Environmentally Friendly Approach to Pectin Extraction from Grapefruit Peel: Microwave-Assisted High-Pressure CO2/H2O

In this research, pectin extraction from grapefruit peel (GPP) was performed using a microwave-assisted high-pressure CO2/H2O (MW-HPCO2) system. The Box-Behnken design of response surface methodology was applied for the optimization of MW-HPCO2 extraction conditions to obtain the highest pectin yield. The effects of temperature, time, and liquid/solid ratio on pectin yield were examined in the range of 100-150 °C, 5-15 min, and 10-20 mL g-1, respectively. Under the optimum extraction conditions (147 °C, 3 min, and 10 mL g-1), pectin was obtained with a yield of 27.53%. The results obtained showed that the extraction temperature and time had a strong effect on the pectin yield, while the effect of the liquid/solid ratio was not significant, and the pectin was effectively extracted from grapefruit peel (GP) using MW-HPCO2. Additionally, the application of GPP in apricot jam showed that MW-HPCO2-GPP can be used as a thickener in the food industry. The yield and physicochemical properties (ash, protein, galacturonic acid, reducing sugar and methoxyl content, degree of esterification, equivalent weight, color, viscosity) of pectin extracted in the optimum conditions of the MW-HPCO2 method were superior to pectin extracted by the traditional method. The results of this study revealed that MW-HPCO2 could be an innovative green and rapid technique for pectin extraction.

The green novel approach in hydrolysis of pistachio shell into xylose by microwave-assisted high-pressure CO2 /H2 O

BACKGROUND

Pistachio shell is a valuable lignocellulosic biomass because almost 90% of its hemicellulose fraction is xylan, which can be converted into high value-added compounds such as xylooligosaccarides, xylose, xylitol and furfural. The present study represents a green and novel approach to produce xylose from lignocellulosic biomass. Microwave-assisted high-pressure CO2 /H2 O hydrolysis (MW-HPCO2 ) comprising a combination never previously used was performed to produce xylose from pistachio shell.

RESULTS

Response surface methodology with a Box-Behnken design was implemented to optimize microwave-assisted high-pressure CO2 /H2 O hydrolysis (MW-HPCO2 ). The effect of temperature, time and liquid-to-solid ratio was studied in the ranges of 180-210 °C, 10-30 min and 5-30 mL g-1 , respectively. A maximum xylose yield of 61.39% and minimum degradation compounds (5-hydroxymethyl furfural and furfural) of 11.07% were attained under reaction conditions of 190 °C, 30 min and 18 mL g-1 .

CONCLUSION

The results showed that hydrolysis temperature, time and liquid-to-solid ratio had a strong influence on the xylose yield, as well as on the formation of degradation compounds. MW-HPCO2 significantly increased accessibility to cellulose-derived products in the subsequent enzymatic hydrolysis. The results of the present study reveal that MW-HPCO2 can be a promising green technique for the hydrolysis of lignocellulosic biomass. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Hot-Air-Assisted Radiofrequency Drying of Olive Pomace and Its Effect on the Quality of Olive Pomace Oil

In this study, the drying of olive pomace in a hot-air-assisted radio frequency system (HA-RF) was conducted, and its effects on crude olive pomace oil quality were investigated. In this respect, the effects of radiofrequency electrode distance (90, 105 and 120 mm), sample thickness (2.5, 5, 7.5 and 10 cm) and compaction density (~0.45, ~0.60 and ~0.82 g/cm3) on drying rate have been evaluated. The best drying, with a higher drying efficiency, was obtained with 1 kg of sample weight and a 10 cm product thickness, ~0.45 g/cm3 compaction density and 105 mm electrode distance. Moreover, the results showed that the compaction density significantly affects the drying rate. The drying time was prolonged by approximately four times by increasing the compaction density from ~0.45 to ~0.82 g/cm3. The drying rate of olive pomace in HA-RF drying was compared with drying performed using hot air (HA) and radiofrequency (RF). The results revealed that HA-RF application reduced the drying time by almost 1.7 times compared to hot air drying and by about 2.7 times compared to radiofrequency. The peroxide value, free fatty acid content, p-anisidine value, polyaromatic hydrocarbon content, L*, a*, b*, chlorophyll and total carotenoid content of the oil extracted from the olive pomace dried under the best drying conditions were 1.09%, 12.2 meq O2/kg oil, 3.01, <1 ppb, 38.6, 7.5, 62.56, 105.25 mg pheophytin a/kg oil, 2.85 mg/kg oil, respectively. The drying of olive pomace in a hot-air-assisted radio frequency system could be an alternative way to ensure the safe and rapid drying of olive pomace.

