Polyphenol-Enriched Pectin from Pomegranate Peel: Multi-Objective Optimization of the Eco-Friendly Extraction Process.

A multi-objective optimization was performed using response surface methodology to obtain a high-value-added product, pectin enriched in polyphenols, from pomegranate peel. For this purpose, a green extraction technique that combines citric acid and ultrasound was carried out considering three variables: time, pH, and temperature. The extraction procedure was optimized using the Box-Behnken design, these being the most suitable conditions, with an extraction time of 34.16 min, a pH of 2.2, and a temperature of 89.87 °C. At this point, the pectin yield was 31.89%, with a total retained polyphenol content of 15.84 mg GAE/g pectin. In addition, the water activity, ash content, equivalent weight, methoxyl content, and degree of esterification were determined for the pectin obtained at the optimal point. This study demonstrates that polyphenol-enriched pectin can be obtained from pomegranate peel via an eco-friendly and efficient method, and that it presents similar properties to commercial pectin, preserving its quality and with potential use as an ingredient or food supplement with a high nutritional value. This work contributes to developing sustainable strategies to valorize pomegranate agro-industrial waste and produce high-value functional ingredients.

Effect of geographical location, processing and simulated digestion on antioxidant characteristics of quince (Cydonia oblonga).

Quince fruit (Cydonia oblonga Miller) is an important source of bioactive compounds, especially of phenolic compounds, that's why it is considered a good source of antioxidants. However, it is known that the antioxidant characteristics and the beneficial effect of foods are affected by the variety, geographical origin, processing and gastrointestinal digestion. In this work, the effects of the geographical origin, processing, and simulated digestion of quince jam on its antioxidant characteristics were studied. Phenolic composition and antioxidant capacity were determined in quince fruit and jam from four different locations in San Juan, Argentina. The results showed that quince fruit samples from St. Lucia had the highest total phenolic content (5.13 mg GAE/g; p < 0.05) and in vitro antioxidant capacity measured by ferric-reducing antioxidant power assay (FRAP) and radical-scavenging capacity assay (DPPH· and ABTS·+ ). With regard to quince jam, a positive effect was observed on its antioxidant characteristics after processing. Twenty-one phenolics were detected in jam, being most of them derivatives of hydroxycinnamic acids (eg. 5-caffeoylquinic acid; 4-caffeoylquinic acid and quinic acid). Studies on stability and bioaccessibility of quince phenolics showed that less than 25% of the initial phenolics in jam were detected after digestion being quinic acid and hydroxycinnamic acids the most resistant. The in vitro antioxidant capacity showed, in general, a similar trend to the phenolics content throughout the digestion process. The results obtained showed that the antioxidant activity of quince and jam is related to the type and amount of phenolics in the samples, which depends on the geographical origin, processing, and gastrointestinal digestion. These variables are not always taken into account when studying the probable antioxidant activity of food, even though they should be considered for a complete nutritional evaluation of a food.

Drying and rehydration kinetics of peeled and unpeeled green apple slices (Granny Smith cv).

In this work, the kinetics of drying and rehydration of green apple slices peeled and unpeeled (Granny Smith cv) were studied. The apple slices were dried at 50, 60, and 70 °C, and after that, rehydrated at ambient (Ta) and boiling temperature (Tb). The drying kinetics were adjusted with the Dincer and Dost model, giving a good fit. Effective diffusivity (Deff) and the convective mass transfer coefficient (hm) were also determined, both coefficients increase with drying temperature, being 1.25 × 10-9 m2 s-1 and 9.53 × 10-7 m2 s-1 the highest values obtained for the peeled apple slices respectively. Peleg and Weibull models were adjusted to the rehydration experimental data obtaining a good fit (R2 > 0.99). Deff values increase significantly with rehydration temperature but take similar values between peeled and unpeeled samples. Acidity, pH, moisture content, solid soluble content, and equivalent diameter were determined to compare the fresh apple slices with those after dehydration and the post-rehydration process. The apple slices rehydrated at boiling temperature better preserved the characteristics of fresh samples due to the short immersion times in water, no significant differences were observed between peeled and unpeeled apples. According to the results, it is convenient to dry the apple slices unpeeled at 70 °C and rehydrate them at Tb.

Effects of the amendment with almond shell, bio-waste and almond shell-based biochar on the quality of saline-alkali soils.

