There is increased interest in following a healthy lifestyle and consuming a substantial portion of secondary plant metabolites, such as polyphenols, due to their benefits for the human body. Food products enriched with various forms of fruits and vegetables are sources of pro-health components. Nevertheless, in many cases, the level of their activities is changed in in vivo conditions. The changes are strictly connected with processes in the digestive system that transfigure the structure of the active compounds and simultaneously keep or modify their biological activities. Much attention has focused on their bioavailability, a prerequisite for further physiological functions. As human studies are time consuming, costly and restricted by ethical concerns, in vitro models for investigating the effects of digestion on these compounds have been developed to predict their release from the food matrix, as well as their bioaccessibility. Most typically, models simulate digestion in the oral cavity, the stomach, the small intestine and, occasionally, the large intestine. The presented review aims to discuss the impact of in vitro digestion on the composition, bioaccessibility and antioxidant activity of food polyphenols. Additionally, we consider the influence of pH on antioxidant changes in the aforementioned substances.

This paper describes the possibility of electronic nose-based detection and discrimination of volatile compound profiles of coffee from different countries roasted in a Gothot roaster under identical time and thermal regimes. The material used in the study was roasted Arabica coffee beans from Brazil, Ethiopia, Guatemala, Costa Rica, and Peru. The analyses were carried out with the use of the Agrinose electronic nose designed and constructed at the Institute of Agrophysics of the Polish Academy of Sciences in Lublin. The results of the volatile compound profile analysis provided by the Agrinose device were verified with the GC-MS technique. Chemometric tests demonstrated a dominant role of alcohols, acids, aldehydes, azines, and hydrazides in the coffee volatile compound profile. The differences in their content had an impact on the odor profile of the coffees originating from the different countries. High content of pyridine from the group of azines was detected in the coffee from Peru and Brazil despite the same roasting conditions. The results of the Agrinose analysis of volatile substances were consistent and correlated with the GC-MS results. This suggests that the Agrinose is a promising tool for selection of coffees based on their volatile compound profile.

The aim of the study was to analyze the process of roasting coffee beans in a convection–conduction roaster (CC) without a heat exchanger and a convection–conduction–radiation roaster (CCR) with a heat exchanger for determination of the aroma profile. The aroma profile was analyzed using the SPME/GC-MS technique, and an Agrinose electronic nose was used to determine the aroma profile intensity. Arabica coffee beans from five regions of the world, namely, Peru, Costa Rica, Ethiopia, Guatemala, and Brazil, were the research material. The chemometric analyses revealed the dominance of azines, alcohols, aldehydes, hydrazides, and acids in the coffee aroma profile. Their share distinguished the aroma profiles depending on the country of origin of the coffee beans. The high content of pyridine from the azine group was characteristic for the coffee roasting process in the convection–conduction roaster without a heat exchanger, which was shown by the PCA analysis. The increased content of pyridine resulted from the appearance of coal tar, especially in the CC roaster. Pyridine has an unpleasant and bitter plant-like odor, and its excess is detrimental to the human organism. The dominant and elevated content of pyridine is a defect of the coffee roasting process in the CC roaster compared to the process carried out in the CCR machine. The results obtained with the Agrinose showed that the CC roasting method had a significant effect on the sensor responses. The effect of coal tar on the coffee beans resulted in an undesirable aroma profile characterized by increased amounts of aromatic volatile compounds and higher responses of Agrinose sensors.

Oils often have similar properties and can be difficult to identify based on color, smell or taste alone. The present paper suggests the use of Fourier-transform infrared spectroscopy (FTIR) in combination with chemometric methods to explore similarities and differentiate between samples of Moldavian dragonhead oil subjected to different storage conditions. Dragonhead is a plant characterized by very good honey output and ease of cultivation. Principal component analysis (PCA) was applied to a standard, full range of FTIR spectra. Additionally, hierarchical cluster analysis (HCA) was employed to explore the organization of the samples in groups relative to their “proximity” (similarity), by way of Euclidean distance measurement. PC1 and PC2 accounted respectively for 85.4% and 10.1% of the total data variance. PC1 and PC2 were strongly, negatively correlated within the entire spectral range; the only exception was the region corresponding to νs(-C-Hvst, -CH₂) vibrations (aliphatic groups in triglycerides), where PC2 was positively correlated. The use of FTIR spectral analysis revealed noticeable differences in the intensity of bands characteristic of the ageing processes (markers of oxidative processes, etc.) taking place in oleaginous samples and related to the processes of fatty acids oxidation.

Biodegradable materials are used in the manufacture of packaging and compostable films and various types of medical products. They have demonstrated a large number of potential practical applications in medicine and particularly in the treatment of various cardiac, vascular, and orthopedic conditions in adults as well in children. In our research, the extrusion-cooking technique was applied to prepare thermoplastic starch (TPS), which was then utilized to obtain environmentally friendly starch-based films. Potato starch was the basic raw material exploited. Polyvinyl alcohol and keratin were used as functional additives in amounts from 0.5 to 3%, while 20% of glycerol was harnessed as a plasticizer. The processing of the thermoplastic starch employed a single screw extruder-cooker with an L/D ratio of 16. The film blowing process was carried out using a film-blowing laboratory line with L/D = 36. FTIR Spectroscopy was applied for the assignment of the prominent functional groups. The results showed that the processing efficiency of thermoplastic starch with functional additives varied depending on the level of polyvinyl alcohol and keratin addition. Moreover, the FTIR data correlated with the changes in the physical properties of the tested films. The analysis of FTIR spectra revealed several changes in the intensity of bands originating from stretching vibrations characteristic of the –OH substituent. The changes observed depended on the presence/lack of the hydrogen bonding occurring upon interactions between the starch molecules and the various additives used. In addition, notable changes were observed in bands assigned to glycoside bonds in the starch.

Goji fruit (Lycium barbarum L.) has been identified as a polyphenolic compound plant source of noted richness. It also contains polysaccharides, carotenoids, vitamins and minerals, fatty and organic acids. The purpose of the presented research was to produce innovative instant corn gruels with various dry goji berry contents (1, 3 and 5%), to determine the level of included polyphenolic compounds (including individual free phenolic acids) and to assess the antioxidant properties of these functional-food products. A further objective was to identify the optimum value of one of the most important production parameter, the rotational speed of the extruder’s screw during gruel processing. The undertaken chromatographic analysis (LC-ESI-MS/MS) showed a wide variety of available phenolic acids. In the samples with 5% addition of fruit, eight phenolic acids were detected, whereas in the corn gruel without additives, only five were noted. The antioxidant activity, the content of free phenolic acids and the sum of polyphenols increased with increase of the functional additive. For all goji content, screw speeds of 100 and 120 rpm rather than 80 rpm resulted in higher polyphenol amounts and greater Trolox equivalent antioxidant capacity, as well as higher ability to scavenge DPPH.