Mitigating effect of relative humidity (RH) on 2-furoylmethyl-Amino acid formation

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Different ultrasound frequencies as pretreatments with different infrared drying temperatures were tested for drying of sweet potatoes to study the drying kinetics, mathematical modeling, energy activation, and thermodynamic properties of dried sweet potatoes. The treated samples showed a significant reduction in drying time by 110 to 60 min as compared to the control ones. Hii model, Page model, and Silva models found satisfactorily described the drying kinetics among 13 different tested mathematical models. The effective diffusion varied from 1.01 × 10 −06 to 9.21 × 10 −06 , while the lowest activation energy recorded as 24.69 kJ/mol in samples pretreated with 40 kHz. The enthalpy and Gibbs free energy decreased with the increase in drying temperature while entropy decreased and obtained as negative during drying. In addition, the moderate ultrasound frequency of 40 kHz positively and significantly (p < 0.05) influenced the surface color, enzyme inactivation, enzymatic browning, and microstructure of dried sweet potatoes. Practical applicationsThis study investigated the impact of sequential ultrasound (US) frequencies and infrared (IR) temperatures. The study provides significant evidence that the US in combination with IR not only reduces drying time but also improve the quality of the dry product on moderate US frequency. Higher US frequency (60 kHz) at higher temperature did not significantly improve the drying time but also showed big pores in SEM analysis.

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Multi‐frequency ultrasound and sequential infrared drying on drying kinetics, thermodynamic properties, and quality assessment of sweet potatoes

Rashid

Jatoi

et al. 2019

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“…From Figure 4, the various identifiable deformation and stretching (peaks) at various regions were correlated to a known functional group. For example, according to Amanor‐Atiemoh et al (2019), Tahir et al (2017) and Sarpong et al (2019), the deformations (peaks) observed in the region of 2,800–3,000 cm −1 are ascribed to NH 3, OH, and CH; by virtue of the vibrational consequence of free amino acids, phenolics, carboxylic acids, and carbohydrates. Deformation of CO observed in the peak region 2,250–2,400 cm −1 is as a result of intensity of heat (Witkowski & Koniorczyk, 2018).…”

Section: Resultsmentioning

confidence: 98%

“…Functional groups present in the sample were determined using the FT‐IR spectroscopy. The experiment was performed according to method by Amanor‐Atiemoh et al (2019) and Sarpong et al (2019). FT‐IR (Nicolet iS50 FT‐IR Spectrometer, Thermo Scientific) was employed to determine FTIR spectroscopy of the treated and untreated (control) sample.…”

Section: Methodsmentioning

confidence: 99%

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

Zhou

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.

“…To determine functional groups present, Fourier transform infrared (FT‐IR) spectroscopy was employed. The experiment was conducted according to method by (Sarpong et al, ) with minor modification. The Thermo Scientific Nicolet iS50 FT‐IR Spectrometer (Thermo Fisher) was used to ascertain the FT‐IR spectra of sample equipped with diamond single reflection Attenuated Total Reflectance as well as zine selenide crystal.…”

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

Zhou

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.