Elsevier

Atmospheric Environment

Volume 74, August 2013, Pages 194-198
Atmospheric Environment

Additive impacts on particle emissions from heating low emitting cooking oils

https://doi.org/10.1016/j.atmosenv.2013.03.038Get rights and content

Highlights

  • Particle emissions were compared for cooking oils with and without additives.

  • Sea salt, table salt and black pepper reduced the particle number emission rates.

  • Tumeric and garlic powder had no effect on particle emissions from the heated oil.

Abstract

The effect of five additives, including table salt, sea salt, black pepper, garlic powder, and turmeric, on the emission of PM2.5 and ultrafine particles (UFP) from heated cooking oil (200 °C) were studied. One hundred milligrams of the additives were added individually to either canola or soybean oil without stirring. Black pepper, table salt, and sea salt reduced the PM2.5 emission of canola oil by 86% (p < 0.001), 88% (p < 0.001), and 91% (p < 0.001), respectively. Black pepper, table salt, and sea salt also decreased the total particle number emissions of canola oil by 45% (p = 0.003), 52% (p = 0.001), and 53% (p < 0.001), respectively. Turmeric and garlic powder showed no changes in the PM2.5 and total number emissions of canola oil. Table salt and sea salt, decreased the level of PM2.5 emissions from soybean oil by 47% (p < 0.001) and 77% (p < 0.001), respectively. No differences in the PM2.5 emissions were observed when other additives were added to soybean oil. Black pepper, sea salt, and table salt reduced the total particle number emissions from the soybean oil by 51%, 61% and 68% (p < 0.001), respectively. Turmeric and garlic powder had no effect on soybean oil with respect to total particle number emissions. Our results indicate that table salt, sea salt, and black pepper can be used to reduce the particle total number and PM2.5 emissions when cooking with oil.

Introduction

Cooking emissions results in human exposure to both PM2.5 (particulate matter less than 2.5 μm) and ultrafine particles (UFP) (Abdullahi et al., in press). Dennekamp et al. (2001) found that gas and electric cooking generate ultrafine particles. Cooking on gas or electric stoves and toaster ovens were found to be among the highest sources of indoor UFP exposure (Wallace and Ott, 2010). Hussein et al. (2006) found that cooking and tobacco smoking were the main sources of indoor particles in a home. Among cooking activities, frying has been found to be responsible for the highest particle emissions (Zhang et al., 2010; Olson and Burke, 2006; See and Balasubramanian, 2008; Lee et al., 2001; Li et al., 2003).

Task ventilation and/or changes in cooking methods can be used to reduce exposure to cooking emissions. Howard-Reed et al. (2003) found that using a central fan and electrostatic precipitator (ESP) reduced particles number concentrations generated by indoor sources by 25–50% and 55–85%, respectively, compared to the fan-off conditions. A similar observation was reported by Wallace et al. (2004) in that ESP, mechanical air filtration and central heating and air conditioning reduced the indoor ultrafine and fine particle concentrations from cooking 51%, 23%, and 14%, respectively. An in-duct ESP resulted in PM10 reductions between 30 and 70% in five homes (Fugler and Bowser, 2002).

See and Balasubramanian (2008) conducted a compositional analysis of cooking fumes. They found that cooking with water compared to cooking with oil reduces the exposure to carbonaceous particles, PAHs and toxic metals but increases the exposure to inorganic anions such as F, Cl, and SO42. See and Balasubramanian (2008) found that steaming reduced the PM2.5 concentration level by about 65% in comparison to deep frying. Zhang et al. (2010) studied the black carbon, ultrafine particle, and PM2.5 concentrations generated by different cooking styles. Their results indicate that water-based cooking (Italian style) reduced the level of black carbon, UFP, and PM2.5 concentrations by 75%, 93%, and 85%, respectively, compared to oil-based cooking (Chinese style). Zhang et al. (2010) and Buonanno et al. (2011) found that the fat content of the food was related to the production of cooking particles.

