Cheese and yogurt are two kinds of nutritious dairy products that are used worldwide. The major preservatives in dairy products are sodium benzoate, potassium sorbate, and natamycin. The maximum permitted levels for these additives in cheese and yogurt are established according to Iranian national standards. In this study, we developed a method to detect these preservatives in dairy products by reversed phase chromatography with UV detection in 220 nm, simultaneously. This method was performed on C18 column with ammonium acetate buffer (pH = 5) and acetonitrile (73 : 27 v/v) as mobile phase. The method was carried out on 195 samples in 5 kinds of commercial cheeses and yogurts. The results demonstrated insufficient separation where limit of detection (LOD) and limit of quantitation (LOQ) ranged from 0.326 to 0.520 mg/kg and 0.989 to 1.575 mg/kg in benzoate and sorbate, respectively. The correlation coefficient of each calibration curve was mostly higher than 0.997. All samples contained sodium benzoate in various ranges. Natamycin and sorbate were detected in a remarkable amount of samples, while, according to Iranian national standard, only sorbate is permitted to be added in processed cheeses as a preservative. In order to control the quality of dairy products, determination of preservatives is necessary.

The aim of this study was to analyze the effect of cooking method on thiamin (B1), riboflavin (B2), and pyridoxine (B6) vitamin content of rice samples consumed in Iran by using high‐performance liquid chromatography technique. The amount of B1, B2, and B6 obtained ranged from 2.98 to 15.89, 1.15 to 22.19, and 0.96 to 4.44 μg/g, respectively, for the boiling method. In the traditional method, these vitamins had a concentration between 4.09 and 29.55, 4.87 and 16.19, and 1.52 and 12.18 μg/g, respectively. However, limit of detection (LOD) values for B1, B2, and B6 vitamins were 0.159, 0.090, and 0.041 μg/ml, respectively. Multivariate methods and heatmap visualization were applied to estimate the correlation among the type and amount of vitamins and cooking methods. According to heatmap findings, B1 and B6 vitamins and the cooking method had the closest accessions, representing that this variable had similar trends. Nevertheless, it can be concluded that the traditional cooking method can maintain more vitamins in rice samples.

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Malt beverage is one of the most popular drinks in the world. Recently, consumption of non-alcoholic beverages has expanded significantly in many countries. The permitted level of alcohol in malt beverage is less than 0.5% by Iranian National Standards. In this study, a method was developed to determine ethanol content in malt beverages by FTIR, equipped with Horizontal Attenuated Total Reflectance (H-ATR). Here, the Limit Of Detection (LOD) and Limit Of Quantification (LOQ) were 0.07% and 0.23%, respectively. The correlation coefficient of calibration curve was higher than 0.999. Fifty commercial malt beverages from six brands (five Iranian and one imported brand) and three types of flavored malt beverage (classic, equatorial, and lemon) were assessed. The average detected ethanol amount in samples was 0.19%, varying between 0.00-1.47percent. The results showed that the amount of ethanol in lemon malt drinks was more than the maximum permitted limit; that could be attributed to the usage of ethylene glycol for extraction of lemon flavor.