Microwave processing of camu‐camu juices: Physicochemical and microbiological parameters

Processing of verjuice by ultrasound-assisted microwave heating: An assessment on the enzyme activity retention, technological parameters, and bioactive properties

The present study evaluated the effect of ultrasonication prior to microwave heating applied at 60 °C, 70 °C, and 80 °C on the quality characteristics of verjuice. The sole microwave heating and conventional heating were also performed at the same temperature levels, and effectiveness of three different treatments were evaluated. The required treatment times were decided based on obtaining <10% pectin methylesterase (PME) activity, and ultrasound pretreatment provided the least heating durations. Turbidity, browning index, and viscosity values increased by 3.4 to 14.8-fold, 0.24 to 1.26-fold, and 9.2% to 48.0%, respectively, after all thermal treatments, while Brix values decreased by 1.4% to 15.7%. Ultrasound pretreatment revealed relatively lower browning index in all temperature levels, and almost the highest viscosity values were obtained in sonication pretreated microwave heating as compared with sole microwave and conventional heating. The minimum turbidity value (0.035) was determined in ultrasound-assisted microwave heating at 60 °C. The highest antioxidant capacity (DPPH and ABTS) values were achieved by ultrasound-assisted microwave heating (up to 4.96 and 28.4 mmol Trolox equivalent (TE)/kg, respectively) followed by microwave heating (up to 4.30 and 27.0 mmol TE/kg) and conventional heating (up to 3.72 and 26.8 mmol TE/kg). Furthermore, ultrasonication resulted in better retentions of PME residual activity during 60 days of refrigerated storage (4 °C). Ultrasound pretreatment prior to microwave heating could be a convenient approach for juice processing by reducing the required treatment time and by conserving the quality parameters.

Cold plasma as a pre-treatment for processing improvement in food: A review

Thermal processes can be very damaging to the nutritional and sensory quality of foods. Non-thermal technologies have been applied to reduce the impact of heat on food, reducing processing time and increasing its efficiency. Among many non-thermal technologies, cold plasma is an emerging technology with several potential applications in food processing. This technique can be used to preserve and sanitize food products, and act as a pre-treatment for drying, extraction, cooking, curing, and hydrogenation of foods. Furthermore, the reacting plasma species formed during the plasma application can change positively the sensory and nutritional aspects of foods. The aim of this review is to analyze the main findings on the application of cold plasma as a pre-treatment technology to improve food processing. In its current maturity stage, the cold plasma technology is suitable for reducing drying time, increasing extraction efficiency, as well as curing meats. This technology can convert unsaturated into saturated fats, without forming trans isomers, which can be an alternative to healthier foods. Although many advantages come from cold plasma applications, this technology still has several challenges, such as the scaling up, especially in increasing productivity and treating foods with large formats. Optimization and control of the effects of plasma on nutritional and sensory quality are still under investigation. Further improvement of the technology will come with a higher knowledge of the effects of plasma on the different chemical groups present in foods, and with the development of bigger or more powerful plasma systems.

Quality Evaluation of Lemon Cordial Stored at Different Times with Microwave Heating (Pasteurization)

Consumer interest in food quality and safety has shifted over time, as consumers increasingly prefer minimally processed items. As a result, numerous non-thermal approaches have been implemented due to their potential to preserve the nutritional profile of products along with lengthening their storability. Microwaving, a green processing technique, volumetrically heats the product because of the interactions developed between charged ions, polar water molecules of foodstuff and the incoming electromagnetic waves. The study was mapped out to investigate the effect of microwave exposure time (60, 90 and 120 s) at fixed power (1000 W) and frequency (2450 MHz) on physicochemical properties, phytochemical constituents, antioxidant potential and microbial counts of lemon cordial stored at refrigerated temperature (4 ± 2 °C). The mentioned parameters were analyzed after an interval of 30–90 days. Statistical findings illustrated a highly significant (p ≤ 0.01) impact of microwave treatment and storage on titratable acidity, pH, total soluble solids, total phenolic contents, total flavonoids contents, antioxidant potential and total plate count. Sample microwaved for 120 s showed the highest pH values (2.45 ± 0.050), total soluble solids (56.68 ± 2.612 °B) and antioxidant activity (1212.03 ± 716.5 µg—equivalent of ascorbic acid per 100 mL of cordial); meanwhile, it exhibited the lowest total plate counts (1.75 ± 0.144 Log 10 CFU/mL). Therefore, microwaving can be suggested as a suitable alternate to traditional pasteurization techniques as well as to chemical preservatives.

