FOOD PROCESSING AND ITS IMPACT ON CHIRAL PESTICIDE RESIDUES IN FOOD

The amount of chiral pesticide residues in food products depends on the nature of processing it is subjected to before its consumption. The processing of food can facilitate the degradation and dissipation of some chiral pesticides (Table 9.3) (Lu et al.. 2011; Yang et al., 2020). In some cases, the presence of chiral pesticide residues may cause preferential growth of a certain species of microorganisms, which in turn may enhance processing or work against it by way of reducing the quality of food (Guo et al., 2020). The amount of chiral pesticides in the food consumed by humans is, in most cases, reduced by most of the processing techniques.

Pickling is a food processing technique that is done to preserve vegetables to increase their shelf- life. It can be done using natural fermentation or by the direct addition of salt and vinegar to the food (Yigit and Velioglu, 2019). Many researchers performed some studies to find out the effect of pickling on chiral pesticide residues in food (Table 9.3) (Bian et al., 2020; Guo et al., 2020; Zhao et al., 2019). For instance, Zhao et al. (2019) investigated the effect of the cabbage pickling process on the chiral paclobutrazol pesticide residues. They observed enantioselective dissipation of the enantiomers of paclobutrazol from the cabbage. The dissipation of (R)-paclobutrazol was faster than that of (S)-paclobutrazol. In the same vein. Guo et al. (2020) studied the impact of paclobutrazol residues on cucumber pickling process. They detected that (2/?,3R)-enantiomer of paclobutrazol caused microbial disturbance during the pickling process. Thus, paclobutrazol residues derailed the pickling process by killing some of the microorganisms involved, thereby affecting the quality of

TABLE 9.3

Effects of Food Processing on the Amount of Chiral Pesticide Residues in Food Products

Note: ng - not given.

the pickle. They also observed the occurrence of degradation of the enantiomers of paclobutrazol as well as their interconversion. From their findings, it can be inferred that pickling generally, cause dissipation of some chiral pesticide residues in food resulting in the reduction of their concentration.

Fermentation is another technique that is used during processing of food. It involves the microbial breakdown of food into other substances. It is the main process used in the wine industry during the conversion of grapes into wine. The effect of chiral pesticide residues during wine fermentation have been studied by many researchers (Table 9.3) (Guo et al., 2020; Lu et ah, 2016; Lu et ah, 2011; Yang et ah, 2020). Some chiral pesticide residues undergo degradation during the wine fermentation process. For instance, Yang et ah (2020) investigated the effect of the enantiomers of cyazofa- mid during the wine making process. Their results indicated that the enantiomers of cyazofamid residues in grapes undergo degradation under the fermentation conditions. In another study, Lu et ah (2011) studied the effect of diclofop-methyl during grape fermentation. Their results revealed that diclofop-methyl residues in grapes undergo enantioselective degradation during the fermentation process. They observed that (5)-(-)-diclofop-methyl degraded faster than (R)-(+)-diclofop- methyl under the fermentation conditions. However, the two enantiomers of diclofop-methyl did not undergo interconversion during the fermentation process. Thus, the fermentation process used during winemaking assists to reduce the concentrations of some chiral pesticide residues in grapes, thereby minimizing health risks to the consumers.

Research has shown that other chiral pesticides do not undergo degradation under the fermentation conditions used during winemaking (Table 9.3) (Guo et al., 2020; Lu et al., 2016). The concentrations of their enantiomers remain unchanged throughout the fermentation process. For instance, Lu et al. (2016) performed a study to find out the behavior of benalaxyl pesticides during wine fermentation. Their results revealed that the two enantiomers of benalaxyl were stable under the fermentation conditions and their concentrations remained unchanged until the end of the process. In a similar study, Guo et al. (2020) investigated the effects of the enantiomers of paclobutrazol pesticide during the fermentation process. They observed that the enantiomers of paclobutrazol were stable under the fermentation conditions they used. Their results also revealed that enantiomers of paclobutrazol interfered with the microbial activities during the fermentation process. Thus, these stable enantiomers of some chiral pesticides would remain in the wine until they reach the consumers where they may cause serious health problems.

Household processing plays an integral part in reducing the amount of pesticide residues consumed by humans in food. It involves simple but effective processes such as washing, boiling, soaking, peeling, and drying of food (Table 9.3) (Bian et al., 2020; Luo et al.. 2020). Researches have been conducted to verify the effectiveness of these household processing techniques in reducing the amount of chiral pesticide residues in food. For instance, Luo et al. (2020) investigated the effects of household food processing on the amount of tebufenozide pesticide residue in okra fruits. Their results indicated that simple processes like washing, boiling, soaking, and drying of food facilitated the degradation of tebufenozide pesticide residues in okra fruits. In the same vein. Bian et al. (2020) investigated the effects of washing, peeling, and pickling on the amount of azoxystrobin and meptyldinocap residues in cucumber. They also observed that these simple processes promoted the degradation of these two chiral pesticides. Drying of food is a common processing technique and should be done cautiously as it may end up concentrating the chiral pesticide residues. Some researchers, however, subject dried food to ozone fumigation to ensure efficient removal of chiral pesticide residues (Chanrattanayothin et al., 2019).