This study aimed to evaluate the effect of the amendment with almond shell bio-waste (AS) and almond shell-based biochar (ASB), in different mass ratios (5, 10, and 15%), on the physicochemical properties of three different saline soils, using the growth of arugula seedlings as a bioindicator of the enhancement achieved. Data were analyzed based on a completely randomized design in a factorial arrangement with four replications. The results showed that the low-salinity soil (T1) presented the best physicochemical characteristics and growth parameters. The addition of AS and ASB in low proportions to the saline soils reduced the pH and electrical conductivity values. An increase in the amendment proportion led to an increase in these variables. Moisture, organic matter, and organic carbon increased, and the cation exchange capacity decreased, generating positive effects on soil quality. The values of exchangeable sodium percentage (ESP) showed that T3 presented the highest sodicity, followed by T2 and T1. The treatment with 5% ASB produced better results regarding total plant length, fresh and dry weights, leaf area, and leaf chlorophyll content. Finally, linear regression models were applied to describe the dependence of the agronomic variables on the ratio of biochar added.

Producing non-traditional flour from watermelon rind pomace: Artificial neural network (ANN) modeling of the drying process.

An artificial neural network (ANN) model was developed to simulate the convective drying process of watermelon rind pomace used in the fabrication of non-traditional flour. Also, the drying curves obtained experimentally were fitted with eleven different empirical models to compare both modeling approaches. Lastly, to reduce the required fossil fuel in the convective drying process, two types of solar air heaters (SAH) were presented and experimentally evaluated. The optimization of the ANN by a genetic algorithm (GA) resulted in an optimal number of neurons of nine (9) for the first hidden layer and ten (10) for the second hidden layer. Also, the ANN performed better than the best fitted empirical model. Simulations with the trained ANN showed very promising generalization capabilities. The type II SAH showed the best performance and the highest air temperature it reached was 45 °C. The specific energy consumption (SEC) needed to dry the watermelon rind at this temperature and the CO2 emissions were 609 kWh.kg-1 and 318 kg CO2.kWh-1, respectively. Using the type II SAH, this energy amount would be saved without CO2 emissions. To reach higher drying temperatures the combination of the SAH and the electrical convective dryer is possible.

Minimization of the adverse environmental effects of discarded onions by avoiding disposal through dehydration and food-use.

Onion is a commonly used vegetable in the Cuyo Region, Argentina, and important in the world global vegetable production ranking. Production levels often exceed immediate markets of fresh sale, and excesses, although still edible, are currently discarded (mostly incinerated and disposed in landfill, creating numerous environmental hazards). To minimize these adverse environmental problems, this research investigates upgrading the discarded products by dehydration, hence guaranteeing their ultimate food-use. The dehydration process of discarded onion cv. Crioula Roxa was hence studied at 60 and 70 °C, temperatures selected to maintain the main physicochemical characteristics of the onions, while also creating optimum heat and mass transfer coefficients while significantly reducing the energy consumption and CO2 emissions. When using an electrically-heated convective dryer, the Specific Energy Consumption (SEC) values and the CO2 emissions during dehydration at 70 °C are 738.89 kWh.kg-1 and 264.74 kg of CO2 kg-1, respectively. These values are only 41.61 kWh.kg-1 and 2-4 kg of CO2 kg-1 if a solar dryer is applied. The thermal diffusivities were 1.86✕10-10 m2 s-1 (dehydration) and 1.08✕10-10 m2 s-1 (rehydration), showing a weak effect of the dehydration process on the solid structure and properties.

Non-isothermal drying of bio-wastes: Kinetic analysis and determination of effective moisture diffusivity.

A macro-thermogravimetric analysis (macro-TGA) was applied to analyse the non-isothermal drying of different bio-wastes (quince solid waste, grape marc and pumpkin shell from different enterprises located in San Juan Province, Argentina). The experimental data were obtained at three heating rates (5, 10 and 15 K/min) and two different initial moisture contents (30 and 50% w/w). These data were fitted using the Coats-Redfern and Sharp methods. The D2 model showed the best fitting for all experiments when using the Coats-Redfern method. It is assumed that drying occurs on the solid boundary. The predicted Ea values ranged from 43.60 to 64.50 kJ/mol for the three bio-wastes under the different experimental conditions. The Ea value slightly increases with the increase in heating rate because the wastes require more energy to undergo drying. Deff increases moderately with temperature at the beginning of the dehydration process; then, this increasing behaviour is significant due to the loss of continuous moisture channels. Otherwise, Deff increases with the initial moisture content, showing that the humidity of the samples did not reach the saturation content.

Argentinian pistachio oil and flour: a potential novel approach of pistachio nut utilization.

