Janusz Wojtczak

Dr. Janusz Wojtczak

orcid

Research Focus & Metrics

Academic Career Length

12Years (2015-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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31 March 2024 in Molecules
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ABAgnieszka Bilska
Agnieszka Bilska
Joanna Kobus-CisowskaJoanna Kobus-Cisowska
Joanna Kobus-Cisowska
JWJanusz Wojtczak
Janusz Wojtczak
RKRyszard Kowalski
Ryszard Kowalski
EKEwelina Kaczmarek
Ewelina Kaczmarek
The aim of this study was to evaluate the effect of hop extracts on changes in the primary and secondary fat oxidation products, physicochemical properties, and microbiological quality of pâté-type offal sausages obtained through the partial replacement of animal fat with vegetable fat. This study demonstrated that the extraction efficiency varied among hop cone varieties, with the highest efficiency observed for the Lubelski variety and the lowest for the Magnum variety. The phenolic compound content was higher in the Magnum cones (2.74 ± 0.11 mg/g dry matter) compared to the Lubelska cones (2.27 ± 0.05 mg/g of product). Additionally, the DPPH radical scavenging activity was greater in the extract from the Magnum cones (4.21 ± 0.09 mg TE/g d.w.) than in the extract from the Lublelski cones (3.87 ± 0.05 mg TE/ g d.w.). Similarly, the extracts from the Lubelski cones exhibited a higher antiradical activity against the ABTS radical compared to the extract from Magnum cones. Throughout storage, a significant increase in the pH value was observed in the control sample and in the samples with a 20% replacement of animal fat with rapeseed oil and Magnum hop extract. However, the addition of Lubelski hop extract resulted in a decrease in the pH value during the 15-day storage period. The samples with a 20% replacement of animal fat with rapeseed oil and 0.1% Lubelski hop extract showed the least changes in water activity during storage. The samples with a 20% replacement of animal fat with rapeseed oil and the addition of 0.2% Lubelski hop extract had the lowest peroxide value and TBARS index throughout the storage period. The addition of hop extract inhibited the growth of the total number of microorganisms in the tested sausages. In the samples with a 20% replacement of animal fat with rapeseed oil, the content of aerobic microorganisms, compared to the control sample, was statistically significantly lower.

2 October 2020 in Animals
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GCGrażyna Czyżak-Runowska
Grażyna Czyżak-Runowska
JWJacek Wojtowski
Jacek Wojtowski
DGDanuta Gogół
Danuta Gogół
JWJanusz Wojtczak
Janusz Wojtczak
ESEwa Skrzypczak
Ewa Skrzypczak
DSDaniel Stanislawski
Daniel Stanislawski
The aim of this study was to compare the rheological and physicochemical parameters, as well as the organoleptic properties, of soft rennet cheese made from whole and skimmed milk in different seasons on a traditional family farm. We analyzed milk from twenty Polish Holstein–Friesian cows for basic composition, number of somatic cells, acidity, and color in terms of the Comission Internationale de l’Eclairage (CIE) lightness*redness*yellowness (L*a*b*) system, and 24 cheeses in terms of texture, acidity, color in terms of the CIE L*a*b* system, and organoleptic parameters in summer and winter. We determined the effects of the season and the fat content of milk on the pH, titratable acidity, color, firmness, and stickiness of the cheese. Cheeses from summer milk showed greater acidification than those from winter milk (p ≤ 0.05). Skimmed milk cheeses from both seasons showed increased firmness and stickiness, and worse organoleptic characteristics, particularly in taste and consistency, than whole milk cheeses (p ≤ 0.05). The highest level of yellow (b*) was found in whole milk summer cheeses; those produced in winter were 16% less yellow. Milk from traditional family farms is a valuable raw ingredient for the production of soft, unripe rennet cheese. However, the variability of organoleptic characteristics related to the season should be taken into account in cheese production. Skimmed cheese can serve as an alternative to full-fat cheese, especially for people looking for low-fat products, regardless of the time of year.

1 March 2015 in Asian-Australasian Journal of Animal Sciences
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GCGrażyna Czyżak-Runowska
Grażyna Czyżak-Runowska
JWJanusz Wojtczak
Janusz Wojtczak
AŁAndrzej Łyczyński
Andrzej Łyczyński
JWJacek Wojtowski
Jacek Wojtowski
Maria Markiewicz-KęszyckaMaria Markiewicz-Kęszycka
Maria Markiewicz-Kęszycka
MBMarek Babicz
Marek Babicz
RFN pH45′ >5.8; EC90′ <8 mS/cm; EC24h <8 mS/cm

