title: Keywords - Namangan Institute of Engineering and Technology nammti uz
text: Namangan Institute of Engineering and Technology
  nammti.uz
  10.25.2023
  Pg.201
  does not present resistance to the measured electrical current. Based on the frequency dependency
  of the conductivity of intact and permeabilized tissues, a cell disintegration index Z was calculated
  by the following equation:
  where K
  i
  , K’
  i
  are the electrical conductivities of untreated and treated material, respectively,
  at a low-frequency field K
  b
  , K’
  b
  are the electrical conductivities of untreated and treated material,
  respectively, at a high frequency field. This index characterizes the proportion of permeabilized cell
  in a material. For intact tissues, Z ¼ 0; for a tissue where all cells are permeabilized, Z ¼ 1.
  Whole tomatoes were immersed into the treatment chamber (10 cm x 5 cm x 8 cm) filled with
  tap water. Treatment chambers with different electrode gap widths were used for chopped
  tomatoes (4 cm x 5 cm x 4 cm) and tomato wastes (4 cm x 2.5 cm x 4 cm) without tap water, thus
  PEF treatment was directly applied to the samples. Electrical conductivities for untreated samples
  were calculated prior and immediately after PEF treatment for each condition applied for whole
  tomatoes, chopped tomatoes and tomato wastes. The chamber electrodes in all treatment chamber
  configurations were made of stainless steel. The treatment chamber
  was connected to the
  measuring apparatus as shown in Fig. 1 using crocodile clips. The goal of the apparatus is to measure
  the electrical impedance of the treatment chamber by recording two voltage drops with the
  oscilloscope[2].
  800 g of whole tomatoes were cut in cubes of 1.5
  𝑥
  1.5
  𝑥
  1.5 cm
  3
  dimensions. Juice extraction
  was performed on a lab-scale paddle type extractor (SpremiTO, Tre Spade, Torino, Italy). Tomato
  juice extraction yield was calculated taking into account the mass of the tomatoes (kg) and the
  tomato juice (kg). The extraction yield was expressed in percentage (%) of chopped tomatoes to
  mass of tomato juice from the first juicing step and the overall extraction yield was expressed in
  percentage (%) of chopped tomatoes to mass of overall tomato juice (from the two juicing steps).
  The results obtained in our research show that PEF technology at selected conditions could
  be applied as pretreatment to critical steps in the tomato industry leading to a decreased energy
  consumption, increased productivity and more effective valorization of tomato waste. Generally,
  increasing electric field strength and treatment time increased the cell disintegration index Z and in
  turn improved the peeling process, the juice yield and the extraction of intracellular compounds
  from tomato waste. In the case of peeling, PEF pretreatment performed in mild conditions reduced
  the surface resistance of tomato skin and its adhesiveness to the tomato flesh, leading to reduced
  peeling loss and low energy consumption compared to commercial peeling processes.
  The low
  temperatures associated with PEF treatment led to final peeled tomatoes with well-preserved
  shape and texture, improved quality and functionality because of high lycopene concentration of
  the end product. PEF can easily replace existing conventional peeling processes, leading to reduced
  water and energy requirements. In the case of juicing, PEF pretreatment increases the tomato juice
  yield up to 20% compared to control at the first step of juicing (equal with total juice yield from both
  juicing steps of untreated samples), resulting in increased Bostwick consistency values (>20 cm) of
  the
  final tomato juices, not suitable for the tomato industry. However, the application of PEF
  treatment on the residual tomato wastes at the second step of juicing, led to juice yield increase
  and improved final viscosity, as well as decreased energy consumption and processing time for the
  tomato industry. PEF can be easily integrated into the tomato processing line, before juicing. Taking
  into consideration that PEF has low energy requirements.[3]