Emissions of particles from heated cooking oil depend on the selection of oils. Amouei Torkmahalleh et al. (2012) found that soybean, canola, and safflower oils reduced the PM2.5 concentration by 90% and ultrafine particle (UPF) number concentration by 95% as compared with coconut, olive, peanut and corn oils. Reducing the surface area of the oil also reduced emissions with the emission rate directly proportional to the oil surface area (Amouei Torkmahalleh et al., 2012). Thus, the emission flux (mass time−1 area−1) can be calculated by dividing the emission rate by the surface area.

Often, additives are added during frying and cooking to improve the taste of the cooked foods. Black pepper, table salt and sea salt are commonly used additives in many cultures. Turmeric is a yellow ingredient used extensively in the Middle Eastern and South Asian countries such as Iran and India and is also commonly available in the western countries. The yellow active constituent of turmeric is curcumin that has shown antimutagenic and anticarcinogenic activity (Shukla et al., 2002; Nagabhushan and Bhide, 1992). Karadas and Kara (2012) performed an elemental analysis of turmeric and determined the elemental compounds of turmeric to be Ca, Mg, Fe, Sr, Mn, Zn, Ba, Cu, Ni, Cr, Co, As, Cd. Among these elements, Ca was found to have the highest concentration following with Mg.

In western style food, garlic is often added during cooking and frying. The main compound of garlic is diallyl disulfide (DADS), which improves digestibility and energy use efficiency (Klevenhusen et al., 2011). Garlic and black pepper contain variety of elements such as Ca, Fe, Mn, Zn, Cu, Cd, Pb, P, Cl, S, Na, Mg, Al, P, K, Ti, Cr, Co, Ni, Se, Rb, Sr and Sn (Al-Bataina et al., 2003; Gonzalvez et al., 2008). Potassium was found to be the element in garlic and black pepper with the highest concentration ranging from 0.16 to 2.1% (w/w) (Gonzalvez et al., 2008).

The objective of the present study is to systematically investigate the particle number and mass concentrations and emission rates from major cooking oils in the presence of additives such as table salt, sea salt, black pepper, garlic powder and turmeric. The results from this study can provide guidance on choosing proper combinations of oil and additives that result in lower emission fluxes when heated.

Section snippets

Particle emission experiments for different oils

Two commercial cooking oils, soybean oil and canola oil, were investigated to determine the PM2.5 and total particle number concentration and emission fluxes in the presence of five additives: table salt, sea salt, black pepper, garlic powder and turmeric. Soybean and canola oil were selected because they are among the oils with the lowest emission rates when heated (Amouei Torkmahalleh et al., 2012). The oils and additives were purchased locally and stored in the laboratory without

Canola oil

Fig. 1 shows the PM2.5 concentration variation with temperature for pure canola oil and the mixture of canola oil with table salt, sea salt, black pepper, garlic powder, and turmeric. Fig. 1 shows that as temperature decreases, the PM2.5 concentration decreases. The largest differences among the factors are observed at the highest temperature tested. However, no statistically significant differences were observed between pure canola oil and canola oil with either garlic powder or turmeric at

Discussion

The table salt and sea salt consistently reduced emissions from the oil for all conditions tested. The sea salt reduced the PM2.5 concentration substantially more than table salt when added to soybean oil. However, no difference between the two salts was observed for canola oil. The finding of reduced emission with salt additive is consistent with the chemical properties of dissolved salts in oil. During the experiments, the salts were visually observed to dissolve almost completely in the oil.

Conclusions

The purpose of this work was to separate and study the effect of additives on particle emissions from cooking oil. Our results indicate that adding 100 mg of table salt, sea salt and black paper added to 200 mL of canola and soybean oils reduce the total particle number and PM2.5 emission rates and fluxes. However, adding more or less mass of the salts did not change the emission rate and fluxes. This reduction in the total number and PM2.5 emission fluxes could be due to reduction of the vapor

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