Comparison of chemical, physical, and ultrasound treatments on the shelf life of fresh‐cut quince fruit ( Cydonia oblonga Mill.)

Production and evaluation of total phenolics, antioxidant activity, viscosity, color, and sensory attributes of quince tea infusion: Effects of drying method, sonication, and brewing process

This study aimed to examine the influence of drying approaches (convective and infrared (IR)), sonication, and brewing time on the total phenolic content (TPC), antioxidant activity (AA), viscosity, color indexes, and sensory attributes of quince tea infusion (QTI). The AA and TPC in the QTI dried in the IR dryer were higher than in the convective dryer. The TPC and AA of QTI prepared by convective and IR dryers increased when the ultrasound treatment and brewing time were increased. In terms of viscosity and Brix, there was no differences between the QTIs and the average viscosity and density of the samples were 1.79 ± 0.28 mPa.s and 3.18 ± 0.07°Brix, respectively. The QTI prepared by the IR has a reddish-brown hue (higher a* value), but the samples prepared with the convective dryer were yellow (higher b* value). The sensory attributes scores of QTI prepared by IR were higher than those of convection-dried samples. In general, the use of an IR dryer for drying grated quince, ultrasound treatment for 8 min, and brewing time for 30 min is a promising condition for the production of QTI with higher TPC and AA, and with appropriate color and sensorial acceptance.

Applications of ultrasonication on food enzyme inactivation- recent review report (2017-2022)

Ultrasound processing has been widely applied in food sector for various applications such as decontamination and structural and functional components modifications in food. Enzymes are proteinaceous in nature and are widely used due to its catalytic activity. To mitigate the undesirable effects caused by the enzymes various technologies have been utilized to inactive the enzymes and improve the enzyme efficiency. Ultrasound is an emerging technology that produces acoustic waves which causes rapid formation and collapse of bubbles. It has the capacity to break the hydrogen bonds and interact with the polypeptide chains due to Vander Waals forces leading to the alteration of the secondary and tertiary structure of the enzymes thereby leading to loss in their biological activity. US effectively inactivates various dairy-related enzymes, including alkaline phosphatase (ALP), lactoperoxidase (LPO), and γ-glutamyl transpeptidase (GGTP) with increased US intensity and time without affecting the natural dairy flavors. The review also demonstrates that inactivation of enzymes presents in fruit and vegetables such as polyphenol oxidase (PPO), polygalacturonase (PG), Pectin methyl esterase (PME), and peroxidase. The presence of the enzymes causes detrimental effects causes off-flavors, off-colors, cloudiness, reduction in viscosity of juices, therefore the formation of high-energy free molecules during sonication affects the catalytic function of enzymes and thereby causing inactivation. Therefore this manuscript elucidates the recent advances made in the inactivation of common, enzymes infruits, vegetables and dairy products by the application of ultrasound and also explains the enzyme inactivation kinetics associated. Further this manuscript also discusses the ultrasound with other combined technologies, mechanisms, and its effects on the enzyme inactivation.

Ultrasonic washing as an abiotic elicitor to increase the phenolic content in fruits and vegetables: A review

Ultrasonic washing has been widely applied to the postharvest storage of fruits and vegetables as a residue-free physical washing technology, which plays an important role in improving shelf-life, safety, and nutritional value. Phenolics are a large group of phytochemicals widespread in fruits and vegetables, and they have been considered potential protective factors against some diseases because of potent antioxidative properties. Previous studies have shown that ultrasonic washing can increase the phenolic content of fruits and vegetables immediately or during storage through the induction of plant stress responses, which is of great significance for improving the functional and nutritional value of fruits and vegetables. However, the mechanisms of ultrasound as an elicitor to improve the phenolic content remain controversial. Therefore, this review summarizes the applications of ultrasonic washing to increase the phenolic content in fruits and vegetables. Meanwhile, the corresponding physiological stress response mechanisms of the phenolic accumulation in terms of immediate stress responses (i.e., higher extractability of phenolics) and late stress responses (i.e., metabolism of phenolics) are expounded. Moreover, a hypothetical model is proposed to explain phenolic biosynthesis triggered by signaling molecules produced under ultrasound stress, including primary signal (i.e., extracellular adenosine triphosphate) and secondary signals (e.g., reactive oxygen species, Ca²⁺ , NO, jasmonates, and ethylene). Additionally, the techno-economic feasibility of ultrasonic washing technology is also discussed. Further, challenges and trends for further development of ultrasonic washing as an abiotic elicitor applied to the postharvest storage of fruits and vegetables are presented.

