## 4 Conclusions  
Heat treatment processes are usually associated with the degradation of various chemical compounds naturally occurring in fruit or vegetable raw materials, and thus with the loss of nutritious bioactive ingredients. Numerous studies confirm the negative impact of heat treatment (e.g., frying, baking, boiling, microwave, or convection drying) on the content of polyphenic compounds, natural flavors, and dyes (e.g., chlorophylls or carotenoids), vitamins or antioxidants, and thus reducing the health-promoting properties of products and their nutritional value. Long-term heat treatment of fresh garlic under high temperature and humidity, called fermentation or aging of garlic, produces black garlic, a product with completely different physicochemical, organoleptic and sensory properties compared to fresh one. As a result of the transformation of carbohydrates (Maillard reactions), phenolic and organosulfuric compounds taking place during it, not only the color of garlic changes (to dark blue-black), but also the aroma (complete lack of the typical garlic aroma), taste, texture (soft, velety, and delicate taste), and most importantly, the content of bioactive ingredients (total polyphenols, flavonoids, and phenolic acids), and antioxidant activity are increased. Our research shows a significant increase in the content of total polyphenols (12.50 \(\pm\) 0.13 mg GAE/g d.m. ), flavonoids (53.53 \(\pm\) 0.10 mg/100 g d.m. ), phenolic acids (54.97 \(\pm\) 0.11 mg/100 g d.m. ), and an increase in antioxidant activity (546.26 \(\pm\) 4.60 umol TEAC/g d.m.) in black garlic compared to fresh one (5.62 \(\pm\) 0.05 mg GAE/g d.m., 35.02 \(\pm\) 0.06 mg/100 g d.m., 38.67 \(\pm\) 0.14 mg/100 g d.m., and 273.65 \(\pm\) 1.86 umol TEAC/g d.m., respectively). Additionally, fermented black garlic from organic cultivation is characterized by a significantly higher content of bioactive ingredients (by about 20% for  
Figure 2: Similarities and differences found in the tested quality parameters in tested garlic samples. total polyphenols, 28% for flavonoids, and 37% for phenolic acids content) and a higher antioxidant potential (by about 80%) than black garlic from conventional cultivation. Therefore, the results of our research can be a valuable hint for consumers, whose nutritional awareness, interest in organic food, and care for health and the quality of meals are constantly growing. The modern food and processing industry must meet not only the requirements as to the quality and health standards of food products, but also meet the high demands of the consumers looking for food with high nutritional, dietary and health-promoting values. Therefore, comparative research on physicochemical, technological, bioactive, and health-promoting properties is important for many industries and the food market. Considering that the physicochemical and bioactive properties of black garlic, including the composition and mutual proportions of biologically active substances, depend on the origin, variety, cultivation method and, above all, on the conditions of heat treatment of the raw material (in particular temperature, humidity and fermentation time) further research is necessary to select the most optimal technological processes and conditions of their course, in order to maintain or obtain products with the best pro-health, dietary and nutritional values. Conceptualization, K.N. ; methodology, K.N., A.S. and E.H.; software, K.N. ; validation, K.N., A.S. and E.H.; formal analysis, K.N. ; investigation, K.N. ; resources, K.N. ; data curation, K.N. ; writing--original draft preparation, K.N. ; writing--review and editing, K.N. ; visualization, K.N. ; supervision, K.N. ; project administration, K.N. ; funding acquisition, K.N. All authors have read and agreed to the published version of the manuscript. This research received no external funding. This paper has been published under the support of: Institute of Human Nutrition Sciences, Warsaw University of Life Sciences (WULS). All authors declare that they have no conflict of interest.