Immaturity has been linked also to a poor yield of vanillin in the cured beans (Saltron et al., 2002, 2003). Cured beans contain about 2.5% of vanillin when properly prepared. Molds attack the bean from the fruit base, where the vanillin concentration is the least (Bourriquet, 1954). It should be stressed that vanillin has been reported to have antimicrobial properties against different food-related microorganisms (Nakazawa et al., 1982) and some pathogenic, indicator, or spoilage microorganisms: Escherichia coli, Enterobacter aerogenes, Pseudomonas aeruginosa, Salmonella enterica, Candida albicans, Lactobacillus casei, Penicillium expansum, and Saccharomyces cerevisiae (Rupasinghe et al., 2006). In vitro studies have shown that vanillin is effective in molds growth inhibition. The addition of 1000 ppm of natural vanillin for instance inhibited Aspergillus ochraceus growth for more than two months at 25°C, while growth of A. flavus, A. niger, and Aspergillus parasiticus was inhibited by 1500 ppm (Lopez-Malo et al., 1995, 1997). Vanillin has been proposed by these authors for hurdle technology in combination with other antimicrobial factors such as reduced pH and aw to prevent mold spoilage in fruit purées. Another study using different food-spoilage molds and yeasts have suggested that the aldehyde moiety plays a key role in the antifungal activity of vanillin (Fitzgerald et al., 2005). These authors (Fitzgerald et al., 2004) have also investigated the mode of action of vanillin against Escherichia coli, Lactobacillus plantarum, and Listeria innocua. The antimicrobial activity of vanillin was dependent on the time of exposure, concentration, and the target organism. The in vitro minimum inhibitory concentrations of vanillin were 15, 75, and 35 mmol/L for the three tested strains. This inhibitory action of vanillin was found bacteriostatic rather than bactericidal for all. This study demonstrated that the vanillin disturbs the integrity of the cytoplasmic membrane, leading to the loss of ion gradients, pH homeostasis, and inhibition of respiratory activity of the tested bacteria.
The potential hazards for cured vanilla beans can thus be categorized as follows:
• Microbial spoilage due to bacterial fermentation or molds development
• Contaminations from microbial toxins (mycotoxins from molds)
• Bacterial contaminations related to poor hygienic conditions
To prevent these microbial hazards of cured vanilla beans, the relevant factors that should be controlled are the maturity of the green beans at harvest, the aw of the processed beans, and the overall postharvest hygienic conditions. To preserve the quality of the beans during the storage that could last several months or up to one year, other parameters such as temperature, humidity, gas composition, and type of packaging should also be taken into consideration.
Microbial Hazards Management and Control
Control measures aim to prevent, eliminate, or reduce food safety hazards to a tolerable level by either controlling initial levels of a hazardous agent, or preventing an increase in its levels, or reducing its levels. An important role of Hazard Analysis Critical Control Point (HACCP) is to help the food producer and processor build safety into processes through identification of key or critical control measures that prevent, eliminate, or reduce hazards to acceptable levels.
The control of microbiological hazards of cured vanilla beans is particularly dependent on effective drying and the subsequent prevention of postprocess contamination and/or growth. The most effective microbial control measure in vanilla beans processing is to dry the commodity such that aw is very low to support the microbial development, and in particular, the mold growth and/or prevent myco-toxin production from toxinogenic species. aw is a measure of the water that is available to microorganisms. To prevent the growth of most molds, aw needs to be ≤0.70. Each toxigenic mold has its own minimum aw for growth and mycotoxin production and these translate into moisture contents for each commodity. These moisture contents are termed “safe” and would be the critical limit for the control measure. Most spoilage bacteria cannot grow at an aw ≤ 0.91. Staphylococcus aureus has, however, been found to grow at aw as low as 0.84. Since molds are able to grow over a wide range of pH values, moisture conditions, and wider temperature range than bacteria, they are more susceptible for contaminating vanilla beans. A critical control point could be placed at the end of the drying process and one critical limit would be the water content or aw of the beans, which would be easy to monitor in an HACCP system.
Poor hygienic conditions are a major source of contamination of the beans during the whole process. Since the majority of microorganisms are located onto the surface of the beans, the education of handlers is a priority. Hands as well as contaminated gloves and blankets can serve as vectors for the transmission of microorganisms. As reported in the literature, the hands of food workers are of major importance in the transfer of contaminants from person to person, from person to surfaces or vice versa, and from person to food (Guzewich and Ross, 1999). Good housekeeping procedures are necessary to minimize the levels of insects and fungi in storage facilities. Moldy beans should be discarded immediately because they lead to off-odors and lead to cross-contaminations between different lots of the vanilla beans.
From this point of view, the HACCP system is a widely recognized food safety management. It is a systematic approach in identifying, evaluating, and controlling food safety hazards. It is based on a preventive approach from the primary production till the end product sold on the market rather than relying solely on conventional inspections by regulatory agencies. Once an HACCP plan has been developed and introduced into a food operation it must be maintained on a continuous basis. The seven principles are: (1) identifying any hazards that must be prevented, eliminated, or reduced to acceptable levels; (2) identifying the critical control points (CCPs) at the step(s) at which control is essential to prevent or eliminate a hazard or to reduce it to acceptable levels; (3) establishing critical limits at CCPs, which separate acceptability from unacceptability for the prevention, elimination, or reduction of identified hazards; (4) establishing and implementing effective monitoring procedures at CCPs; (5) establishing corrective actions when monitoring indicates that a CCP is not under control; (6) establishing procedures, which shall be carried out regularly, to verify that the measures outlined are working effectively; and (7) establishing documents and records commensurate with the nature and size of the food businessto demonstrate the effective application of the measures outlined. CCP, as defined in the Food Code, means a point at which loss of control may result in an unacceptable health risk (FDA, 2009). These principles have international acceptance and their application have been described by the food hygiene code of the Codex Alimentarius Commission (CAC, 2003), the National Advisory Committee on Microbiological Criteria for Foods (NACMCF, 1992), the ISO 22000 (ISO, 2005), the Food Code of the Food and Drug Administration (FDA, 2009), and the European regulation No 852/2004 (JO, 2004). Since 2006, this new European regulation on the hygiene of foodstuffs has been applied and it is also applicable to foreign operators who produce export food to the European Union. The new hygiene rules take particular account of the following principles: