Effects of microwave heating on the chemical composition and bioactivity of orange juice-milk beverages

Effect of continuous microwave processing on enzymes and quality attributes of bael beverage

Bael (Aegle marmelos) beverage was pasteurized using continuous-microwave (MW) and traditional thermal processing and the activity of native enzymes, pulp-hydrolyzing enzymes, bioactive, physicochemical, and sensory properties were analyzed. First-order and linear biphasic models fitted well (R2 ≥ 0.90) for enzyme inactivation and bioactive alteration kinetics, respectively. For the most resistant enzyme, polyphenoloxidase (PPO), the inactivation target of ≥ 90 % was achieved at 90 °C TMW (final temperature under MW) and 95 °C for 5 min (conventional thermal). MW treatment displayed faster enzyme inactivation and better retention of TPC and AOC. MW treatment at 90 °C TMW showed 5.3 min D-value, 90% total carotenoid content, 3.42 crisp sensory score (out of 5), and no or minor change in physicochemical attributes. Thermal and MW treatment caused the loss of 14 and 10 bioactive compounds, respectively. The secondary and tertiary structural modifications of PPO enzyme-protein revealed MW's lethality primarily due to its thermal effects.

Effects of chitosan molecular weight and mass ratio with natural blue phycocyanin on physiochemical and structural stability of protein

Phycocyanin (PC), an algae-extracted colorant, has extensive applications for its water-solubility and fresh blue shade. When PC is added to acidified media, dispersions are prone to aggregate and decolorize into cloudy systems. For palliating this matter, chitosan with high, medium, and low molecular weights (HMC, MMC, and LMC) were adopted in PC dispersions, and their protective effects were compared based on physiochemical stabilities. The optimal mass ratio between chitosan and PC was identified as 1:5 based on preliminary evaluations and was supported by the higher ζ-potential (31.0-32.1 mV), lower turbidity (39.6-43.6 NTU), and polyacrylamide gel electrophoresis results. Through interfacial and antioxidant capacity analyses, LMC was found to display a higher affinity to PC, which was also confirmed by SEM images and the maximum increase in transition temperature of their complex (155.70 °C) in DSC measurements. The mechanism of electrostatic interaction reinforced by hydrophobic effects and hydrogen bonding was elucidated by FT-IR and Raman spectroscopy. Further comprehensive stability evaluations revealed that, without light exposure, LMC kept PC from internal secondary structure to external blueness luster to the maximum extent. While with light exposure, LMC was not so flexible as HMC, to protect chromophores from attack of free radicals.

Effects of Processing Conditions and Simulated Digestion In Vitro on the Antioxidant Activity, Inhibition of Xanthine Oxidase and Bioaccessibility of Epicatechin Gallate

The bioactivity and gastrointestinal stability of epicatechin gallate (ECG) may be affected by processing conditions. Results showed that the antioxidant ability and inhibitory activity on xanthine oxidase (XO) of ECG were higher at low pH values. Appropriate microwave and heating treatments improved the antioxidant (the scavenging rate increased from 71.75% to 92.71% and 80.88% under the microwave and heating treatments) and XO inhibitory activity (the inhibitory rate increased from 47.11% to 56.89% and 51.85% at the microwave and heating treatments) of ECG. The treated ECG led to a more compact structure of XO. Moreover, there may be synergistic antioxidant and inhibitory effects between ECG and its degradation products. The bioaccessibility of ECG after simulated digestion was untreated > microwave > heating, and the microwave-treated ECG still had good XO inhibitory activity after digestion. These findings may provide some significant information for the development of functional foods enriched in catechins.

Factors affecting aroma compounds in orange juice and their sensory perception: A review

Orange juice is the most widely consumed fruit juice globally because of its pleasant aromas and high nutritional value. Aromas, contributed by free and bound aroma compounds, are an important attribute and determine the quality of orange juice and consumer choices. Aldehydes, alcohols, esters, and terpenoids have been shown to play important roles in the aroma quality of orange juice. Many factors affect the aroma compounds in orange juice, such as genetic makeup, maturity, processing, matrix compounds, packaging, and storage. This paper reviews identified aroma compounds in free and bound form, the biosynthetic pathways of aroma-active compounds, and factors affecting aroma from a molecular perspective. This review also outlines the effect of variations in aroma on the sensory profile of orange juice and discusses the sensory perception pathways in human systems. Sensory perception of aromas is affected by aroma variations but also converges with taste perception. This review could provide critical information for further research on the aromas of orange juice and their manipulation during the development of products.

