Simultaneous multifrequency: A possible alternative to improve the efficacy of ultrasound treatment on cherry tomato during storage

Wahia

et al. 2019

J Food Process Preserv

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Cherry tomato fruits were treated with three dual‐frequency ultrasound (US) at different temperature and time. The three treatment variables, that is, dual‐frequency US, temperature, and time were optimized with the aid of response surface methodology (RSM). About 20/40 kHz, 52°C, and 6 min were the optimum condition obtained for total bacteria count (TBC, 1.08 log cfu/g), firmness (15.90 N), and total phenolic content (TPC, 34.34 mg GAE/100 g). All the linear relations of the treatment variables showed a significantly negative and positive effect on the TBC and TPC, respectively, while positive significant effects were obtained for some of the relations of the firmness. Hence dual‐frequency sonication is effective for microbial safety and maintaining the quality of cherry tomato. Also, RSM was found to be a useful tool in setting and optimizing the variables responsible for sonication treatment. Practical applications Thermosonication (ultrasonication and heat) has been applied toward improving the microbial safety and nutritional quality of vegetables and fruit. However, factors such as power, frequency, time, temperature, etc. determine the efficiency of its operation. Controlling these factors is difficult and therefore requires a robust and efficient optimization tool in determining their effects (individual and interactions) on food during treatment. In this study, response surface methodology provides the solution in settling and optimizing the variables for the sonication treatment. Besides, the remarkable result obtained in this work offers an alternative to the combined use of ultrasound and chemical in food industries.

Section: Resultscontrasting

confidence: 79%

“…The firmness of the sample was determined longitudinally using a texture machine (TAHD; Stable Microsystems, UK). It was equipped with a 2 mm puncture‐probe, 1 mm/s speed, and at a distance of 10 mm (Mustapha et al, ). Results (average) were recorded in Newton (N).…”

Section: Methodsmentioning

confidence: 99%

Combination of thermal and dual‐frequency sonication processes for optimum microbiological and antioxidant properties in cherry tomato

Mustapha

Wahia

et al. 2019

J Food Process Preserv

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“…Antioxidant activities were observed to be correlated with TPC and TFC indicating a relationship between the two and this was confirmed by the correlation analysis shown in Table 2. These were in line with Wang, Dai, et al (2015), Wang, Ma, et al (2015), and Mustapha et al (2019) who reported that phenolic compounds (TPC and TFC) could contribute to antioxidant activities.…”

Section: Resultssupporting

confidence: 87%

Effect of simultaneous dual‐frequency ultrasound aided ethanolic pretreatment on drying kinetics, bioactive compounds, antioxidant activity, and physicochemical properties of apple slices using pulsed vacuum dryer

Amanor‐Atiemoh

J Food Process Engineering

Mujumdar

et al. 2020

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This work aims at investigating effect of different pretreatments and varied temperature on the drying kinetics, bioactive compounds, antioxidant activity, microstructure and functional group of apple slices using pulsed vacuum dryer. Pretreated apple slices (Ethanol, US + W, and US + E) dried at varied temperature (60, 70, and 80°C) were analyzed to determine total phenolic content (TPC), total flavonoid content (TFC), 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH+), 2,2‐azino‐bis‐(3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS+), color, microstructure and FT‐IR spectroscopy. The findings revealed that US + E pretreatment significantly (p < .05) decreased drying time (20–33.33%). Activation energy and moisture effective diffusivity were 17.60–29.86 kJ/mol and 1.52–3.60 × 10−8 m2/s, respectively. Microstructure evaluation showed disruption of cells structure and microchannels formation but was more prominent in US + E pretreatment with noticeable larger pores and several microchannels. US + E pretreatment retained TPC (64.89–75.75 mg/100 g GAE dw), TFC (45.96–56.25 mg/100 g ER dw), DPPH+ (66.85–73.34%) and ABTS+ (62.58–71.17%) than Ethanol, US + W, and control and was further corroborated by the observed peaks as revealed by the FT‐IR spectroscopy. Color (L*, a*, b*, whiteness) was better retained by Ethanol and US + E pretreatments. US + E pretreatment decreased drying time and also preserved bioactive compounds, antioxidant activity and color of apple slices. Practical application Apples are popularly consumed fruits and confer various nutritional and health benefits to humans. Drying is the most common approach for apple processing and shelf life extension. However, drying often leads to a reduction in quality parameters as well as degradation of nutritional components of the apple. Novel pretreatment techniques like ultrasonic aided ethanolic pretreatment preceding to apple drying provides an added advantage over conventional drying methods in that it reduces dehydration time as a result of faster moisture removal, lowers energy consumption, improves process efficiency leading to industrial competiveness and it also preserves the nutritional and sensorial parameters of dried apple slices.

“…Color parameters with reference to lightness ( L *), redness ( a *), and yellowness ( b *), and total color difference (ΔE) were calculated according to Equation (7) using method of (Mustapha et al, ; Ruangchakpet & Sajjaanantakul, ).

normalΔ E = \sqrt{{(L_{o}^{*} - L^{*})}^{2} + {(a_{o}^{*} - a^{*})}^{2} + {(b_{o}^{*} - b^{*})}^{2}}

…”

Section: Methodsmentioning

confidence: 99%

Effect of ultrasound‐ethanol pretreatment on drying kinetics, quality parameters, functional group, and amino acid profile of apple slices using pulsed vacuum drying

Amanor‐Atiemoh

J Food Process Engineering

Taiye

et al. 2019

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The influence of ultrasound-ethanol (US-E) pretreatment durations (10, 20, and 30 min) on apple slices dried with varied temperatures (60, 70, and 80 C) using pulsed vacuum dryer was investigated. The results showed that untreated sample (control) took 375, 325, and 225 min to achieve a constant weight of drying whereas drying time for 30 US-E samples were 275, 225, and 175 min, indicating that 30 US-E reduced the total drying time by 26.66, 30.77, and 22.22% at 60, 70, and 80 C, respectively. Moisture effective diffusivity and activation energy were in the range of 1.98-4.08 × 10 −8 m 2 /s and 12.58-23.43 kJ/mol, respectively. Color (L*, a*, b*) and texture were affected significantly (p < .05) at high temperature and longer US-E.Shorter US-E duration and lower temperature could preserve most functional groups.Also, total free amino acid values were significantly higher at lower temperature and longer US-E pretreatment. Practical applicationsDrying time, nutrient retention, and energy efficiency are at the heart of the food industry. The remarkable reduction obtained in the drying time as well as retaining of some functional groups (nutrients composition) with the use of ultrasound-ethanol as a pretreatment for pulsed vacuum dryer indicates that this technique will serve a great purpose in food processing industries. This in effect will reduce production cost thereby making the business operations of food processors competitive as it provides value proposition to their customers.