12 March 2021 in Acta Scientiarum Polonorum Zootechnica
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GCGrażyna Czyżak-Runowska
Grażyna Czyżak-Runowska
JWJacek Wojtowski
Jacek Wojtowski
SBSylwia Bielińska-Nowak
Sylwia Bielińska-Nowak
JWJanusz Wojtczak
Janusz Wojtczak
Maria Markiewicz-KęszyckaMaria Markiewicz-Kęszycka
Maria Markiewicz-Kęszycka
This research aimed to determine the hygienic quality, physicochemical properties and technological suitability of milk obtained in an extensive, small family farm in western Poland in the spring-summer (grazing) and autumn-winter (indoor) seasons. The farm was operated in the traditional manner where animals spend 7/24 on the pasture in the spring-summer season. The study was performed on forty-eight samples of bulk tank milk collected once a week over one year from 17 cows of the old local Polish black and white lowland breed. Milk was tested for somatic cell count, total bacterial count, basic composition, density, vitamin C content, rennet coagulation time, pH and colour in the CIE L*a*b* system. In the autumn-winter season, a higher somatic cell count, higher protein, fat and lactose levels, longer coagulation time and lower colour parameter a* values were found compared with the spring-summer period. However, no differences as regards the colour parameters L* and b* and vitamin C content were observed between the seasons. Highly significant negative correlations between the colour of the milk and the total bacterial count and somatic cell count were found (P ≤ 0.01). High somatic cells count in studied milk highlights that mastitis and milking hygiene are still a challenging task in small family farms.

9 July 2025 in Applied Sciences
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JWJanusz Wojtczak
Janusz Wojtczak
KSKrystyna Eleonora Szymandera-Buszka
Krystyna Eleonora Szymandera-Buszka
Joanna Kobus-CisowskaJoanna Kobus-Cisowska
Joanna Kobus-Cisowska
KSKinga Stuper-Szablewska
Kinga Stuper-Szablewska
Jarosław JakubowiczJarosław Jakubowicz
Jarosław Jakubowicz
Maciej JarzębskiMaciej Jarzębski
Maciej Jarzębski
There is a high demand for the development of new carriers for pharmaceutical forms for human, veterinary, and animal-feeding use. One of the solutions might be bioactive compound-loading pellets for animal forage. The aim of the work was to assess the physical and sensory properties of forage with the addition of onion peel and off-spec onions as a source of quercetin. The feed was prepared using an expanding process (thermal–mechanical expanding process). Quercetin content was evaluated in raw onion and in final-product feed mixture samples (before and after expanding, and pelleting). The obtained feed was subjected to sensory analysis, testing for expanded pellet uniformity, water absorption index (WAI), the angle of a slide, and antioxidant activity. The results confirmed a high recovery of the quercetin after the expanding process (approximately 80%), and a significantly reduced intensity of onion odor, which was confirmed compared to the non-expanded onion, which is beneficial. Furthermore, digital and optical microscopy were applied for structure analysis. Microscopic imaging results confirmed that the onion structures were visible in the whole length of feed material and analyzed cross-sections. The results can be an introduction to further research on developing products that use the expanding and pelleting process to exploit the peel and off-spec onions, as well as other waste raw materials.

4 June 2024 in Nutrients
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SBSzymon Byczkiewicz
Szymon Byczkiewicz
Dominik SzwajgierDominik Szwajgier
Dominik Szwajgier
EBEwa Baranowska-Wójcik
Ewa Baranowska-Wójcik
ATAleksandra Telichowska
Aleksandra Telichowska
KSKrystyna Eleonora Szymandera-Buszka
Krystyna Eleonora Szymandera-Buszka
Joanna Kobus-CisowskaJoanna Kobus-Cisowska
Joanna Kobus-Cisowska
In the present study, the effect of the addition of quince and collagen type I and III to dessert chocolate on its functional properties was determined. The study evaluated the antioxidant potential of the tested formulations using the FRAP method and the linoleic acid oxidation test and beta-carotene bleaching test. The tested samples were also evaluated for inhibitory activity against enzymes important in preventive health (inflammation and neurodegenerative disorders) namely: AChE, BChE, GR, GPx, COX, and SOD. The addition of quince and collagen to the chocolate samples resulted in higher activity compared to the control sample, as indicated by the FRAP test. The experiment highlighted the impact of including quince fruit on the antioxidant activity of the chocolate samples. Interestingly, merely increasing the quince fruit amount did not consistently enhance antioxidant potential. Specifically, chocolate samples with a lower proportion of quince fruit (2 g/100 g) exhibited greater antioxidant activity when supplemented with collagen I. Conversely, in samples with higher quince percentages (3 g and 4 g), those enriched with collagen III showed higher antioxidant activity. Similar correlations were observed in the linoleic acid oxidation test. Notably, samples containing 3 g and 4 g of quince and type III collagen demonstrated statistically similar highest antioxidant properties. Regardless of the collagen type used, there was no observed increase in activity towards the tested enzymes for samples with the lowest percentage of quince fruit. Both collagen types exhibited the highest activity in the inhibition assay against acetylcholinesterase and butyrylcholinesterase when combined with 3 g and 4 g of quince. Overall, the experimental incorporation of both fruit and collagen enhanced the chocolates’ activity. Similarly to the antioxidant activity findings, chocolates with lower quince fruit quantities showed increased activity when supplemented with collagen III, while those with higher quince content (3 g and 4 g) displayed higher activity with collagen I. Bitter chocolate by itself is an attractive food product, rich in many bioactive compounds. However, enriching it with other attractive raw materials can make its properties and taste even more attractive.