Improved Phenolic Profile, Sensory Acceptability, and Storage Stability of Strawberry Decoction Beverages Added with Blueberry Decoctions

Blueberries are rich in polyphenols, anthocyanins, and proanthocyanidins; however, they are expensive. In contrast, strawberries have a lower cost and are rich in ellagitannins. Therefore, a strawberry–blueberry blend decoction could produce a low-cost beverage with a rich and diverse phytochemical profile. In this study, we developed three berry-based beverages: blend strawberry–blueberry (SBB), strawberry (SB), and blueberry (BB). The polyphenol profile of the beverages was characterized by UPLC-ESI-Q-ToF MSE, an acceptability test was carried out with potential consumers, and a stability analysis was performed under commercial storage conditions (4, 25, and 34 °C). The SBB exhibited a good sensorial preference (score of 81.3) and showed high contents and a diverse composition of anthocyanins and proanthocyanidins, which were up to 3.0- and 1.2-fold higher compared to the SB, respectively. Regarding the storage stability, the SBB showed better retention of lightness (97.9%) and red color (66.7%) at the end of the storage under refrigerated conditions (4 °C) compared to the SB. Therefore, these results demonstrate that using blended berry fruits leads to the creation of a functional beverage that has higher nutraceutical potential than single-berry-based beverages.

Comprehensive evaluation of the effect of five sterilization methods on the quality of black carrot juice based on PCA, TOPSIS and GRA models

The effect of thermal pasteurization (TP), high temperature long time (HTLT), ultra-high temperature instantaneous (UHT), high hydrostatic pressure (HHP) and thermosonication (TS) sterilization on the physicochemical, sensory and functional properties of black carrot juice (BCJ) were studied. And for the first time, the comprehensive quality of sterilized BCJ was quantified by mathematical modeling. UHT was the least suitable sterilization method for BCJ resulting from the most severe deterioration in functional properties. TS had adverse effects on sensory and physicochemical properties, but significantly increased the total flavonoids and anthocyanins contents (p < 0.05) and showed the strongest antioxidant activity, making it a nutritional high-value processing method. TP and HHP balanced the improvement of sensory properties and the retention of functional properties, which were the most suitable sterilization methods for BCJ. This study determined the optimal sterilization methods of BCJ, and provided a scientific solution for the screening of high quality processing methods.

Innovative Processing Technologies to Develop a New Segment of Functional Citrus-Based Beverages: Current and Future Trends

The food industries are interested in developing functional products due to their popularity within nutritional and healthy circles. Functional fruit-based beverages represent one of the fast-growing markets due to the high concentrations of bioactive compounds (BCs), which can be health promoters. Hence, functional beverages based on citrus fruits are a potential way to take advantage of their nutritional and bioactive properties that could attract the interest of consumers. In order to ensure microbial and quality stability, the beverages are subjected to preservation treatment; however, the application of high temperatures leads to the loss of thermolabile BCs. Nowadays, innovative processing technologies (IPT) such as pulsed electric field (PEF), high-pressure processing (HPP), ultrasound processing (US), ohmic heating (OH), and microwave (MW) are a promising alternative due to their efficiency and low impact on juice BCs. The available literature concerning the effects of these technologies in functional fruit-based beverages is scarce; thus, this review gathers the most relevant information about the main positive and negative aspects of the IPT in functional properties, safety, and consumer acceptance of functional citrus-based beverages, as well as the use of citrus by-products to promote the circular economy in citrus processing.

Citrus juice off-flavor during different processing and storage: Review of odorants, formation pathways, and analytical techniques

As the most widespread juice produced and consumed globally, citrus juice (mandarin juice, orange juice, and grapefruit juice) is appreciated for its attractive and distinct aroma. While the decrease of characteristic aroma-active compounds and the formation of off-flavor compounds are easy to occur in processing and storage conditions. This review provides a comprehensive literature of recent research and discovery on citrus juice off-flavor, primarily focusing on off-flavor compounds induced during processing and storage (i.e., thermal, storage, light, oxygen, package, fruit maturity, diseases, centrifugal pretreatment, and debittering process), formation pathways (i.e., terpene acid-catalyzed hydration, caramelization reaction, Maillard reaction, Strecker degradation, and other oxidative degradation) of the off-flavor compounds, effective inhibitor pathway to off-flavor (i.e., electrical treatments, high pressure processing, microwave processing, ultrasound processing, and chemical treatment), as well as odor assessment techniques based on molecular sensory science. The possible precursors (terpenes, sulfur-containing amino acids, carbohydrates, carotenoids, vitamins, and phenolic acids) of citrus juice off-flavor are listed and are also proposed. This review intends to unravel the regularities of aroma variations and even off-flavor formation of citrus juice during processing and storage. Future aroma analysis techniques will evolve toward a colorimetric sensor array for odor visualization to obtain a "marker" of off-flavor in citrus juice.