In order to searching a potential novel approach to pistachio utilization, the chemical and nutritional quality of oil and flour from natural, roasted, and salted roasted pistachios from Argentinian cultivars were evaluated. The pistachio oil has high contents of oleic and linoleic acid (53.5 - 55.3, 29 - 31.4 relative abundance, respectively), tocopherols (896 - 916 µg/g oil), carotenoids (48 - 56 µg/g oil) and chlorophylls (41 - 70 µg/g oil), being a good source for commercial edible oil production. The processing conditions did not affect significantly the fatty acid and minor composition of pistachio oil samples. The content of total phenolic (TP) and flavonoids (FL) was not significantly modified by the roasting process, whereas free radical scavenging (DPPH radical) and antioxidant power decreased in a 20% approximately. Furthermore, salted roasted pistachio flour (SRPF) showed a significant decrease in TP and FL content in comparison to others samples. The phenolic profile of pistachio flours evaluated by LC-ESI-QTOF-MS. The major compounds identified were (+)-catechin (38 - 65.6 µg/g PF d.w.), gallic acid (23 - 36 µg/g PF d.w.) and cyanidin-3-O-galactoside (21 - 23 µg/g PF d.w.). The treatments effects on the phenolics constituents of pistachio flour. Roasting caused a significant reduction of some phenolics, gallic acid and (+)- catechin, and increased others, naringenin and luteolin. Salting and roasting of pistachio increased garlic acid and naringenin content.

In order to searching a potential novel approach to pistachio utilization, the chemical and nutritional quality of oil and flour from natural, roasted, and salted roasted pistachios from Argentinian cultivars were evaluated. The pistachio oil has high contents of oleic and linoleic acid (53.5­55.3, 29­31.4 relative abundance, respectively), tocopherols (896­916 µg/g oil), carotenoids (48­56 µg/g oil) and chlorophylls (41­70 µg/g oil), being a good source for commercial edible oil production. The processing conditions did not affect significantly the fatty acid distribution and minor components of pistachio oil samples. The roasting process not diminish total phenolic (TP) and flavonoids (FL) content significantly compared to natural pistachio flour (NPF), even so reduced the DPPH antioxidant capacity (approximately 20 %) in the roasted pistachio flour (RPF). Furthermore, salted roasted pistachio flour (SRPF) showed a slight and significant decrease on TP and FL content in relation to the others samples. The phenolic profile of pistachio flours were evaluated by LC-ESI-QTOF-MS. The major compounds were (+)-catechin (38­65.6 µg/g PF d.w.), gallic acid (23­36 µg/g PF d.w.) and cyanidin-3-O-galactoside (21­23 µg/g PF d.w.). The treatments have different effects on the phenolics constituents of pistachio flour. Roasting caused a significant reduction of some phenolics, gallic acid and (+)-catechin, and increased others, naringenin and luteolin. Otherwise, salting and roasting of pistachio increased levels of gallic acid and naringenin. These results suggest that Argentinian pistachio oil and flour could be considered as ingredients into applications that enhance human health.

Enzymatic activities produced by mixed Saccharomyces and non-Saccharomyces cultures: relationship with wine volatile composition.

During certain wine fermentation processes, yeasts, and mainly non-Saccharomyces strains, produce and secrete enzymes such as ß-glucosidases, proteases, pectinases, xylanases and amylases. The effects of enzyme activity on the aromatic quality of wines during grape juice fermentation, using different co-inoculation strategies of non-Saccharomyces and Saccharomyces cerevisiae yeasts, were assessed in the current study. Three strains with appropriate enological performance and high enzymatic activities, BSc562 (S. cerevisiae), BDv566 (Debaryomyces vanrijiae) and BCs403 (Candida sake), were assayed in pure and mixed Saccharomyces/non-Saccharomyces cultures. ß-Glucosidase, pectinase, protease, xylanase and amylase activities were quantified during fermentations. The aromatic profile of pure and mixed cultures was determined at the end of each fermentation. In mixed cultures, non-Saccharomyces species were detected until day 4-5 of the fermentation process, and highest populations were observed in MSD2 (10% S. cerevisiae/90% D. vanrijiae) and MSC1 (1% S. cerevisiae/99% C. sake). According to correlation and multivariate analysis, MSD2 presented the highest concentrations of terpenes and higher alcohols which were associated with pectinase, amylase and xylanase activities. On the other hand, MSC1 high levels of ß-glucosidase, proteolytic and xylanolytic activities were correlated to esters and fatty acids. Our study contributes to a better understanding of the effect of enzymatic activities by yeasts on compound transformations that occur during wine fermentation.