Infrared Drying as a Quick Preparation Method for Dried Tangerine Peel

Abstract

To establish the most convenient and effective method to dry tangerine peels, different methods (sun drying, hot-air drying, freeze drying, vacuum drying, and medium- and short-wave infrared drying) were exploited. Our results indicated that medium- and short-wave infrared drying was the best method to preserve nutraceutical components; for example, vitamin C was raised to 6.77 mg/g (D.W.) from 3.39 mg/g (sun drying). Moreover, the drying time can be shortened above 96% compared with sun drying. Importantly, the efficiency of DPPH radical scavenging was enhanced from 26.66% to 55.92%. These findings would provide a reliable and time-saving methodology to produce high-quality dried tangerine peels.

Tangerine, banana and pomegranate peels valorisation for sustainable environment: A review

“…The data of the Food and Agriculture Organization of the United Nations have shown that China is the world's largest producer of tangerine with a surface area of 1.34 million ha and a production of 19.21 million metric tons in 2018 [ 11 ]. This fruit is largely consumed fresh for its distinctive bittersweet characteristic flavour and its high nutritional contents [ 38 , 39 ]. Furthermore, about 28 % of total tangerine fruit is processed to produce juice and other commercial products [ 40 ].…”

“…The tangerine is one of the most popular and most accepted fruits worldwide, this fruit is composed of the peel, arils and seeds ( Table 1 ) . Tangerine is very rich in nutritional content, especially fibres, carbohydrates, lipids, proteins, oligo-elements such as calcium (Ca), iron (Fe), manganese (Mn), phosphorus (P), potassium (K), copper (Cu), sodium (Na) and zinc (Zn), fatty acids [ 6 , 39 , 72 ] and also contains bioactive compounds, such as antioxidants, flavonoids, vitamins (Vitamins C, A, E, K, B 1 , B 2 , B 3 , B 5 ) and other phenolic acids [ 73 ].…”

“… Notes : GAE: Gallic acid equivalents. Source: adapted data; a = 1 [ 135 ], 2 [ 292 ], 3 [ 39 ], 4 [ 32 ], 6 [ 293 ], 5 [ 72 ], 7 [ 18 ], 8 [ 176 ], 9 [ 294 ], 10 [ 295 ]. b = 1 [ 45 ], 2 [ 80 ], 3 [ 296 ], 4 [ 297 ], 5 [ 298 ], 6 [ 79 ], 7 [ 8 ], 8 [ 299 ], 9 [ 300 ].…”

Flavor Characteristics of Ganpu Tea Formed During the Sun-Drying Processing and Its Antidepressant-Like Effects

“…Moreover, isoleucine 7, threonine (8), arginine (9), and glutamine (10), labeled with asterisks in Figure 2A, were newly generated amino acids during the full sun-drying processing, as they were identified exclusively in Ganpu tea, but not in Pu-erh raw tea or mandarin peel. In addition to the common tea catechins, such as GC 11 (26) were newly generated during the sun-drying process, as they were discovered exclusively in Ganpu tea ( Figure 2B).…”

“…To date, numerous methods including hot-air drying, freeze drying, vacuum drying, and infrared drying, have been applied to dry agricultural products (7)(8)(9). Hot-air drying is the method most commonly used to dry Ganpu tea.…”