Effect of Encapsulation Techniques on Aroma Retention of Pistacia terebinthus L. Fruit Oil: Spray Drying, Spray Freeze Drying, and Freeze Drying

The primary aim of this investigation was to assess the impact of varying the ratio of gum arabic to maltodextrin and employing diverse encapsulation techniques on the properties of the powdered substance and the capacity to retain the aromatic attributes of terebinth fruit oil. Distinct ratios of gum arabic to maltodextrin (75:25, 50:50, and 25:75) were employed to fabricate oil-in-water emulsions. The utmost stability of the emulsion was realized at a gum arabic to maltodextrin ratio of 75:25, characterized by a minimal creaming index and an even and small-scale dispersion. The encapsulation techniques employed included spray drying (SD), spray freeze-drying (SFD), and freeze-drying (FD). These methodologies were compared based on encapsulation efficiency, desiccation yield, powder attributes, and the capacity to retain aroma. The encapsulation efficiencies were notably higher (>90%) in SD, particularly with the application of an ultrasonic nozzle and a two-fluidized nozzle (2FN), in contrast to those obtained through SFD and FD. Notably, SD employing an ultrasonic nozzle exhibited superior preservation of volatiles (73.19%) compared to FD (24.45%), SD-2FN (62.34%), and SFD (14.23%). Among the various components, α-pinene and linalool stood out with near-perfect retention rates, close to 100%.

Hot air-assisted radio frequency drying of grated potato (Solanum tuberosum L.): Drying behavior and the associated effect on characteristics of potato flour

In this study, drying of grated potato in a hot air-assisted radio frequency system (HA-RF) and the associated effects on the final potato flour quality were studied. The drying behavior of the grated potatoes at different electrode distances (70-90 mm) and sample thickness (2-4 cm) was investigated. The safe drying (without burning tendency) of the maximum amount of sample (1000 g) in a reasonable drying time was carried out at 80 mm of electrode gap and 4 cm of sample thickness. HA-RF drying kinetics were studied and compared with hot air (HA) and radio frequency (RF) (without hot air) drying methods. HA-RF drying increased drying rate and shortened drying time by about 58% and 70% compared to HA and RF drying, respectively. The properties of the final potato flour obtained after HA-RF drying were also compared with those produced by RF, HA, and freeze drying. The flour obtained by HA-RF was superior to RF and HA dried samples with better retention of cellular microstructure and color. The drying method significantly affected the functional properties, thermal characteristics, pasting properties, and other characteristics of potato flours. PRACTICAL APPLICATION: HA-RF as an alternative drying technology was used for the first time to produce potato flour. The functional, thermal, and structural properties of the HA-RF dried product were compared with those dried by HA, RF, and freeze drying. The results of this study ensured very useful information for the use of potato flour obtained by different drying methods in the development of products with specific functional and rheological properties.

Pistachio hull as an alternative pectin source: its extraction and use in oil in water emulsion system

In this study, pectin was extracted from the pistachio hull using two methods: conventional extraction and ultrasound-assisted extraction. Water and citric acid solution were tested separately as extraction solvents in both conventional and ultrasound methods. The highest yield (32.3 ± 1.44%) was obtained using a citric acid solution in the conventional extraction method. The pectin extracted with this method had 38.94 g acid per 100 g dry pectin extract. The galacturonic acid and ash contents were 65.81 ± 1.51 and 1.57 ± 0.03%, respectively. The pistachio hull pectin was under the low methoxy pectin group with a 19.29 ± 0.41% degree of esterification. The emulsifying property of the pectin extracted was investigated in an oil-in-water emulsion system at six different pectin concentrations (2, 4, 5, 6, 8, and 10% w/w) and at a fixed oil ratio (20% w/w). Emulsion performance was investigated in terms of emulsion stability, microstructural characteristics, droplet size, and rheological properties. The most stable emulsion was obtained at a 6% pectin concentration. The emulsifying activity index, emulsion stability index, droplet size, consistency index, and flow behavior index were 172.85 ± 0.59 m²/g, 158.28 ± 3.41 min, 6.08 ± 0.04 µm, 0.72 ± 0.001 Pa·sⁿ, and 0.752 ± 0.005 at this concentration, respectively.

