Little known facts: Pistacios can self-ignite! Exert from the TIS: RF Self-heating / Spontaneous combustion Oil content: 45 - 54% [1] 55% [2] Because of their tendency to self-heating, pistachio nuts may behave like substances from Class 4.2 of the IMDG Code. Excessive stack pressure results in self-heating. Oils which have accumulated in the jute packaging fabric encourage this behavior. Pistachio nuts, especially pistachio kernels, should not be stowed together with fibers/fibrous materials as oil-soaked fibers may promote self-heating/spontaneous combustion of the cargo. As a basic principle, a high oil content (especially in pistachio kernels) encourages the tendency to self-heating. Fat decomposition in pistachio nuts leads to the risk of self-heating and, ultimately, to a cargo fire. Fat decomposition may proceed as follows: by hydrolytic/enzymatic fat cleavage or by oxidative fat cleavage Hydrolytic/enzymatic fat cleavage: If the critical water content of the pistachio nuts is exceeded, this promotes hydrolytic/enzymatic fat cleavage. Fat-cleaving enzymes are activated by the elevated water content. The additional action of light and heat may accelerate this process. Free fatty acids sometimes have an unpleasant odor and taste. In the event of extended storage or improper cargo care, these cause the cargo to become rancid. The free fatty acids formed are consumed by respiration processes in the pistachio nuts to form carbon dioxide and water, a process which is associated with considerable evolution of heat. Self-heating of pistachio nuts is an extremely vigorous process, as the consumption of fatty acids by respiration processes is associated with a considerably greater evolution of heat than is the case with the respiration equation for carbohydrates. Here too, as with cereals, the spoilage process proceeds in a type of chain reaction, because heat and water are formed by the fatty acids consumed by respiration, which in turn contribute to an intensification of the process. The self-heating of pistachio nuts requires only a small seat of moisture, so that within just a few hours heating may occur at moist points for which weeks or months would be required in goods dry on shipment. Fresh pistachio nuts with a high water content tend in particular towards rapid self-heating and may also ignite. Self-heating of pistachio nuts leads not only to a reduction in the utility value of this product (rancid odor and taste) but also has a qualitative and quantitative effect on oil yield. The color and bleachability of the oils are also negatively affected. The oil obtained complicates refining of the crude oils in subsequent processing, because a higher free fatty acid content makes decolorization substantially more difficult. Hydrolytic/enzymatic fat cleavage and respiration may be limited by low temperatures; however, this may only be affected to a limited degree during transport. It is therefore important to ensure storage stability by complying with the limit values for the water content of the goods. Oxidative fat cleavage: Food components frequently react with atmospheric oxygen in spoilage processes. Atmospheric oxygen may enter into an addition reaction with unsaturated fatty acids through the simultaneous assistance of light, heat and certain fat companion substances, and possibly also traces of heavy metals. Rancidity caused by oxidative fat cleavage is particularly noticeable in the case of shelled pistachio nuts, because the shelling process results to a certain degree in exposure to atmospheric oxygen or to the steel parts of the ship or the container walls, if not carefully covered. It is therefore absolutely essential to store pistachio nuts in the dark and to protect them from oxygen and metal parts, since otherwise they become brown-colored and develop a rancid odor and taste.
Posted on: Mon, 22 Jul 2013 08:43:56 +0000
Trending Topics
Recently Viewed Topics
© 2015