Drying kinetics, antioxidants, and physicochemical properties of litchi fruits by ultrasound‐assisted hot air‐drying

Cao, Xiaohuang; Islam, Md. Nahidul; Zhong, Saiyi; Pan, Xinxiang; Song, Mubo; Shang, Feifei; Nie, Hui; Xu, Wanxiu; Duan, Zhenhua

doi:10.1111/jfbc.13073

Cited by 23 publications

(14 citation statements)

References 33 publications

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“…Dried samples (2-5 g) were picked for moisture determination using a hot air oven at 105 • C until constant weight, as described in the modified methods [24,25]. Protein was determined by the Kjeldahl method [23].…”

Section: Proximate Composition Analysesmentioning

confidence: 99%

“…An evaluation of samples texture was achieved using a TX-XT Express texture analyser (Stable MicroSystems, Vienna Court, Lammas Road, Godalming GU7 1YL, United Kingdom) as described by Cao, Islam, Zhong, Pan, Song, Shang, Nie, Xu, and Duan [24]. The test program was a penetration of compressibility.…”

Section: Determination Of Texturementioning

confidence: 99%

“…Then, 20% sulfuric acid solution (10 mL) and 1% starch solution (1 mL) were supplemented. The sample was titrated with a dropping of 0.01 M of I 2 solution until it obtained a blue colour, which did not fade for 15 s. The consumed volume of I 2 solution was used for assessing the vitamin C content (mg/kg of vitamin C, d.b(dried basis)) [24]. The method was verified using standard vitamin C.…”

Section: Determination Of Vitamin Cmentioning

confidence: 99%

“…Calibration curves were depicted with six points by using a standard substance of gallic acid of 1 mg/L, 2 mg/L, 4 mg/mL, 6 mg/L, 8 mg/L, and 10 mg/L. The total phenolic compounds were calculated as mg/kg of dry matter and expressed as gallic acid equivalent [24].…”

Section: Total Phenolic Compoundsmentioning

confidence: 99%

“…Using IOH, the IAD of litchi fruits is expected further to raise the retention of vitamin C and phenolics and to lower energy consumption. Far fewer reports can be found regarding IOH and related to IAD, and even less reports have attempted to assess the flavours and odours of dried litchi [23][24][25][26][27][28][29][30][31][32][33]. Therefore, an attempt has been taken to improve the colours, tastes, and odours and decrease the loss of vitamin C and phenolics during drying as well as lower energy consumption.In this study, new knowledge was provided about IOH affecting the antioxidant substances, energy consumption, colours, tastes, odours, and water dynamics of litchi fruits.…”

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confidence: 99%

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Energy Consumption, Colour, Texture, Antioxidants, Odours, and Taste Qualities of Litchi Fruit Dried by Intermittent Ohmic Heating

Cao

Islam

et al. 2020

Foods

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To reduce the cost of dried litchi fruit, the processing characteristics and physicochemical properties of litchi were investigated using drying by intermittent ohmic heating (IOH) (intermittent air drying (IAD)) generated by BaTiO 3 resistance. Litchi fruit pulp were dried at 70 • C with an air velocity of 1.8 m/s; the drying intermittent profiles were as follows: (1) 20 min drying-on and 5 min drying-off; (2) 20 min drying-on and 10 min drying-off; and (3) 20 min drying-on and 15 min drying-off, which correspond to pulse ratios (PRs) of 1.2, 1.5, and 1.8, respectively. After drying, the water content, energy consumption, vitamin C content, total phenolic content, colour, taste, and odour qualities were assessed. The results suggested that IOH drying requires lower energy consumption and yields higher quality products. The energy consumption of intermittent air drying ranged from 341 kJ·g −1 to 427 kJ·g −1 . The IAD of 1.2 and 1.5 PR reduced the browning of litchi fruits and gained better product quality. The major components of odour and tastes were explored in dried litchi. The rising PR of IAD enabled a lower retention of methane and sulphur-organic aroma and a higher assessing value of bitterness taste. This study revealed that BaTiO 3 is suitable for IOH drying and it resulted in more merits of dried litchi fruit.Litchi fruits are mostly processed by air drying with a simple technology of conventional ohmic heating of a chromel-filament [6]. However, conventional ohmic heating (air drying) is shown to have low energy efficiency, take longer, and produce low product quality [11]. Additionally, the continuous ohmic resistant heat of air drying can degrade the antioxidant compounds, colour, flavour, and sensory qualities of litchi fruits [12]. Therefore, it is of great significance to obtain dried product with better colour, odour, nutrition, and low energy consumption in the drying of litchi fruit. However, Song C.F. et al. [6] assessed the sensory qualities of dried litchi fruits and found that the acceptance of dried product is not affected by various drying methods. Intermittent air drying (IAD) is known as an outstanding technique in food drying [12][13][14][15][16]. Intermittent air drying confirmed that IAD decreases the operation cost and increases yields of high-quality fruits and vegetables [13][14][15]. IAD allowed the easy movement of moisture from the interior to the surface of material spontaneously by temperature gradient [15]. Moreover, a temperature drop during the tempering period is found to reduce the nutrient degradation [16]. It is reported that intermittent dehydration decreased energy consumption in onion by 12% and obtained 17% energy savings in apple drying [17,18]. The ohmic heating of BaTiO3 resistance provides more merits of safety, clarity, and moderation with its resistance of positive temperature coefficient [18][19][20][21][22]. Using IOH, the IAD of litchi fruits is expected further to raise the retention of vitamin C and phenolics and to lower energy consumption. Far fewer re...

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Section: Proximate Composition Analysesmentioning

confidence: 99%

Section: Determination Of Texturementioning

confidence: 99%

Section: Determination Of Vitamin Cmentioning

confidence: 99%

Section: Total Phenolic Compoundsmentioning

confidence: 99%