Effect of sequential-combined solar energy assisted hot air and hot air assisted radio frequency drying on the physical and chemical properties of dried apricots

Quality characteristics of sulphured and non-sulphured apricots dried with a sequential combined pilot scale solar assisted hot air and hot air assisted radio frequency dryer and conventional sun system were compared. The combined drying approach showed improved color, hardness, antioxidant activity and retention of vitamin C, β-carotene and total phenolic content values compared to conventional sun drying both for sulphured and non-sulphured samples. The effects of sulphur concentration and addition of pistachio hull extract as a treatment prior to drying were also investigated. Increase in sulphur concentration and addition of extract resulted in considerable quality (with respect to color, Vitamin C, β-carotene and total phenolic content) increase in apricots. The apricots pretreated with extract had the highest total phenolic content and antioxidant activity. This study demonstrated that combined drying process is an effective drying method for apricots with the better preservation of product quality attributes.

A Novel Modified Lipid: Enzymatic Esterification of 2-Monoacylglycerol with N-acetyl-l-leucine

The objective of this research was to synthesize and characterize a novel modified lipid which is composed of mainly oleic acid at sn-2 position and a hydrophobic essential amino acid derivative (N-acetyl-l-leucine) at sn-1(3) or sn-1, 3 positions. LC-MS-MS analysis indicated that the target modified lipid structure was obtained at the end of the developed reaction. Response surface methodology was applied to enhance a reliable empirical model for prediction and to optimize reaction conditions: reaction time (8 to 24 hr), reaction temperature (40 to 55 °C), and enzyme load (15 to 30 wt%). The percentage of total reaction products was found to be 28.5 at the optimum conditions of 54 °C, 8 hr and 15% (by mass) enzyme load. This result is closely correlated to the predicted highest total reaction product (29.3%) obtained by response surface methodology. The physical and thermal characteristics of the modified lipid and refined olive pomace oil were compared and found to be similar. Caloric value of modified lipid was decreased by 18.65% compared to that of refined olive pomace oil. A novel modified lipid which may have potential uses in healthy food industries was successfully produced with the incorporation of N-acetyl-l-leucine to 2-monoacylglycerol.

PRACTICAL APPLICATION

A novel modified lipid was synthesized by enzymatic incorporation of a "hydrophobic and essential amino acid derivative" into 2-monoacylglycerol. This modified lipid contains mainly oleic acid at sn-2 position and N-acetyl-l-leucine at sn-1,3 positions. The product behaved as an oil above 10 °C. Caloric value of the novel oil-like product was reduced by 18.65%. The modified lipid may have the potential for replacement with the oil in food products such as margarine, shortenings, salad dressing, and mayonnaise.

Optimisation of Microwave-Assisted Extraction of Pomegranate (Punica granatum L.) Seed Oil and Evaluation of Its Physicochemical and Bioactive Properties

Pomegranate seed oil was extracted in a closed-vessel high-pressure microwave system. The characteristics of the obtained oil, such as fatty acid composition, free fatty acidity, total phenolic content, antioxidant activity and colour, were compared to those of the oil obtained by cold solvent extraction. Response surface methodology was applied to optimise extraction conditions: power (176-300 W), time (5-20 min), particle size (d=0.125-0.800 mm) and solvent to sample ratio (2:1, 6:1 and 10:1, by mass). The predicted highest extraction yield (35.19%) was obtained using microwave power of 220 W, particle size in the range of d=0.125-0.450 mm and solvent-to-sample ratio of 10:1 (by mass) in 5 min extraction time. Microwave-assisted solvent extraction (MASE) resulted in higher extraction yield than that of Soxhlet (34.70% in 8 h) or cold (17.50% in 8 h) extraction. The dominant fatty acid of pomegranate seed oil was punicic acid (86%) irrespective of the extraction method. Oil obtained by MASE had better physicochemical properties, total phenolic content and antioxidant activity than the oil obtained by cold solvent extraction.