The effect of drying methods on the concentration of compounds in sage and thyme

The Quality of the Herbal Product Obtained in the Pressure Agglomeration Process

The aim of the conducted research was to evaluate the impact of the pressure agglomeration process of lemon balm (Melissa officinalis L.) on the mechanical properties of the obtained product, its antioxidant capacity, and total polyphenol content. Two fractions of lemon balm were isolated with particle sizes of 0.5-2.5 mm and 2.5-5.0 mm. The isolated fractions were compacted using a Fritz Heckert EU 20 hydraulic press, applying compaction pressures of 100, 150, and 200 MPa. A closed die was used, with 2 g of the plant sample introduced each time. The mechanical properties of the obtained product were determined through an abrasion test and diameter test (Brazilian method) using the MTS Insight 2 testing machine. The total polyphenol content and antioxidant activity were measured using the ABTS method, both directly after product preparation and after a 6-month storage period. The compaction of lemon balm resulted in an increase in total polyphenol content and antioxidant properties compared to the unpressed raw material. The obtained product displayed favorable mechanical properties, as confirmed by the conducted mechanical tests. Regardless of the applied herb fraction, an agglomeration pressure of 200 MPa is particularly recommended.

Exploring Chemical Variability in the Essential Oils of the Thymus Genus

Thyme remains an indispensable herb today, finding its place in gastronomy, medicine, cosmetics, and gardens worldwide. It is highly valued in herbal remedies and pharmaceutical formulations for its antibacterial, antifungal, and antioxidant properties derived from the richness of its essential oil, which comprises various volatile components. However, climate change poses a significant challenge today, potentially affecting the quality of thyme, particularly the extracted essential oil, along with other factors such as biotic influences and the plant's geographical distribution. Consequently, complex diversity in essential oil composition was observed, also influenced by genetic diversity within the same species, resulting in distinct chemotypes. Other factors contributing to this chemodiversity include the chosen agrotechnology and processing methods of thyme, the extraction of the essential oil, and storage conditions. In this review, we provide the latest findings on the factors contributing to the chemovariability of thyme essential oil.

Influence of Herbal Fillers Addition on Selected Properties of Silicone Subjected to Accelerated Aging

This work aims to assess the impact of the type and percentage of powdered herbs on selected properties of silicone-based composites. The matrix was an addition cross-linked platinum-cured polydimethylsiloxane. The fillers were powdered thyme and sage, which were introduced at 5, 10, and 15 wt.%. The introduced fillers differed in composition, morphology, and grain size. The grain morphology showed differences in the size and shape of the introduced fillers. The qualitative and quantitative assessment resulting from the incorporation was conducted based on tests of selected properties: density, wettability, rebound resilience, hardness, and tensile strength. The incorporation slightly affected the density and wettability of the silicone. Rebound resilience and hardness results differed depending on the filler type and fraction. However, tensile strength decreased, which may be due to the matrix's distribution of fillers and their chemical composition. Antibacterial activity evaluation against S. aureus proved the bacteriostatic properties of the composites. Accelerated aging in PBS solution further deteriorated the mechanical properties. FTIR and DSC have demonstrated the progressive aging of the materials. In addition, the results showed an overall minimal effect of fillers on the silicone chemical backbone and melting temperature. The developed materials can be used in applications that do not require high mechanical properties.

Application of the Hurdle Technology Concept to the Fresh Za'atar (Origanum syriacum) Preservation

Oregano (Origanum syriacum) is popularly called za’atar in the Middle East region. It is widely used in the Mediterranean diet as an aromatic herb. This study aimed to evaluate the preservation effect of natural additives, vacuum packaging, and refrigeration on the quality traits of fresh oregano. In total, 132 fresh oregano samples were formulated and split into 4 groups (n = 33) labeled group A (100% fresh oregano leaves, Control), group B (fresh oregano 63.2%, 15% fresh onion, 20% oil, 1.8% salt), group C (fresh oregano 61.91%, 15% fresh Allium cepa, 20% oil, 1.8% salt, 1.29% sumac), and group D (fresh oregano 59.2%, 15% fresh Allium cepa, 20% corn oil, 1.8% salt, 4% lactic acid, ultimate pH 4.4). Different quality traits such as color index (L*a*b*), microbiological analysis (total aerobic, anaerobic, and psychrotrophic bacteria and yeasts and molds), and sensory features (taste, flavor, appearance, saltiness, and overall acceptance) were assessed during the storage period (42 days) for all groups. Our study showed that the addition of lactic acid (group D) exhibited a strong preservation effect against aerobic and anaerobic bacteria. In this context, group D had significantly lower aerobic and anaerobic bacterial counts (5.12 vs. 6.7, 6, and 6.7 log (cfu/g); p < 0.05) and (4.75 vs. 6.6, 6.1, 6.77 (cfu/g); p < 0.05) than group A, B, and C; respectively. Group D exhibited significantly (p < 0.05) lower psychrotrophic bacterial count (3.6 log (cfu/g)) during the whole period of storage compared with control. Group B had a lower redness index (a*) (−3.3 vs. −1.8, −1.65, −1.23; p < 0.05) than groups A, C, and D; respectively. In conclusion, our study showed that there is a possibility of improving the preservation of oregano (Origanum syriacum) by using lactic acid and sumac combined with vacuum packaging under refrigeration conditions.

