multivariate analysis to monitor and quantify oil quality levels. Excitation emission matrices (EMMs) were analyzed using parallel factor analysis (PARAFAC). According to the quality parameters, it was observed that Transparent Crystal (TC) and Opaque Crystal (OC) samples were the ones that deteriorated faster due to their higher exposure to light in comparison with Plastic (P) and Canned (C) samples. In a fast and non-destructive manner, the fluorescence spectroscopy-based prototype successfully monitored the oxidation changes in the EVOOs. Unfolded partial least squares (U-PLS) was used to generate a regression model to quantify quality parameters. Good correlation coefficients were found for the peroxide index, K232 and the oxidative stability index (r2 between 0.90 and 0.94 for cross-validation and validation). For all of that, the results obtained confirmed the ability of fluorescence spectroscopy to monitor the quality of olive oil and EEMs combined with U-PLS can be used to analyze these parameters, eluding the classical methods

Bioavailability of Phenolic Compounds in Californian-Style Table Olives with Tunisian Aqueous Olive Leaf Extracts

Recent advances in biotechnology have ensured that one of the main olive tree by-products is olive leaf extract (OLE), a rich source in bioactive compounds. The aim of this work was to study the phenolic composition in different OLEs of three Tunisian varieties, namely, ‘Sayali’, ‘Tkobri’, and ‘Neb Jmel’. The in vitro biodigestibility effect after ‘Sayali’ OLE addition to Californian-style ‘Hojiblanca’ table olives was also studied. This OLE contained bioactive molecules such as hydroxytyrosol, tyrosol, oleropeine, Procianidine B1 (PB1), and p-cumaric acid. These compounds were also found in fresh olives after OLE was added. Furthermore, from fresh extract to oral digestion, the detected amount of bioavailable phenol was higher; however, its content decreased according to each phase of gastric and intestinal digestion. In the final digestion phase, the number of phenols found was lower than that of fresh olives. In addition, the phenolic content of Californian-style ‘Hojiblanca’ table olives decreased during the in vitro digestion process. The antioxidant activity of this variety decreased by 64% and 88% after gastrointestinal digestion, being the highest antioxidant capacity found in both simulated gastric and intestinal fluid, respectively. The results show us that the ‘Sayali’ variety is rich in phenolic compounds that are bioavailable after digestion, which could be used at an industrial level due to the related health benefits

Identification of mitigation strategies to reduce acrylamide levels during the production of black olives

Californian-style processes are widely applied to the elaboration of black ripe olives in the table olive industry. During this procedure, a carcinogenic contaminant known as acrylamide is generated in thermal oxidation. The content of this compound can be modified according to the stage of processing. The present study evaluates the conditions pertaining to different phases of the elaboration process with the aim of identifying optimal conditions for the production of table olives with the lowest acrylamide concentration possible. ‘Hojiblanca’ variety olives were used. Olives were harvested at two different maturation stages, specifically, the green and yellow-green stages. Olives with yellow-green maturation indices had higher acrylamide concentrations than green table olives. Significant reductions in the contaminant were observed as storage time increased, with green olives stored for 21 months displaying the lowest acrylamide levels. Acrylamide was also decreased by spraying olives with water (18 % reduction) and washing them with water heated to 25 °C for 40 min (36 % reduction). Following treatment with lye during the packaging and preparation of olives, unpitted olives contained 12–31% more acrylamide than pitted olives and 42–62% more than sliced olives. Outcomes were the same for olives canned both with and without brine. The presence of CaCl2 and the addition of greater NaCl concentrations (from 2% to 4% w/v), increased the acrylamide content in all olive formats. This increase was not observed in olives not stored in liquid. Outcomes reported here are valuable for redesigning the elaboration process of industrial black ripe olives and allowing producers to manufacture better-quality products with significantly reduced acrylamide concentrations.The research leading to this paper received financial support from Junta de Extremadura (project IB18125) which is co-funded by the European Regional Development Fund. Furthermore, this work has also been supported by research groups belonging to Junta de Extremadura (GR18162).Peer reviewe