Toward in-process technology-aided automation for enhanced microbial food safety and quality assurance in milk and beverages processing

Ensuring the safety of food products is critical to food production and processing. In food processing and production, several standard guidelines are implemented to achieve acceptable food quality and safety. This notwithstanding, due to human limitations, processed foods are often contaminated either with microorganisms, microbial byproducts, or chemical agents, resulting in the compromise of product quality with far-reaching consequences including foodborne diseases, food intoxication, and food recall. Transitioning from manual food processing to automation-aided food processing (smart food processing) which is guided by artificial intelligence will guarantee the safety and quality of food. However, this will require huge investments in terms of resources, technologies, and expertise. This study reviews the potential of artificial intelligence in food processing. In addition, it presents the technologies and methods with potential applications in implementing automated technology-aided processing. A conceptual design for an automated food processing line comprised of various operational layers and processes targeted at enhancing the microbial safety and quality assurance of liquid foods such as milk and beverages is elaborated.

Preparation of anthocyanin-rich mulberry juice by microwave-ultrasonic combined pretreatment

The work aims to study the process of microwave-ultrasonic combined treatment to obtain anthocyanin-rich mulberry juice. A Box-Behnken design was employed to analyze the effects of microwave time and citric acid content on the total phenol content, total anthocyanin content, hue, color intensity, DPPH and ABTS radical scavenging activities. Under the optimum conditions (microwave time of 46 s, citric acid addition of 273 mg/kg), the total phenol content, total anthocyanin content, the DPPH and ABTS radical scavenging activities reached 4.24 mg GAE/mL, 3.29 mg C3G/mL, 4.59 mg TE/mL and 11.90 mg TE/mL, respectively. Subsequently, the mulberry juice was processed with ultrasound of different frequencies. It was found that low-frequency ultrasonic treatment (25 kHz) could significantly reduce the loss of total phenolic and anthocyanin monomers and improve the antioxidant capacity of mulberry juice during storage for five weeks. Overall, mulberry juice with microwave-ultrasonic pretreatment is a natural antioxidant.

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.

Removal of difenoconazole and nitenpyram by composite calcium alginate beads during apple juice clarification

A novel genipin crosslinked calcium alginate/chitosan/polydopamine composite beads (g-Alg/CS/PDA) was synthesized for the removal of residual difenoconazole and nitenpyram during the clarification of apple juice. The composite beads with low potential health risks for all of the main materials were natural, green and biocompatible. Since g-Alg/CS/PDA can both clarify and adsorb, pesticide residues could be removed during the clarification of juice without additional steps. The g-Alg/CS/PDA beads were characterized, and the adsorption parameters, including the pesticide residue levels, adsorption time, pH, ionic strength, fructose concentration and adsorbent dose, were optimized. The adsorption data were fitted to the Freundlich isotherm model (R² = 0.9604, 0.9625) and the pseudo-second-order kinetic model (R² = 0.9993, 0.9999). The results indicated that the adsorption behavior of beads was heterogeneous. Moreover, the rate was controlled by several factors. The adsorption mechanism of two pesticides was also discussed. Hydrophobic and π-π conjugation interactions played a dominant role for the adsorption of difenoconazole, while hydrogen bonding and electrostatic interactions were the main factors for nitenpyram.

Microwave applications in the food industry: an overview of recent developments

Microwave radiation has the ability to heat a material with dielectric properties. Material absorbs microwave energy and then converts it into heat, which gives the possibility of a wide use of microwaves in many industry sectors or agricultural sciences. Microwaves are especially widely used in food industry. The main objective of this paper is to present an overview of recent development regarding microwave applications in food industry. Many techniques in food processing (pasteurization, sterilization, drying, thawing, blanching and stunning) are assisted by microwave energy. It should be mentioned also the use of microwaves in nutrients and nutraceuticals production. Waste generation is an integral part of food production. Microwaves have also application in wastes management. The results of experiments, factors affecting heating and their practical application have been discussed. Many cases have been compared with conventional process methods. The use of microwaves shows many advantages. The most important aspect is shortening the time of the thermal process (even by 50%) and reducing the costs of the operation. In addition, it allows to increase the efficiency of processes while maintaining high quality. The examples of microwave applications given in the article are environmentally- friendly because the conditions of thermal processing allow for reducing the use of solvents and the amount of sewage by decreasing the demand for water. It is anticipated that microwaves will become increasingly popular, with the development of new microwave technologies solving many problems in the future.