The effect of amount of manure (animal dung) on the texture of muskmelons (Cucumis melo L.) has been studied. Melons were grown in a greenhouse with 20 and 50 t·ha-1 of manure. Melons were harvested four times at 4-day intervals and kept at ambient conditions for about 8-12 days. Texture was determined by using “Firm Tester” that employs acoustic technology and to provide a firmness index expressed as transmission velocity [meters per second (m/s)]. At the time of the first, second, third and fourth harvest the fruit grown with 20 t·ha-1 manure gave mean transmission velocities of 54.5 ± 2.5, 55.2 ± 5.7, 49.6 ± 4.8, and 46.8 ± 9.4 m/s, respectively. Linear regression equations for fruit grown with 20 t·ha-1 manure showed that the fruit from the first harvest took 10 days to reach 40 m/s, while fruit from the second, third and fourth harvest took 11, 9.5, and 4 days, respectively, to reach this index. The corresponding values for fruit grown in 50 t·ha-1 of manure were 7.5, 10, 5.5 and 4.5 days, those from the second harvest gave the best keeping quality. The firmness index of melon grown in 20 t·ha-1 of manure was greater than that grown in 50 t·ha-1 manure. Higher soil NO3-N contents were associated with softer melons. The correlation between panelist scores for texture and the firmness index was 0.907. Both °Brix and panelist scores for sweetness indicated that manure did not affect the sweetness of melon. The digital firmness tester could detect the effect of manure on the texture of the melons, and could be used to determine the appropriate time of harvest for each and every individual melon.
A nondestructive, acoustic method was applied to evaluate firmness of nectarines (Prunus persica Batch.), apricots (Prunus mume Sieb. et Succ.), plums (Prunus salicina Lindl.), and tomatoes (Lycopersicon esculentum Mill. `Beiju'). Sound with frequencies from 200 to 2000 Hz, generated by a miniature speaker attached to the fruit surface, was received by a small microphone attached to the opposite side. The signal was monitored by an oscilloscope. Sound frequency did not change during propagation in the fruit. However, as the microphone was moved along the circumference of the fruit, a phase shift in the received signal was observed. When the distance the microphone was displaced along the surface of the fruit corresponded to a shift of exactly one wavelength, the sound wavelength propagated within the fruit could be determined. The number of sound waves within the fruit over half its circumference was calculated as a function of this distance. Mature fruit propagated shorter wavelengths and consequently more sound waves than immature fruit, indicating that the sound velocity in the mature fruit was lower than in immature fruit. This relatively simple method for measuring lower frequency suggests that the sound velocity propagated through fruit can be determined without measuring the absolute velocity.
Elasticity, internal C2H4, CO2, and O2, diameter, firmness, and starch index were determined for ripening `McIntosh', `Red Delicious' and `Golden Delicious' apple fruit. Elasticity, measured by the acoustic impulse response of the apple, has previously been found to correlate with fruit firmness after harvest (Armstrong and Brown, 1992) and was studied as a possible index of apple harvest maturity because it is a rapid, non-destructive measurement that could be adapted for field use. However, elasticity did not correlate with firmness or other maturity parameters for fruit attached to the tree. Fruit temperature influenced internal gas levels, probably due to its effect on metabolic activity. An increase in the temperature-compensated internal CO2 level occurred for fruit having an elevated internal C2H4 concentration (> 0.02 μl/L), which suggested that the climacteric respiratory increase associated with ripening occurred while fruit were attached to the tree.
). Previous studies have reported that when evaluating flesh firmness using acoustic methods, measurement values are influenced by factors such as measurement position and fruit shape ( Al-Haq and Sugiyama, 2004 ; Shmulevich et al., 2003 ). Because mango
( Magness and Taylor, 1925 ; Molina-Delgado et al., 2009 ) or a non-destructive acoustic resonance technology ( De Baerdemaeker, 1988 ). Data from such tests have been shown to correlate well with sensory firmness, hardness, or fruit maturity; however, very
unfavorable weather conditions (e.g., decrease in pollen viability and/or pollinator activity) ( Pisanty et al., 2016 ). Additionally, cytokinins known to promote cell division can affect watermelon flesh firmness and cell density ( Soteriou et al., 2017 ) and
encompasses mechanical (e.g., firmness and hardness) and acoustic (e.g., crispness) characteristics. These characteristics can be measured instrumentally using, commonly, a penetrometer (via puncture tests), routine sensory assessment (necessary throughput of
was calibrated with external ethylene standards (certified as β-standard by B.O.C. Gases) with 101 μL·L −1 and 11.2 μL·L −1 standards used in 2003 and 2004, respectively. Quality assessment. In 2004 only, an acoustic firmness measurement of
technical aids during harvest for rapid, accurate selection of watermelon with acceptable SS content and color. Acoustic applications have been tried, but like with NIR, success is highly dependent on the cultivar and type (round versus oblong, seeded versus
as g⋅kg −1 . Texture attributes. Texture properties were evaluated by a texture profile analysis (TPA) test. Firmness, cohesiveness, springiness, and chewiness were determined by using a texture analyzer (CT3; Brookfield, Middleboro, MA, USA