جستجوی مقالات مرتبط با کلیدواژه « قهوه » در نشریات گروه « صنایع غذایی »

Coffee is one of the most popular beverages in the world, which contains large amounts of bioactive compounds and micronutrients that have beneficial effects on human health.Raw and unprocessed coffee beans are green and have a weak flavor and must be roasted before consumption to achieve the desired taste and flavor. The composition of coffee varies greatly during roasting and many factors, including the roasting method, have a great impact on the type and amount of compounds in coffee. Microwave as one of the roasting methods has advantages that have expanded its application in food processing. The aim of this study was to compare the effect of using the microwave as one of the roasting methods on the physicochemical including the moisture content, hardness, instrumental color, antioxidant activity, type and amounts of aromatic compounds, and sensory properties of green coffee beans with the common method of using hot air. For this purpose, 200 g of coffee beans of uniform size were used for each one of the roasting treatments.

In the present study, Arabica green coffee (Coffea arabica) beans produced in Brazil were roasted using direct oven hot-air (220 °C) for 15 minutes and various microwave powers (650, 750, and 900 watts) for 1.5 minutes. Moisture content was measured by accurately weighing ground coffee samples after drying them in an oven at 105 °C until constant weight. The hardness of coffee beans was investigated using a wedge probe (A/WEG) connected to a Texture Analyzer TA-XT2i equipped with a load cell of 25 kg. Instrumental color characteristics including lightness (L*), redness (a*), and yellowness (b*) were measured using a Konica Minolta Colorimeter CR-400. The antioxidant activity of coffee beans was assessed by DPPH• radical scavenging assay. The aromatic compounds of coffee samples were extracted and identified by the solid-phase microextraction (SPME) method and gas chromatography-mass spectrometry (GC-MS), respectively. Organoleptic attributes of brewed coffee samples including appearance color, odor intensity, taste, and overall acceptability were evaluated with a group of 10-trained panelists using an 11-point scale. All experiments were carried out using a completely randomized factorial design and the data reported were the mean of a minimum of three replicates.One-way analysis of variance (ANOVA) test was taken using SPSS Software and Duncan’s multiple range test was used to show significant differences of the mean values at P ≤ 0.05.

The results of data analysis showed that the moisture content of coffee beans was significantly reduced by roasting and the lowest moisture content was observed in coffee roasted by microwave at 900 watts. The results also showed that roasting reduced the hardness of coffee and microwave-roasted beans had less hardness and the lowest texture hardness was observed in microwave-roasted coffee beans at 900 watts. Roasting decreased the lightness (L*) and increased the intensity of redness (a*) and yellowness (b*) of coffee beans, and in microwave-treated samples at higher powers, more differences were observed in the instrumental color characteristics of roasted coffee with the oven. The results revealed that the roasting process reduced the antioxidant activity of coffee in different concentrations; however, microwave-roasted coffees had more antioxidant activity than oven-roasted coffees. The results of the analysis of volatile compounds of coffee samples using solid-phase microextraction method by gas chromatography-mass spectrometer (SPME-GC/MS) showed that the content of total acidic compounds in roasted beans was significantly reduced compared to green coffee beans, while the amounts of alcoholic, ketone, aldehyde, furan, pyrazine and phenolic components in roasted coffees raised significantly compared to green coffee. The results showed that the roasting method had a significant effect on the type and amount of volatile compounds in coffee (p < 0.05). During the roasting process, some compounds were completely destroyed and some new compounds appeared instead. In the present study, the highest amount of volatile compounds was observed in coffee roasted by microwave at 650 watts. Furfuryl alcohol, 2-methylpyrazine γ-butyrolactone, and Pyridine were the predominant volatile compounds in roasted coffee. The results of the sensory evaluation showed that roasting had a significant effect on the sensory properties of coffee, so that roasting increased the acceptance of the appearance color of coffee, and coffee roasted by oven and microwave (650 watts) had the highest score. In addition, coffee roasted by microwave with a power of 650 watts had a significantly higher odor and taste score. Roasted coffee with 650 watts of microwave and oven had the highest overall acceptability, while samples prepared with 900 watts of the microwave with green coffee had the lowest overall acceptability.

