3.1.3. Texture evaluation
In order to compare the effect of different process and formulations on the textural properties of the final product, samples were submitted to compression test. Compression until fracture parameters (force and strain at fracture, as well as initial height and section) of the evaluated systems are shown in Table 3. Fig. 2 displays the stress versus strain representative plots for the studied systems. It can be observed a typical profile of pumpkin tissue submitted to heat treatment. Forces at rupture in the order of 20–40 N were also obtained previously with blanched pumpkin submitted to a subsequent osmotic treatment (de Escalada Pla et al., 2009), while raw pumpkin had presented failure force on their plots and forces at rupture one order higher with respect to cooked pumpkin (de Escalada Pla, Delbon, Rojas, & Gerschenson, 2006). Turgor lost and cell disruption occur due to treatment (Figs. 2 and 3). It can be seen that F1 (starch coating) required a greater force to rupture than F2 (k-carrageenan coating). It must be highlighted that the subsequent air drying process applied on F1 produced shrinkage and consequently a reduction in cylinders’ cross-section. Therefore, highest stress (p < 0.05) was registered for F1 to achieve the breakdown peak. At the same time, this sample (F1) showed the largest degree of strain, then higher firmness (1200 ± 400 Pa) were obtained when compared with F2 (p < 0.05), and a similar trend (non-significant) was observed when compared with control (F3). The increased stress required for breaking the tissue may be due to higher solids concentration by further drying treatment which resulted in retracted tissue which requires higher force to deform the vegetal matrix. In a previous work, authors (de Escalada Pla et al., 2009) stated that WL produced tissue retraction, and so cells became closer, and determining firmness according osmotic equilibrium was reached. The system with k-carrageenan (F2) required the lower stress to achieve tissue breakdown peak when compared with F1. It was also possible to observe the rupture of coating in a first instance and then the tissue fracture with less stress (Fig. 2). This result could be explained considering the generation of a softer product as a result of the higher retention of water in the coating. Both the F2 and the F3 systems required a lower force and strain to get the tissue breakdown (Table 3).
Table 3.
Texture parameters of the pumpkin products obtained by dry infusion: with Fe–tapioca starch coating (F1), with Fe–k-carrageenan coating (F2) and with Fe but without coating (F3, control system).
3.1.3. เนื้อประเมินIn order to compare the effect of different process and formulations on the textural properties of the final product, samples were submitted to compression test. Compression until fracture parameters (force and strain at fracture, as well as initial height and section) of the evaluated systems are shown in Table 3. Fig. 2 displays the stress versus strain representative plots for the studied systems. It can be observed a typical profile of pumpkin tissue submitted to heat treatment. Forces at rupture in the order of 20–40 N were also obtained previously with blanched pumpkin submitted to a subsequent osmotic treatment (de Escalada Pla et al., 2009), while raw pumpkin had presented failure force on their plots and forces at rupture one order higher with respect to cooked pumpkin (de Escalada Pla, Delbon, Rojas, & Gerschenson, 2006). Turgor lost and cell disruption occur due to treatment (Figs. 2 and 3). It can be seen that F1 (starch coating) required a greater force to rupture than F2 (k-carrageenan coating). It must be highlighted that the subsequent air drying process applied on F1 produced shrinkage and consequently a reduction in cylinders’ cross-section. Therefore, highest stress (p < 0.05) was registered for F1 to achieve the breakdown peak. At the same time, this sample (F1) showed the largest degree of strain, then higher firmness (1200 ± 400 Pa) were obtained when compared with F2 (p < 0.05), and a similar trend (non-significant) was observed when compared with control (F3). The increased stress required for breaking the tissue may be due to higher solids concentration by further drying treatment which resulted in retracted tissue which requires higher force to deform the vegetal matrix. In a previous work, authors (de Escalada Pla et al., 2009) stated that WL produced tissue retraction, and so cells became closer, and determining firmness according osmotic equilibrium was reached. The system with k-carrageenan (F2) required the lower stress to achieve tissue breakdown peak when compared with F1. It was also possible to observe the rupture of coating in a first instance and then the tissue fracture with less stress (Fig. 2). This result could be explained considering the generation of a softer product as a result of the higher retention of water in the coating. Both the F2 and the F3 systems required a lower force and strain to get the tissue breakdown (Table 3).ตารางที่ 3พารามิเตอร์ของผลิตภัณฑ์ฟักทองได้ โดยแช่แห้งผิว: ด้วย Fe – มันสำปะหลังแป้งทา Fe – เคคาร์ราจีแนน (F1), เคลือบเคลือบ (F2) และ Fe แต่ ไม่เคลือบ (F3 ระบบควบคุม)
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