Effect of Ultrasound Combinated with Sodium Hypochlorite Treatment on Microbial Inhibition and Quality of Fresh-Cut Cucumber

The influence of ultrasound combined with sodium hypochlorite (US-NaClO) treatment on microorganisms and quality of fresh-cut cucumber during storage were investigated. Ultrasound (400 W, 40 kHz, US: 5, 10 and 15 min) and sodium hypochlorite (NaClO: 50, 75, 100 ppm) were used to treat fresh-cut cucumber in a single or combined treatment and stored at 4 °C for 8 days and analyzed for texture, color and flavor. The results showed that US-NaClO treatment had a synergistic effect on the inhibition of microorganisms during storage. It could significantly reduce (p < 0.05) the number of microorganisms by 1.73 to 2.17 log CFU/g. In addition, US-NaClO treatment reduced the accumulation of malondialdehyde (MDA) during storage (4.42 nmol/g) and water mobility, and maintained the integrity of the cell membrane, delayed the increase of weight loss (3.21%), reduced water loss, thus slowing down the decline of firmness (9.20%) of fresh-cut cucumber during storage. The degradation of chlorophyll (6.41%) was reduced to maintain the color of freshly cut cucumbers. At the same time, US-NaClO could maintain the content of aldehydes, the main aromatic substance of cucumber, and reduced the content of alcohols and ketones during storage. Combined with the electronic nose results, it could maintain the cucumber flavor at the end of the storage period and reduce the odor produced by microorganisms. Overall, US-NaClO was helpful to inhibit the growth of microorganisms during storage, improve the quality of fresh-cut cucumber.

The effect of supercritical carbon dioxide on the physiochemistry, endogenous enzymes, and nutritional composition of fruit and vegetables and its prospects for industrial application: a overview

Consumers have an increasing demand for fruit and vegetables with high nutritional value worldwide. However, most fruit and vegetables are vulnerable to quality loss and spoilage during processing, transportation, and storage. Among the recently introduced emerging technologies, supercritical carbon dioxide (SCCO2) has been extensively utilized to treat and maintain fruit and vegetables mainly due to its nontoxicity, safety, and environmentally friendly. SCCO2 technology generates low processing costs and mild processing conditions (temperature and pressure) that allow for the application of CO2 at a supercritical state. This review aimed to summarize the current knowledge on the influence of SCCO2 technology on the quality attributes of fruit and vegetable products, such as physicochemical properties (pH, color, cloud, particle size distribution, texture), sensory quality, and nutritional composition (ascorbic acid, phenolic compounds, anthocyanins, carotenoids, and betalains). In addition, the effects and mechanisms of the SCCO2 technique on endogenous enzyme inactivation (polyphenol oxidase, peroxidase, and pectin methylesterase) were also elucidated. Finally, the prospects of the SCCO2 technique for industrial application was discussed from the economic and regulatory aspect.

Ultrasonic washing as an abiotic elicitor to induce the accumulation of phenolics of fresh-cut red cabbages: Effects on storage quality and microbial safety

Ultrasonic washing has been proved to be an abiotic elicitor to induce the accumulation of phenolics in some fruit and vegetables. However, the feasibility of ultrasonic washing on the accumulation of phenolics in fresh-cut red cabbages has not yet been reported. Therefore, the effects of ultrasonic washing on the phenolics and related phenolic metabolism enzymes of fresh-cut red cabbages, as well as quality and microbial safety during cold storage, were investigated. Firstly, the single-factor tests were used to optimize the ultrasonic processing parameters, including frequency mode, frequency amplitude, power density, frequency cycle time, and ultrasonic washing. Then the activities of the enzymes related to phenolic metabolisms after optimal ultrasound treatment were investigated, including phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO), and peroxidase (POD). Additionally, the quality and microbial safety of fresh-cut red cabbages stored at 4°C under the optimal ultrasound treatment were evaluated. The results showed that the content of soluble phenolics (SPs) in fresh-cut red cabbages increased significantly during storage under the optimal conditions (28 ± 2 kHz, 60 W/L, 400 ms, and 20 min) compared with the control (P < 0.05). The PAL activity was activated and the PPO and POD activities were inhibited after ultrasonic washing, which contributed to the increase in the content of SPs. Meanwhile, the storage quality and microbial safety of fresh-cut red cabbages were improved. Ultrasonic washing reduced the weight loss and respiration rate and improved the color and texture characteristics. Additionally, the fresh-cut red cabbages after ultrasonic washing showed more retention of ascorbic acid (AA), total soluble proteins (TSPs), total soluble sugars (TSSs), and total soluble solids (SSs) compared with the control. Finally, ultrasonic washing effectively inhibited the growth of bacteria, molds and yeasts, which is beneficial to the extension of the shelf-life of fresh-cut red cabbages. Therefore, ultrasonic washing can be used as a tool to increase the content of SPs in fresh-cut red cabbages while retaining quality attributes and microbial safety.