Chemical investigation on Salvia officinalis L. Affected by multiple drying techniques - The comprehensive analytical approach (HS-SPME, GC-MS, LC-MS/MS, GC-O and NMR)

In light of large scale production of Salvia officinalis L. and its complex storage and delivery chain, the efficient preservation process is required. At this moment, the most popular preservation method is drying, therefore a comprehensive experiment to evaluate the influence of multiple drying techniques on sage was conducted. Convective drying at 40, 50 and 60 °C, vacuum-microwave drying with powers 240, 360 and 480 W and combined drying consisting of convective pre-drying at 50 °C followed by vacuum-microwave finish-drying with power 360 W were applied. To evaluate the effect of particular procedures chemical analyses were performed, namely evaluation of changes in bioactive volatile constituents, odour-active compounds and various groups of non-volatile bioactive constituents of sage. The obtained results shown, that to receive the product with expected quality, it is necessary to identify the designation of the product before treatment, since particular groups of phytochemicals react differently during drying.

The Changes in Bioactive Compounds and Antioxidant Activity of Chia (Salvia hispanica L.) Herb under Storage and Different Drying Conditions: A Comparison with Other Species of Sage

Studies on herb chia (Salvia hispanica L.) are very limited. Therefore, the aim of this study was to assess how different drying methods and periods of storage affect the bioactive properties of the herb Salvia hispanica and to compare it with other species of sage (Salvia officinalis L. and Salvia sclarea L.). In fresh herbs, directly after drying (freeze-drying, natural drying, and drying at 30, 40, and 50 °C), and after storage (3, 6, and 12 months), the following analyses were performed: content of total carotenoids and total polyphenols, polyphenol profile (including 25 compounds), and antioxidant activity. Additionally, the basic chemical compositions of the herbs were analyzed. To the best of our knowledge, the content of total carotenoids and the quantitative polyphenol profile in Salvia hispanica and Salvia sclarea were evaluated for the first time. The obtained results showed that the barely investigated herb Salvia hispanica is rich in polyphenolic compounds and shows high antioxidant activity. In all the tested species, rosmarinic acid was the most abundant polyphenolic compound. The use of different drying methods allowed us to determine that freeze-drying was the most effective for preserving polyphenols and carotenoids. Long-term storage up to 12 months resulted in a gradual reduction in antioxidant activity and in the content of polyphenols and carotenoids.

Thermolabile essential oils, aromas and flavours: Degradation pathways, effect of thermal processing and alteration of sensory quality

Plant-based aroma chemicals, constituting the essential oils play a great role as the natural flavours and preservatives in the food industries. Many of these metabolites are susceptible to degradation under heat (i.e. thermolabile aroma chemicals) which may influence the organoleptic properties of the end-products e.g. essential oil, oleoresin, dry herb, tea and packaged juice. The current review identified in total 42 thermolabile aroma and/or flavour molecules belonging to monoterpenoids, sesquiterpenoids and phenolics. The probable pathway of their degradation and its promoting conditions were also described. Degradation pathways were categorized into five major classes including oxidation, C-C bond cleavage, elimination, hydrolysis and rearrangement. Numerous evidences were cited in support of the thermosensitivity of these phytochemicals under pyrolytic, thermal heating or gas chromatographic conditions. Various post-harvest processes involved in the manufacturing such as drying and distillation of the crops or thermal treatment of the food-products for storage were highlighted as the root cause of degradation. The influence of thermolabile aroma chemicals to maintain the sensory quality of the end-products such as citrus juices, floral oils and thermally cooked foods was discussed in detail. In the present article, detailed insight into the chemical and sensory aspects of thermosensitive aromas and flavours was provided, covering the period from 1990 up to 2020.