In conclusion, based on the results of the present study, it could be stated that the use of microwave power at 650 watts due to the ability to create more aromatic components in coffee beans, better sensory acceptance, and more antioxidant activity could be a suitable method for roasting coffee beans.

Date seeds (also known as pits and kernel) are among the most important wastes which are generated during direct consumption or from the date processing industries. Despite the presence of several nutrients and bioactive compounds and their subsequent beneficial health effects, these by-products are frequently discarded to use as soil fertilizer or as feed for livestock. Roasting opens a cost-effective way to include date seed in the human diet. The aqueous extract of roasted date seed represented a coffee-like beverage. Date seed coffee has a relatively low acceptance among consumers and is usually supplemented with a variety of additives to improve the taste. Therefore, due to rising the global coffee price, in the present studywe aimed to substitute Arabica beans with roasted date seeds in order to make a coffee beverage similar to Coffea Arabica boiled coffee brew.  Substitution with roasted date seed resulted in lower lipids, protein and caffeine of coffee brews as the values were decreased from 330.67, 956.75, 76.51 mg/100 mL in Coffea Arabica (100%) to 192.61, 149.00, 45.59 mg/100 in date seed coffee (100%), respectively. Higher amounts of date seed also resulted in lower pH and acrylamide content. Accordingly, pH was decreased from 5.7 in D100 to 4.4 in A100. Acrylamide content was attenuated from 5.06 µg/100 mL in A100 to 1.71 µg/100 mL in D100. Reduction in viscosity was also observed from 0.93 (A100) to 0.86 mPa.s (D100). The mean value of the color parameter including L*, a* and b* in the 100% Coffea Arabica brew was more than the 100% date seed coffee, which indicated that the coffees brewed from date seeds in different proportions were brighter and had higher red and yellow color parameters. Substitution with date seed had less effect on the total phenol content as TPC of coffees ranged from 28 to 42 mg/100 mL for 100% date seeds brew and Coffea Arabica brew, respectively. On the other hand, the flavonoid content (TFC) of coffees was significantly affected by the amount of date seeds (5 to75 mg/100 mL for 100% date seeds and Coffea Arabica brew, respectively). All brews have high antioxidant activity. For DPPH the highest results (88/9 %) were obtained in the coffee brewed from 100% date seeds, while the FRAP value it was vice versa. The results of sensory evaluation indicated a high similarity among A100 and D10 coffees as parameters such as aroma, color and texture (concentration) of coffee were evaluated appropriate. The results also showed that substituting Coffea Arabica up to 35% with roasted date seeds can improve the overall acceptance of the coffee brews by reducing bitterness. In general, the ability to replace Coffea Arabica with date seeds up to 10 and 35% was reported acceptable in terms of sensory characteristics, as the color and aroma were similar to 100% Coffea Arabica. Besides that due to reduced bitterness, the overall acceptance were almost high.

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.
 
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.
 
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.

Coffee is a rich source of methylxanthines, especially caffeine, hydroxy-cinnamic acids, especially chlorogenic acids and, for health benefits has been considered. In this research the effect of ultrasound pretreatment and then roasting process on extraction of phenolic compounds, flavonoids and free radicals scavenging capacity as well as the effect of solvent composition on the extraction phenolic and flavonoid contents were evaluated. The results of this research showed that ultrasound pretreatment can increase the extraction of phenolic compounds up to the 11.99% for a frequency of 20 kHz, 22.89% for 40 kHz and 13.52% for frequencies of 60 kHz frequency. The results also showed that ultrasound pretreatment can increase flavonoid extraction for the frequencies 20, 40 and 60 kHz; 13.65, 18.47 and 30.04 percent respectively compared to the control sample. The highest extraction of phenolic compounds related to the frequency of 60 kHz and isopropanol 60%, which was 31.51 mg per gram of Gallic acid. Ultrasound pretreatment had significant effect on the percentage of free radicals scavenging of DPPH (p