The effect of killing conditions on the structural changes in vanilla (Vanilla planifolia, Andrews) pods during the curing process

Abstract

The effect of seven methods of killing vanilla (Vanilla planifolia, Andrews) pods on disassembly of the cell wall was studied. The following methods of plant killing were considered in this study: pod immersions in hot water under three conditions (65°C for 3 min, 70°C for 2 min, 80°C for 10 s each of three times in 30 s intervals), pod immersions in 1% NaOH at 22°C or 65°C for 3 min, pod immersions in 95% ethanol at 22°C for 60 min, and freezing at )10°C for 24 h. Two procedures of vanilla pod killing, pod freezing at )10°C for 24 h or pod immersions in hot water at 80°C for 10 s each of three times in 30 s intervals, provoked the deepest and fastest disassembly of the cell wall structure and the successive cell content blending of the vanilla pod during the 8 days after curing.

Microstructure of Mature Green Mexican Vanilla PodsVanilla planifolia(Andrews) by Microscopy Techniques and Digital Image Analysis

“…The cells forming the vascular bundles were polyhedral, polydispersed (different sizes), thick-walled cells, as observed under light and environmental scanning electron microscopes (Figures 2A and 2B); The DIA applied to the images captured by light microscopy revealed the following morphometric parameters of this structural region: 3061 ± 11.64 µm 2 A, 246 ± 2.94 µm P, 0.69 ± 0.10 SF, and 78 ± 1.36 µm FD. With respect to the arrangement of the 18 VB in the parenchyma (Figure 1B), the number of bundles identified was similar to that reported by other authors (8,21) for green mature pods of V. planifolia cultivated in Papantla de Olarte, Veracruz, Mexico and the Democratic Republic of Madagascar, respectively. As illustrated in Figure 2, by moving to the inner part of the pod, the EN was observed to be constituted by two strings of cubic cells of smaller size than those found for the EP and the mesocarp (Figures 2A and 2D); their morphometric parameters were: 640 ± 4.05 µm 2 A, 100 ± 1.34 µm P, 0.80 ± 0.10 SF, and 41 ± 0.81 µm FD; the thickness found by DIA was 0.07 mm.…”

“…The "curing" process of pods lasts three months, although it could take up to six months depending on the source region and country; the procedure differs for every part of the world and also between authors (7). Anatomical works have been reported and analysed by using different microscopic techniques: optical (8), confocal laser (9), scanning and transmission electron (10). In such studies, the histological characterization of green mature vanilla pods has been performed as a general description of the cells from EP, OM, MM, EN and TC, as well as of P and SE.…”

The effect of thermal treatment on β‐glucosidase inactivation in vanilla bean (Vanilla planifolia Andrews)

“…In Mexico, the most practical method of vanilla bean killing is still hot water treatment. It consists of keeping mature pods packed in a blanket of 30–40 pieces and submerging them in hot water at different time and temperature: at 60 °C for 3 min, at 70 °C for 90 s, or three repeated submersions at 80 °C for 10 s each (Mariezcurrena et al ., 2008). Each producer is convinced that his conditions represent the best protocol.…”

Involvement of Colonizing Bacillus Isolates in Glucovanillin Hydrolysis during the Curing of Vanilla planifolia Andrews

“…The vanilla beans are then subjected to a process that involves periodic sweating and drying. During the remaining part of the day, the vanilla beans are allowed to acclimate on wooden racks in a well-ventilated room and are then stored in small bundles in plastic vacuum bags at room temperature (4,5).…”