Natural Plant Extracts: An Update about Novel Spraying as an Alternative of Chemical Pesticides to Extend the Postharvest Shelf Life of Fruits and Vegetables

Fresh fruits and vegetables, being the source of important vitamins, minerals, and other plant chemicals, are of boundless importance these days. Although in agriculture, the green revolution was a milestone, it was accompanied by the intensive utilization of chemical pesticides. However, chemical pesticides have hazardous effects on human health and the environment. Therefore, increasingly stimulating toward more eco-friendly and safer alternatives to prevent postharvest losses and lead to improving the shelf life of fresh fruits and vegetables. Proposed alternatives, natural plant extracts, are very promising due to their high efficacy. The plant-based extract is from a natural source and has no or few health concerns. Many researchers have elaborated on the harmful effects of synthetic chemicals on human life. People are now much more aware of safety and health concerns than ever before. In the present review, we discussed the latest research on natural alternatives for chemical synthetic pesticides. Considering that the use of plant-based extracts from aloe vera, lemongrass, or neem is non-chemical by-products of the fruits and vegetable industry, they are proved safe for human health and may be integrated with economic strategies. Such natural plant extracts can be a good alternative to chemical pesticides and preservatives.

Uncovering the Industrial Potentials of Lemongrass Essential Oil as a Food Preservative: A Review

The food industry is growing vastly, with an increasing number of food products and the demand of consumers to have safe and pathogen-free food with an extended shelf life for consumption. It is critical to have food safe from pathogenic bacteria, fungi, and unpleasant odors or tastes so that the food may not cause any health risks to consumers. Currently, the direction of food industry has been shifting from synthetically produced preservatives to natural preservatives to lower the unnecessary chemical burden on health. Many new technologies are working on natural prevention tools against food degradation. Lemongrass is one such natural preservative that possesses significant antimicrobial and antioxidant activity. The essential oil of lemongrass contains a series of terpenes that are responsible for these activities. These properties make lemongrass acceptable in the food industry and may fulfill consumer demands. This article provides detailed information about the role of lemongrass and its essential oil in food preservation. The outcomes of the research on lemongrass offer room for its new technological applications in food preservation.

Comparison of calcium and ultrasonic treatment on fruit firmness, pectin composition and cell wall-related enzymes of postharvest apricot during storage

This study was conducted to examine the effects of calcium treatment (2%, 20 min) and ultrasonic treatment (400 W, 20 min) on postharvest apricot fruit during storage. The results showed that after calcium and ultrasonic treatment, compared with the control, the firmness of apricot fruit increased by 41.53% and 3.83% at 16 d, but juice yield and water-soluble pectin (WSP) content decreased by 8.26% and 3.55%, 28.57% and 4.08%, respectively. Both calcium and ultrasonic treatment were more effective in reducing polygalacturonase (PG), β-Galactosidase (β-Gal), pectin methylesterase (PME), polyphenol oxidase (PPO) and peroxidase (POD) activity. Moreover, fruit firmness was significantly negatively correlated with juice yield, WSP and PPO, and positively correlated with PG and β-Gal, PPO and POD. In contrast, calcium treatment was more effective than ultrasonic treatment in delaying postharvest softening of apricot.

Impact of sanitizer solutions on microbial reduction and quality of fresh-cut pennywort (Centella asiatica) leaves

Fresh pennywort (Centella asiatica) is usually eaten raw as 'ulam' or salad-like lettuce. Unfortunately, the fresh pennywort has the potential to cause foodborne outbreaks due to pathogens present on the surface and between the leaves, as washing the pennywort using tap water alone cannot guarantee that the pathogens are eliminated. Thus, the efficacies of several sanitizing solutions, i.e., sodium chloride, sodium hypochlorite, acetic acid, acidic electrolyzed water (acidic EW), alkaline electrolyzed water (alkaline EW), and a combination of acidic EW and alkaline EW (acidic-alkaline EW), were evaluated for their potential applications as washing solutions for pennywort. Washing using acidic EW alone or in combination with alkaline EW (two-step washing) reduced the microbial count. In sensory evaluation, all sanitizer solutions were accepted by the panellists with a score greater than 5, except those washing with acetic acid. Overall, the use of acidic EW, either alone or in combination with alkaline EW, was the best treatment to decontaminate microbes while maintaining the physicochemical and sensory properties of pennywort leaves.