The use of bioactive properties of sage preparations to improve the storage stability of low-pressure mechanically separated meat from chickens2

The aim of this study was to determine the effect of Salvia officinalis L. (sage) preparations on the storage stability of vacuum-packed low-pressure mechanically separated meat (MSM) from chickens stored at -18°C for 9 mo. Chilled low-pressure MSM coming from 4 production batches was obtained from the plant located in north-eastern Poland. All sage preparations-a water extract, ethanol extracts, and an essential oil-were prepared and added to the MSM under laboratory conditions. Five samples of low-pressure MSM were prepared that differed in terms of the type of sage preparation added: control-without addition of sage, WE-2.0% addition of water extract from sage, E40-2.0% addition of 40% (vol/vol) ethanol extract from sage, E70-2.0% addition of 70% (vol/vol) ethanol extract from sage, and EOS-0.1% addition of essential oil from sage. The MSM samples were assessed immediately after arrival into the laboratory and after 1, 2, 3, 4, 6, and 9 mo of storage. The quality changes of MSM samples were determined on the basis of the thiobarbituric acid reactive substances (TBARS) index and microbial analyses. On the basis of the TBARS index it was proved that addition of essential oil and (40% and 70% (vol/vol)) as well as water extracts of sage significantly (P < 0.05) slowed down fat oxidation processes in low-pressure MSM from chickens. The growth of mesophilic aerobic bacteria and psychrotrophic bacteria, coliforms, and Enterobacteriaceae was significantly (P < 0.05) restricted by all sage preparations tested. The most effective inhibitory effect for groups of bacteria analyzed in this study was demonstrated by sage essential oil, despite insignificant (P > 0.05) differences between the preparations. In conclusion, it was found that sage preparations are rich in bioactive compounds. Due to their antioxidant and antibacterial properties, especially sage oil and ethanol extracts may be recommended as an auxiliary factor to prolong the storage stability of frozen, vacuum-packed low-pressure MSM from chickens.

Spectroscopic Examination and Chemometric Analysis of Essential Oils Obtained from Peppermint Herb (Mentha piperita L.) and Caraway Fruit (Carum carvi L.) Subjected to Pulsed Electric Fields

In the food industry, the pulsed electric field (PEF) technique is used to support the process of extraction of various substances. The aim of this study was to analyze the effect of a number of PEF pulses applied to peppermint and caraway on both the content of essential oils (EO) and their spectroscopic properties. The examined herb species were placed in a special vessel in the working chamber of the device between two electrodes providing high voltage electric pulses. The pulses were delivered 0, 150, 250, and 350 times per a studied sample of each herb. Essential oils were then obtained by way of hydrodistillation. The infrared spectra for all samples were measured using an FTIR spectrometer in the spectral range of 3700–730 cm−1. The applied electric field of a predetermined number of pulses had no significant effect on the amount of distilled essential oil from caraway fruit, while in the case of peppermint, it caused a slight decrease in relation to the raw material not subjected to PEF exposure. It was found that the analysis of infrared spectra made it possible to compare the quality of the obtained oils with each other and to pre-determine their compositions.

Influence of Various Drying Conditions on Phytochemical Compounds and Antioxidant Activity of Carrot Peel

(1) Background: Drying is an important process in the research of bioactive compounds. The aim of this study was to identify an optimal condition to dry carrot peel. (2) Methods: In this study, various drying conditions including hot-air (50 °C and 100 °C), vacuum (50 °C and 100 °C), microwave (600 W and 1200 W) and freeze dying (−45 °C) were applied, and the phytochemical yield and antioxidant activity of carrot peel were then assessed. (3) Results: The results showed that the highest amount of phytochemical compounds was achieved by microwave drying at 1200 W, followed by microwave drying at 600 W and freeze drying at −45 °C. In contrast, hot-air drying resulted in the lowest level of phytochemical compounds. Regarding the antioxidant activity of carrot peel, microwave drying at 1200 W was an optimal condition as it possessed the best antioxidant activity whereas hot-air, vacuum and freeze drying were not effective methods for retaining antioxidant activity. (4) Conclusions: Based on the results obtained from this study, microwave drying at 1200 W is recommended to dry carrot peel for potential application in the nutraceutical, beverage and/or functional food industries.