Paniz Khaloo Kermani; Marzieh Moeenfard; Reza Farhoosh; Arminda Alves
Abstract
[1]Introduction: Date seed are considered as a valuable by-product from Phoenix dactylifera L. which played an important role in the economy and social life of the people of the Middle East and North Africa region. They consist mostly of carbohydrates, fatty acids and proteins as well as phenolic compounds. ...
Read More
[1]Introduction: Date seed are considered as a valuable by-product from Phoenix dactylifera L. which played an important role in the economy and social life of the people of the Middle East and North Africa region. They consist mostly of carbohydrates, fatty acids and proteins as well as phenolic compounds. Despite the presence of various beneficial bioactive compounds, they are usually discarded or are utilized as animal fodder. Therefore, explore the effective methods to incorporate date seeds in the human diet is a great of interest. Roasting provides a low cost and easy approach to add value to these wastes as roasted date seed powder is being used in the Arabian region to make “date seed coffee”. However, along with color and aroma changes, carcinogenic substance such as acrylamide may also formed during the roasting process. To date, no data have been published on the analysis of acrylamide in the roasted date seeds and respective brews. Therefore, the objective of the present study was development of an analytical method for determination of acrylamide in various date seeds varieties and their respective moka brews for the first time. Besides, other parameters related to the roasting process such as the color parameters and melanoidins content were also determined and compared with values obtained from Arabica coffee. Materials and methods: For this purpose 5 different varieties of roasted date seeds including Shahani, Zahedi, Kabkab, Mazafati and Estamaran as well as Arabica coffee were used for coffee brewing. For acrylamide determination in solid samples, they were firstly extracted using hot deionized water. Afterwards, 5 mL of sample (extract or coffee brew) was placed in a 15 mL falcon and extraction solvents including acetonitrile (10 mL), hexane (5 mL) along with 1 g of NaCl and 4 g of MgSO4 were added. After mixing on vortex for 1 min and centrifugation (5 min, 5000 rpm), 2 mL of the supernatant was cleaned using appropriate combination of sorbents (100 mg PSA, 50 mg C18 and 50 mg SAX) along with 0.30 g of MgSO4.The cleaned supernatant was filtered and analyzed using high-performance liquid chromatography coupled with a photodiode array detector (HPLC-PDA) at 202 nm. The injection volume was 20 μL. The chromatographic separations were performed on a Eurospher 100-5 C18 column (250× 4.6 mm). Optimization was performed according to the type of organic solvent (acetonitrile and methanol), the percentage of organic solvent in the mobile phase (10, 5, 3% v/v) and the flow rate (0.1, 0.7, 0.5 mL/min). The color parameters (using photography and help of ImageJ software) and melanoidin content (spectrophotometrically at 420 nm) were also determined. Results and discussion: The results indicated that the water/acetonitrile with a ratio of 97:3 and a flow rate of 0.7 mL/min permitted the acceptable separation of the acrylamide peak from the interfering compounds. The LOD and LOQ of optimized analytical method were 9.1 and 30.62 µg/kg, respectively. The suggested HPLC/PDA method is promising for analysis in order to guarantee the quality control of acrylamide. The presence of acrylamide in all roasted date seeds was observed. Accordingly, acrylamide content in Arabica coffee (1825.23± 17.44 µg/kg) was significantly higher than those obtained from date seeds varieties. The amount of acrylamide in different types of date seeds varied from 360.99± 4.15 to 129.43± 2.37 µg/kg, being Kabkab and Mazafati as the highest and lowest values, respectively. Moka brews prepared from roasted date seeds demonstrated the presence of acrylamide in the range of 25-68 µg/L. The highest level of melanoidin were observed in Arabica coffee followed by Shahani, Zahedi, Kabkab, Mazafati and Estamaran, respectively. In the most cases, an inverse relationship was observed between the acrylamide and melanoidin content in roasted date seeds. For example, Shahani had low acrylamide and high melanoidin content. The study of color parameters revealed that the parameters a* and b* largely follow the pattern of melanoidin, so with increasing the amount of a* and b*, the amount of melanoidin also increased in the samples.