Effects of ultrasonic treatment on color, carotenoid content, enzyme activity, rheological properties, and microstructure of pumpkin juice during storage

Freshly squeezed pumpkin juice (Cucurbita moschata D.) was sonicated at various power levels at a constant frequency of 25 kHz and a treatment time of 10 min. Samples were stored in the dark for 0, 4, 8, and 12 days at 4 °C and were subsequently analyzed. The combined effects of power level and storage period on color parameters, carotenoid content, particle size distribution, cloud value, rheological characteristics, and microstructure were investigated. The results showed ultrasonic-treated samples had little effect on carotenoid content, cloud value, particle size distribution, and polydispersity during storage compared to those of the untreated samples. The L^⁎, a^⁎, b^⁎, and C* values decreased significantly during 8-12 days of storage, resulting in a significant increase in ΔE, especially 400 W/10 min-treated samples. Meanwhile, the enzyme activity and rheological properties increased significantly on storage days 8-12. However, the microstructure of all samples did not change significantly during storage. Based on these results, during the storage period, the physical and chemical properties of 400 W/10 min-ultrasonic treated pumpkin juice were retained more than those in the untreated pumpkin juice. Therefore, ultrasonic treatment has broad application prospects in preserving bioactive substances and physicochemical properties and improving the storage life of fresh pumpkin juice.

What Do Consumers Think about Foods Processed by Ultraviolet Radiation and Ultrasound?

This study aimed to investigate Brazilian consumers’ perception concerning foods processed by ultraviolet (UV) radiation and ultrasound (US) and define consumer segments considering their socioeconomic characteristics and eating habits towards industrialized products through free word association tasks answered by 1004 participants via an online platform. UV- and US-treated foods were more frequently related to unfamiliar words/terms (21.51 and 36.95%) and negative associations (36.25 and 26.70%) than positive ones (29.89 and 24.20%), respectively. Unfamiliarity and health risk concerns were more reported for US-treated foods by women aged 18–25 and ≥46 with low income, and low and frequent industrialized products consumption, as well as for UV-treated foods by consumers ≤35 years old with low and medium income, and low and frequent industrialized products consumption. This indicates that more clear and trustworthy information is needed before introducing these products in the Brazilian market, mainly for potential target consumer groups identified in this study.

Comparative analysis of antibrowning agents, hot water and high-intensity ultrasound treatments to maintain the quality of fresh-cut mangoes

The effect of high-intensity ultrasound (HIU), antibrowning agents (C₆H₈0₆ & CaCl₂), and hot water bath (65 °C) treatments on the prevention of enzymatic browning and 2 weeks shelf-life study of fresh-cut mango fruit slices were evaluated. Results showed that HIU treated mangoes have the lowest PPO activity ranging from 76.17 U/mL to 134.12 U/mL, while improved sensorial properties including decay and off-odor, and enhanced bioactive compounds (ascorbic acid, antioxidant capacity and total phenolics) during storage (4 °C). It is stated that HIU treatment as a promising alternative to replace chemical and/or physical methods to prolong the shelf-life and pursue the quality properties in mango fruit during cold storage.

Food preservation techniques and nanotechnology for increased shelf life of fruits, vegetables, beverages and spices: a review

Food wastage is a major issue impacting public health, the environment and the economy in the context of rising population and decreasing natural resources. Wastage occurs at all stages from harvesting to the consumer, calling for advanced techniques of food preservation. Wastage is mainly due to presence of moisture and microbial organisms present in food. Microbes can be killed or deactivated, and cross-contamination by microbes such as the coronavirus disease 2019 (COVID-19) should be avoided. Moisture removal may not be feasible in all cases. Preservation methods include thermal, electrical, chemical and radiation techniques. Here, we review the advanced food preservation techniques, with focus on fruits, vegetables, beverages and spices. We emphasize electrothermal, freezing and pulse electric field methods because they allow both pathogen reduction and improvement of nutritional and physicochemical properties. Ultrasound technology and ozone treatment are suitable to preserve heat sensitive foods. Finally, nanotechnology in food preservation is discussed.