Strong acids convert aflatoxin to its hemiacetal form through hydration. Pons et al. studied acid conversion of AFB and AFG to AFB and AFG respectively, forms that are much less toxic. They found that the rate of conversion increased as the pH decreased or the temperature increased. It was also observed that AFB and AFG were less susceptible to acid degradation than AFB and AFG The effectiveness of acids to degrade aflatoxins was demonstrated in naturally contaminated peanut meal. The addition of 3-M hydrochloric acid during the manufacture of hydrolyzed vegetable proteins in a reactor with steam at 129°C and 160 kPa totally degraded aflatoxins without the production of toxic or mutagenic compounds. In another study, 5-N hydrochloric acid completely destroyed aflatoxin B in peanut flour at 100°C in sealed culture tubes placed in an oil bat.

Both studies show that an aflatoxin-free hydrolyzed vegetable protein could be made from aflatoxin-contaminated peanuts under certain conditions. Not all acids are as effective in destroying aflatoxin-contaminated commodities. Addition of citric acid to milk, prior to ultrafiltration or diafiltration, did not enhance the removal of aflatoxin M

At a concentration of 3N salicylic, sulfamic, and sulfosalicylic acids reduced 1-ppm AFB by 90% in 25% moisture sorghum stored for 72 hours at 25°C in cotton-stoppered Erlenmeyer flasks. In the same study, a concentration of 5-N anthranilic, benzoic, boric, oxalic, and propionic acids also reduced 1-ppm AFB by 90% or more in sorghum. Although treatment with strong acids has been shown to effectively degrade AFB acid treatment has little or no effect on AFB or AFG and AFB is still toxic.

Source:Aflatoxin and Food Safety Edited by Hamed K. Abbas CRC Press 2006

Commercial standards for olive oils are established by the International Olive Oil Council (IOOC). Chemical tests as well as organoleptic assessments are taken into consideration. Acidity, expressed in grams of free oleic acid per gram of oil is a measurement of hydrolysis (deterioration) of the oil. Titratable acidity of oils increases in the later stages of ripening, when fruit are softer and more susceptible to pathogens. Oil extracted from fruit batches containing decayed olives show high acidity, due to the action of lipases of microbial source present in raw material stored for prolonged periods under inadequate conditions.

In contrast with other vegetable oils, which are refined prior to consumption, virgin olive oil is consumed crude, and exhibits a fragrant aroma. Olive oil flavor is the product of a complex mixture of volatiles and phenolic compounds. Olive cultivar, growing location, harvest method, and ripening stage of the olives all influence the flavor of olive oil.

Most of the olive oil volatiles are generated from linoleic and linolenic hydroperoxides through the lipoxygenase pathway upon the disruption of tissues carried out during crushing and mixing operations. Many six-carbon atom volatile compounds are formed, including aldehydes, ketones, hydrocarbons, and esters. About 60–80% of the volatiles consist of C aldehydes [hexanal, 3(Z)-hexenal, 2(E)-hexenal], alcohols [hexanol, 3(Z)-hexenol, 2(E)-hexenol], and their esters [hexyl acetate, 3(Z)-hexyl acetate] . Most of the virgin olive oil market is represented by blends of oils from different olive cultivars. Nevertheless, there is a small market for specialty monovarietal oils.

Analyses of sensory descriptors or volatile and phenolic constituents are important in characterizing monovarietal virgin olive oils (Aparicio and Luna, 2002). In an evaluation of virgin olive oils extracted from Picual olives conventionally and organically grown, the overall quality of the organic oils was considered higher; lower acidity, higher stability, and higher organoleptic scoring were reported.

Source: Garcia, E., Luh, B. S., Martin, H., 2005, Olives In Processing Fruits: Science and Technology, Dianne, M. B., Laszlo, S.,  Hosahalli, R (Eds), CRC Press, Florida

Scientists with the University of Texas School of Public Health have released a study on persistent organic pollutant (POP) levels in the U.S. food supply. The study, published in Environmental Health Perspectives in June, showed that the chemicals are found in the many types of food even though their use has been banned. This study confirms the results of a European Union study on chemicals in food that was recently reported.

Persistent organic pollutants are chemicals that do not break down in the environment; this is why they tend to end up in food, especially in animals higher up the food chain. Many POPs have had wide consumer and industrial use in the past 50 years, which explains their ubiquitous existence in soil, water, air, and food.

The scientists looked at levels of three major groups of contaminants, PFCs, PCBs, and pesticides. Perfluourinated Compounds (PFCs) were used in aerosols and sprays until they were recently phased out by manufacturers.  Polychlorinated Biphenyls (PCBs) were used in industrial chemicals and electrical work until the 1970s, but they can still be found in humans and animals today. DDT, the miracle pesticide from the early to mid 20th century, is another type of persistent pollutant. All of these chemicals have been shown to have toxic affects, including decreased fertility, cancer, and hindered neurologic development.

All food samples were purchased from Dallas supermarkets. Thirty-one types of food, including produce, meat, and dairy, were tested for 32 pesticides, seven PCBs, and 11 different PFCs. These organic pollutants were found to be widespread in the different types of food. PFCs were found in 17 of the foods; six of the seven types of PCBs were found in salmon and canned sardines. Pesticides were found in 23 of the 31 foods tested.

The levels of chemicals varied dramatically in the different types of food. Foods with a high fat content had relatively high levels of pesticides. The highest levels of DDT were found in whole milk yogurt; the greatest numbers of PCBs found primarily in fish, especially salmon; and that there were PFOAs in more than one-half the samples, especially in olive oil. Concentrations of one type of pesticide, dieldrin, ranged from 0.028 nanograms per gram in whole milk to 2.3 ng/g in catfish fillets. When compared with produce and other types of meat, fish was usually found to have much higher levels of contaminants.

The researchers then looked at the overall consumption of different foods to calculate the daily intake of persistent organic chemicals for the average American. The total daily consumption of DDTs was 263 ng/day, mainly from dairy products. The daily consumption of other chemicals was lower, with PCBs at 33 ng/day. For all chemicals measured, however, the total daily intake was not higher than the EPA’s reference doses or the European Union’s highest acceptable level for pesticide contamination of food.

The researchers pointed out, however, that while the effects of each single chemical compound are known, there is no research on the effects of having a complicated mixture of many organic pollutants. In reality, it’s unlikely that a person would find themselves exposed to only one of these chemicals. Potentially toxic interactions between the chemicals, even when present at lower levels, is an issue that has not been researched.

For the future, scientists in the study called for better monitoring and studying of chemical contaminants in food. Previous USDA studies have not tested the same foods from year to year, so comparing data has not been possible. In other studies, only one type of food had been tested, which did not allow researchers to get an idea of how much contaminant was being ingested overall.

At the end of their paper, the researchers warned about not only watching for these known contaminants, but also considering new organic pollutants that are entering the food system: “Our study shows that U.S. food is contaminated with a wide range of chemicals, including pesticides, PFCs, and PCBs, and that expanding the current monitoring beyond pesticides to include emerging pollutants is warranted.”