Improvement of the bioaccessibility of bioactive compounds from Amazon fruits treated using high energy ultrasound

The aim of this paper was to evaluate the effect of high energy ultrasound on the bioaccessibility of bioactive compounds from açaí (Euterpe precatoria) and buriti (Mauritia flexuosa) juices. Five levels of energy density (0, 0.9, 1.8, 2.7 and 3.6 J.cm^-3), as well as their effects on the bioactive compounds were evaluated. Ultrasound did not significantly influence pH, titratable acidity and soluble solids. However, it affected the color attributes of juices by increasing brightness and color variation. The concentration of bioactive compounds (anthocyanins and carotenoids) and antioxidants increased with increasing ultrasound energy density, which was confirmed by Principal Component Analysis (PCA). Fatty acids increased up to 2.7 J.cm^-3 and were reduced when higher energy was employed on the ultrasound process. Ultrasound allowed the release of new aromatic substances. For this reason, the ultrasound technology can be considered an alternative pre-treatment for fruit juices, improving the bioaccessibility and concentration of bioactive compounds.

Camu-camu bioactive compounds extraction by ecofriendly sequential processes (ultrasound assisted extraction and reverse osmosis)

Technical feasibility of an ecofriendly sequential process (ultrasound assisted extraction and reverse osmosis, or UAE and RO) was evaluated in order to obtain a functional Camu-camu (Myrciaria dubia) product with high vitamin C content. Water was used in the assisted extraction by probe ultrasound (UAE) in an experimental design to evaluate different times, amplitudes and temperatures. The best region for total phenolic (TP) and vitamin C (VC) extraction was 5 min, 60 °C and 30% amplitude. Following extraction, the sample was concentrated by reverse osmosis (R25a, 500 Da, polyamide, and 5 bar area 3 ft2), obtaining a relatively low fouling of 19%. At the end of the sequential process (by HPLC-DAD/UV vis), was obtained a concentrated camu-camu (CC) with high Vitamin C (52.01 ± 0.889 mg/g) and cyanidin-3-glucoside, being respectively 7.0 and 4.5 times higher; also the concentration of phenolic compounds was increased by 3.2 times (25.798 mg GAE/g), and anthocyanins in 6.5 times (66.169 mg of cyanidin-3-glucoside/100 g) as well as high antioxidant activity by all three methods evaluated (increased 3.0, 4.6 and 2.38 times for ABTS, DPPH, FRAP, respectively) by comparing the CC with the initial extract (CS). Twenty compounds were identified by UHPLC-QTOF-MS/MS, highlighting quercetin, gallic acid, p- coumaric, ellagic acid and cyanidin-3-glucoside, and at the first time alnusiin was detected in camu-camu. Therefore, the combination of ultrasound assisted extraction and reverse osmosis can be a promising profitable alternative in order to apply bioactive compounds in food, nutraceuticals and cosmetic matrices, bringing their benefits to consumers.

Dielectric barrier atmospheric cold plasma applied on camu-camu juice processing: Effect of the excitation frequency

The aim of this paper was to evaluate the effect of cold plasma excitation frequency on camu-camu juice processing. Different levels of frequency (200, 420, 583, 698 and 960 Hz) were applied on camu-camu juice to measure the contents of ascorbic acid and anthocyanins, as well as to evaluate the antioxidant compounds (DPPH, ABTS, FRAP and phenolic compounds), peroxidase and polyphenol oxidase enzymatic activity and color. Furthermore, the juice bioaccessibility was evaluated after simulated digestion. The ascorbic acid concentration was increased when higher excitation frequencies were employed, increasing their bioavailability. Anthocyanins, peroxidase and polyphenol oxidase presented considerable degradation with increasing the plasma excitation frequency. For this reason, the juice processing proposed herein represents an alternative to enhance its nutritional quality. Moreover, the use of cold plasma reduced the activity concentration of endogenous enzymes, presenting considerable degradation for higher excitation frequency.