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This study aimed to assess the impact of roasting degree on antioxidant and metabolic parameters in vitro and in vivo. In vitro, we evaluated radical scavenging, lipid peroxidation, and the activity of digestive enzymes (α-glucosidase, α-amylase, and lipase). In vivo, we first examined coffee's effect on carbohydrate and lipid absorption in healthy rats, followed by a chronic evaluation of metabolic disorders and antioxidant markers using a diet-induced obesity model. In vitro results revealed that increased roasting degree reduced the antioxidant capacity of coffee brews. All brews showed lower inhibition of α-glucosidase and α-amylase, and lipase inhibition compared to the positive control (acarbose or orlistat). In vivo, all roasting degrees consistently reduced postprandial glucose levels by 20%. Notably, coffee with a high roasting degree (HRD) decreased serum triglycerides (TG) by ∼44% after a lipid load, while other roasts did not. Chronic administration of unroasted (UN) or HRD coffee significantly reduced weight gain compared to the obese control (∼15% and ∼10%, respectively). Notably, all coffee samples improved lipid metabolism parameters. UN and HRD coffee significantly decreased adipocyte volume by 58% and 48%, respectively, compared to the obese control. Additionally, all groups exhibited less than 30% hepatic lipid droplets independent of roasting degree. HRD treatment notably increased liver catalase (CAT) activity and reduced lipid peroxidation in serum (∼90%), liver (∼59%), and adipose tissue (∼37%) compared to the obese control group. These findings suggest that HRD in coffee may confer certain biological advantages.

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Agtron method is widely used in the industry to determine roasting degrees in whole and ground coffee but it suffers from some inconveniences associated with unavailability of equipment, high cost, and lack of reproductive results. This study investigates the feasibility to determine roasting degrees in coffee beans and ground specialty coffees using near-infrared (NIR) spectroscopy combined with multivariate calibration based on partial least squares (PLS) regression. Representative data sets were considered to cover all Agtron roasting profiles for whole and ground coffees. Proper development of models with outlier evaluation and complete validation using parameters of merit such as accuracy, adjust, residual prediction deviation, linearity, analytical sensitivity, and limits of detection and quantification are presented to prove their performance. The results indicated that predictive chemometric models, for intact coffee beans and ground coffee, could be used in the coffee industry as an alternative to Agtron, thus digitalizing the roasting quality control.

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Coffee consumption has been investigated as a protective factor against prostate cancer. Coffee may be related to prostate cancer risk reduction due to its phytochemical compounds, such as caffeine, chlorogenic acids, and trigonelline. The roasting process affects the content of the phytochemicals and undesired compounds can be formed. Microwave-assisted extraction is an alternative to conventional extraction techniques since it preserves more bioactive compounds. Therefore, this study aimed to evaluate the phytochemical composition and the putative preventive effects in prostate cancer development of coffee beans submitted to four different coffee-roasting degrees extracted using microwave-assisted extraction. Coffea arabica green beans (1) were roasted into light (2), medium (3) and dark (4) and these four coffee samples were submitted to microwave-assisted extraction. The antioxidant capacity of these samples was evaluated by five different methods. Caffeine, chlorogenic acid and caffeic acid were measured through HPLC. Samples were tested against PC-3 and DU-145 metastatic prostate cancer cell lines regarding their effects on cell viability, cell cycle progression and apoptotic cell death. We found that green and light roasted coffee extracts had the highest antioxidant activity. Caffeine content was not affected by roasting, chlorogenic acid was degraded due to the temperature, and caffeic acid increased in light roasted and decreased in medium and dark roasted. Green and light roasted coffee extracts promoted higher inhibition of cell viability, caused greater cell cycle arrest in S and G2/M and induced apoptosis more compared to medium and dark roasted coffee extracts and the control samples. Coffee extracts were more effective against DU-145 than in PC-3 cells. Our data provide initial evidence that among the four tested samples, the consumption of green and light coffee extracts contributes to inhibit prostate cancer tumor progression features, potentially preventing aspects related to advanced prostate cancer subtypes.

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Coffee brew presents sensory, stimulatory and antioxidant properties highly appreciated by consumers, despite being associated with an increase in the level of blood cholesterol due to the effects of the diterpenes, especially cafestol, present in the lipid fraction. Although it is believed that the paper filter retains the brew diterpenes, new studies have shown that sometimes coffee filtered through paper can also increase the blood cholesterol level, putting in doubt the efficiency of the paper filter in retaining the diterpenes. Thus the objective of the present study was to verify the distribution of cafestol between the paper filter, the spent coffee and the coffee brew itself, from two coffee samples containing high and low cafestol contents selected from 13 samples of different cultivars and from different locations. In addition, the effect of the roasting degree on the cafestol contents of the roasted coffee was evaluated and the relationship between particle size of the roasted coffee and the extraction of solids. The highest cafestol content was found in the lightly roasted coffee, and the coffee brew presented higher solids contents when the particle size of the coffee powder was below 500µm. The results showed that of the initial cafestol concentration present in the roasted coffee, the paper filter retained 12.41%, the spent coffee 87.45% and the brew 0.15%. Thus, one can conclude that the greater part of the coffee cafestol is retained by the spent coffee, due to the low extraction of the lipid fraction by the hot water.

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