Application of Digital Olfaction for Table Olive Industry

The International Olive Council (IOC) established that olives must be free of odors, off-flavors, and absent of abnormal ongoing alterations or fermentations. The use of electronic devices could help when classifying defects in a fast, non-destructive, cheap, and environmentally friendly way. For all of that, table olives were evaluated according to IOC regulation in order to classify the defect predominant perceiving (DPP) of the table olives and their intensity. Abnormal fermentation defects of Spanish-style table olives were assessed previously by an IOC-validated tasting panel. ‘Zapateria’, ‘Putrid’, and ‘Butyric’ were the defects found at different concentrations. Different volatile compounds were identified by gas chromatography in altered table olives. The same samples were measured with an electronic nose device (E-nose). E-nose data combined with chemometrics algorithms, such as PCA and PLS-DA, were able to successfully discriminate between healthy and non-healthy table olives, being this last one also separated between the first and second categories. Volatile compounds obtained with gas chromatography could be related to the E-nose measuring and sensory analysis, being capable of matching the different defects with their correspondents’ volatile compounds

Industrial strategies to reduce acrylamide formation in Californian-style green ripe olives

This article belongs to the Special Issue New Frontiers in Acrylamide Study in Foods: Formation, Analysis and Exposure Assessment.Acrylamide, a compound identified as a probable carcinogen, is generated during the sterilization phase employed during the processing of Californian-style green ripe olives. It is possible to reduce the content of this toxic compound by applying different strategies during the processing of green ripe olives. The influence of different processing conditions on acrylamide content was studied in three olives varieties (“Manzanilla de Sevilla”, “Hojiblanca”, and “Manzanilla Cacereña”). Olives harvested during the yellow–green stage presented higher acrylamide concentrations than green olives. A significant reduction in acrylamide content was observed when olives were washed with water at 25 °C for 45 min (25% reduction) and for 2 h (45% reduction) prior to lye treatment. Stone olives had 21–26% higher acrylamide levels than pitted olives and 42–50% higher levels than sliced olives in the three studied varieties. When calcium chloride (CaCl2) was added to the brine and brine sodium chloride (NaCl) increased from 2% to 4%, olives presented higher concentrations of this contaminant. The addition of additives did not affect acrylamide levels when olives were canned without brine. Results from this study are very useful for the table olive industry to identify critical points in the production of Californian-style green ripe olives, thus, helping to control acrylamide formation in this foodstuff.The research leading to these results received financial support from Junta de Extremadura (project IB18125) cofinanced by the European Regional Development Fund. Furthermore, this work has been also supported by research groups of Junta de Extremadura (GR18162).Peer reviewe

E-Nose Quality Evaluation of Extra Virgin Olive Oil Stored in Different Containers

The degradation process of virgin olive oil (VOO) is related to storage time and the type of storage container used. The aim of this work is to explore the evolution of the VOO quality stored in different container types over a defined storage period in order to predict the organoleptic characteristics using a non-destructive technique such as the electronic-nose (E-nose). The “Picual” variety VOO was stored in different containers over a period of 21 months and monitored using sensory analysis, volatile compounds, and an E-nose. The panelists showed that oil stored in dark glass bottles and in green polyethylene bottles began to show defects after 12 and 15 weeks, respectively. However, oil stored in tin containers retained its quality throughout the 21 months studied. A total of 31 volatile compounds were identified, and the evolution of the volatile profile in the different containers during the storage period was studied. The E-nose data were able to classify oil quality by container using principal component analysis (PCA). Furthermore, the E-nose data combined with partial least squares (PLS) regression enabled the building of a predictive model to quantify sensory defect values (RCV2 = 0.92; RCV2 = 0.86), evidencing that this technique would be an appropriate screening tool to support a sensory panel