Marzieh Moeenfard; Paniz Khaloo Kermani; Shima Jaldani; Ali Sharif
Abstract
Introduction: Coffee is the most important and popular beverage in the world. The main differences between coffee and other beverages like tea is the variety of applied brewing techniques. Coffee is a complex chemical mixture of compounds including, caffeine, as a natural alkaloid. Besides its beneficial ...
Read More
Introduction: Coffee is the most important and popular beverage in the world. The main differences between coffee and other beverages like tea is the variety of applied brewing techniques. Coffee is a complex chemical mixture of compounds including, caffeine, as a natural alkaloid. Besides its beneficial effect including enhancement in mental activity and alertness as well as improving the cognitive functioning, caffeine indicated adverse effects such as headache and anxiety when it is consumed in higher quantity. In terms of chemical extraction, it can be also considered as an interference when analyzing other pollutants, therefore, its removal from extract is of great interest. Therefore, the present study was designated to investigate the caffeine content of 18 various coffee-related products. Furthermore, the effect of two extraction techniques (QuEChERS and conventional) on caffeine removal from coffee extract was investigated. Materials and Methods: Coffee brews including classical (boiled, French, moka and filtered coffees) and commercial brews (various types of espresso as well as instant and iced coffees) were prepared using Robusta, Arabica coffee or commercial powders. In conventional extraction approach, a 2.5 mL of coffee sample was treated with 0.1 mL each of Carrez solutions I and II to clarify the sample. The total volume was brought to 50 mL by the addition of 10% methanol (v/v). After centrifugation, the supernatant was filtered and analyzed using high-performance liquid chromatography coupled with a diode array detector (HPLC-DAD) at 273 nm. In QuECHERS approach, the effect of extraction solvent (acetonitrile and ethyl acetate) and sorbents (primary and secondary amines and, octadecyl silane) on caffeine removal was investigated and was compared to conventional approach as reference method. The extraction and clean-up were accomplished by two types of solvents and sorbents in the presence of sodium chloride and magnesium sulfate. Finally, caffeine was determined using HPLC-DAD at 273 nm. Results and Discussion: According to the results, the two coffee varieties (Arabica and Robusta) were clearly separated by their caffeine contents as Robusta presented higher values in all classical brews. Among the classical brewing techniques, the coffee with the highest content of caffeine was moka brewed from roasted Robusta coffee, with a mean value of 1044 ± 26 mg/L. The caffeine content was also determined per serving (cup size) to determine the actual content received by consumers. Accordingly, among traditional brews the most caffeine-rich coffee was espresso type pod coffee, with a mean value of 1371 ± 16 mg/L, equivalent to 56 ± 0.6 mg/40 mL of serving size. The lowest mean caffeine content (13.4 mg / 240 mL) was found in iced coffee. With regards to caffeine extraction, with recovery of 101%, the conventional method was the most efficient approach for caffeine determination. Caffeine significantly reduced (around 20% compare to conventional approach) when QuEChERS was used as extraction technique which could be valuable for analysis of pesticides, which are usually present in small quantities in food samples like coffee. In general, the use of acetonitrile as well as the simultaneous application of PSA and C18 resulted in a significant decrease in caffeine content of Robusta coffee extract.Here, different coffee brews were assessed and compared for their caffeine content (mg/mL and mg/serving). Technical differences like coffee varieties, coffee/water ratio or method of brewing (pressurized, fusion, filtering, etc) led to coffee brews with different caffeine profiles. Interestingly, despite the high concentration of caffeine in espresso types brews, they provided moderate coffee in terms of caffeine content per cup. On the other hand, classical methods in particular boiled, French and filtered Robusta coffee were rich in terms of caffeine per cup. When studying caffeine extraction, the efficiency of conventional method was significantly superior to QuEChERS approach as caffeine significantly reduced when QuEChERS was used as extraction method.
