Use of a spouted bed to improve the storage stability of wheat germ followed in paper and polyethlyene packages

Abstract

Stabilization of wheat germ by heating in a spouted bed for 180-540 s with air at 140-200 • C was studied. The lipase activity decreased by 6-65%. Wheat germ processed at 200 • C for 360 s was ranked highest in sensory evaluation, described as having 'a golden color' and 'nutty flavor', and its lipoxygenase activity had decreased by 91.2%. This product and raw wheat germ were stored in paper, polyethylene and vacuum-packed polyethylene pouches at 5 • C, room temperature (18-26 • C) and 40 • C, and the moisture contents, water activities, free fatty acid contents and peroxide values were followed for 20 weeks. The increases were faster in paper pouches than in the polyethylene ones; vacuum packaging in polyethylene did not bring about significant improvement. The peroxide values of raw samples exceeded 10 meq O 2 kg −1 oil after 3-23 days while those of the processed samples stored at room temperature or 5 • C were still less than 10 after 20 weeks. The free fatty acid content and peroxide value changes were expressed by zero order kinetics, resulting in similar activation energies for the raw and processed samples.

Modelling Condensation and Simulation for Wheat Germ Drying in Fluidized Bed Dryer

“…Several studies have been conducted to develop the suitable methods for WG stabilization, including short wave infrared radiation [3], gamma irradiation [4], roasting [5][6][7], steaming [8,9], microwave treatment [9][10][11][12], toasting [13,14], temperature controlled water-bath [11,12], sourdough fermentation [14], and fluidization method [9,[15][16][17][18]. However, the processing temperature of these methods was high.…”

Wheat germ thermal treatment in fluidised bed. Experimental study and mathematical modelling of the heat and mass transfer

“…Wheat germ flakes present good potential for fluidisation aimed at stabilising the product due to its non-sticky surface and low density (Gili et al, 2017b). Yöndem-Makascioǧlu et al 2005, studied wheat germ stabilisation employing a special type of fluidised bed, the spouted bed, and reported an increase of the shelf life in wheat germ by a factor of 20. Besides, a golden colour and a nutty flavour was imparted by light roasting.…”

Effect of Loading on Wheat Germ Drying in a Batch Fluidized Bed for Industrial Production

“…The MC of WG should be controlled between 5% and 8%, so as to reduce the enzymatic activity and control the water activity, thereby extending the shelf life [19]. Using fluidized bed drying is one of several methods used to enhance the stabilization of agricultural materials [18][19][20][21][22][23][24]. Fluidization variables affect the quality of the WG product by influencing the moment, heat, and mass transfer, as well as the evaporation rate of MC, in a fluidized bed dryer (FBD).…”

“…These common variables include operation conditions (air velocity, set temperature, heating time, WG loading, FBD type, and FBD size) and surrounding environmental conditions (temperature and relative humidity). The effects of the operation conditions on the drying performance in the FBD have previously been investigated at various set temperatures and heating times [18,21,23].…”

“…The development and optimization of WG drying will not only be invaluable for laboratory studies, but it will also help to determine the operation conditions for industrial-scale production. Fluidized bed drying is an effective drying process, where the WG samples are loaded on a small scale (50-200 g) [22][23][24] or large scale (2 kg) [20,21]. The bed height increases as the grain loading increases.…”