Ottó Dóka

6603632074

Publications - 10

The Effects of Mineral Supplementation in Rapeseed Cake Diet on Thyroid Function and Meat Quality in Broiler Chickens

Tamás Tóth Hedvig Febel Mihály Kovács Rita Éva Horváth Ottó Dóka

Publication Name: Agriculture Switzerland

Publication Date: 2024-12-01

Volume: 14

Issue: 12

Page Range: Unknown

Description:

Rapeseed is a high-quality protein source; however, its quality primarily depends on the variety, origin, and processing method. This study aimed to examine the effectiveness of a mineral supplement (“Peelko”; 27% Ca, 3.5% Mg, 800 mg/kg Fe) in terms of whether it is suitable for reducing the remaining antinutritional substances in cold-pressed rapeseed cake, thereby improving the nutrient content and digestibility of rapeseed. The experiment was carried out with 600 Ross-308 broilers divided into three feeding groups: the control diet contained extracted soybean meal, the R treatment included 10–15% cold-pressed rapeseed cake (in grower and finisher phases), and the R+ treatment consisted of the mineral supplement in addition to the cold-pressed rapeseed cake. R+ had a beneficial effect on the FCR in the grower and finisher feeding phases; moreover, it increased the weight of thyroid glands and the T3 and T4 hormone levels in the blood serum to a lesser extent than R when compared to C (p < 0.05). Diet-specific changes could be observed through the histological examination of thyroid glands, where the acini became larger when the unsupplemented cold-pressed rapeseed cake was fed (R group). Using the mineral supplement (R+ diet) decreased the acinus diameter compared to the R diet, with a similar value to that observed in control birds. The protein content in the breast and fat content in the thigh showed milder changes in R+ than R, compared to C (p < 0.05). The relative ratio of n-6 and n-3 fatty acids narrowed in both R and R+ meat samples compared to C (p < 0.05). R+ may have a more favorable effect on oxidation processes according to the better MDA values in fresh meat (p < 0.001) and samples after 1–2 months of storage (p < 0.05) than R when compared with C. The negative modifications in the color parameters (L*, a*, and b*) and the organoleptic properties of the meat were less significant with R+ than R, compared to the control (p < 0.05). According to the results of this study, the R+ treatment was able to reduce the antinutritional effects of rapeseed, as evident from the properties of the resulting animal products.

Open Access: Yes

DOI: 10.3390/agriculture14122333

Quantification of total polyphenol content in wine lees by conventional optical and photoacoustic spectroscopy

Zsolt Zsófi György Végvári G. Simon G. Ficzek Szabolcs Villangó Ottó Dóka

Publication Name: Oeno One

Publication Date: 2023-03-30

Volume: 57

Issue: 2

Page Range: 257-264

Description:

The He-Ne laser (632.8 nm) and photoacoustic spectroscopy (PAS), a variant of the photothermal methods, were combined with the Folin-Ciocalteu colorimetry method to determine total phenolics in wine lees. Utilising this method we found that the total polyphenol content of the nine selected wine lees varied from 1305 to 3907 mg/L. The gallic acid equivalent was determined by means of spectrophotometry using 765 nm as the analytical wavelength. The original Folin-Ciocalteu colorimetry assay was modified for the PAS measurements. Since the PAS does not need dilution, the filtration steps and the Folin-Ciocalteu reagent were used directly on the wine lees samples. Using the original colour reaction process and the modified reaction, the PAS showed linear behaviour between the total polyphenol content and the PA signal; the results of which gave determination coefficients of 0.9946 and 0.9936, while the limit of detection was 232.6 mg/L in both cases.

Open Access: Yes

DOI: 10.20870/oeno-one.2023.57.2.7178

Effect of protein content on the thermal effusivity of foods

G. Szafner Nóra Gombköto Ottó Dóka

Publication Name: Acta Alimentaria

Publication Date: 2021-12-31

Volume: 50

Issue: 4

Page Range: 475-483

Description:

The availability of thermophysical properties of both foods and their constituents is of considerable importance to the industry. The thermal effusivity is one of the less explored thermophysical parameters. It governs the penetration of heat into materials and is defined as the square root of the product of thermal conductivity of the material, volume-specific heat capacity, and density. This paper describes the application of a relatively new inverse photopyroelectric method (IPPE) to determine thermal effusivity of dehydrated whey protein isolate and egg white powder versus protein content. In both cases the effusivity values decreased linearly with increasing protein content. One percent increase in protein content of whey protein isolate and egg white lead to 6.5 and 7.2 Ws1/2 m-2 K-1 decrease in effusivity values, respectively.

Open Access: Yes

DOI: 10.1556/066.2021.00042

HPLC and direct photothermal techniques for quantification of β-carotene in sea buckthorn juices

I. Jócsák M. Máté György Végvári G. Simon G. Ficzek D. Székely Ottó Dóka

Publication Name: European Journal of Horticultural Science

Publication Date: 2021-01-01

Volume: 86

Issue: 5

Page Range: 493-498

Description:

The analytical performance of the proposed laser-based photoacoustic spectroscopy (LBPAS) and optothermal window (OW) method for quantification of β-carotene content in sea buckthorn juices is compared to that of the conventional high-performance liquid chromatography (HPLC). Both photothermal techniques (laser-based photoacoustic spectroscopy (LBPAS) and optothermal window (OW)) are direct methods that unlike HPLC obviate the need for the extraction of the analyte. The outcome of the study leads to the conclusion that LBPAS and OW are both suitable for quick screening of ß-carotene in sea buckthorn juices. The β-carotene content of the samples changed due to the added sea buckthorn pomace and storage time. The correlation between the two methods and HPLC is linear with R2=0.9897 for LBPAS and R2=0.9928 for OW, respectively. Both methods are capable of the rapid and non-destructive determination of β-carotene in sea buckthorn juices without a need for sample pre-treatment.

Open Access: Yes

DOI: 10.17660/EJHS.2021/86.5.5

Carotenoid quantification of Cucurbita spp. by spectrophotometry, high-performance liquid chromatography and photoacoustics

I. Jócsák György Végvári Noémi Kappel Ottó Dóka

Publication Name: Acta Scientiarum Polonorum Technologia Alimentaria

Publication Date: 2019-01-01

Volume: 18

Issue: 2

Page Range: 143-152

Description:

Background. Photoacoustic spectroscopy (PAS) is a tool for the rapid and non-destructive identification of materials even without contact. In recent years, there have been several works concerning the applicability of PAS in food analytical measurements. The intention of this work is to identify whether there is a correlation between total carotenoid and the β-carotene content of pumpkin and squash measured by high-performance liquid chromatography (HPLC), spectrophotometry (SP) and PAS. Material and methods. 'Crown prince F1', 'Veenas F1', 'Atlas F1' and 'Apollo F1' (SAKATA) were used as experimental materials. The samples were measured in a fresh state and in a lyophilised condition with HPLC, SP and PAS. Results. The results of SP show that total carotene content varies according to the species and variety. Lyophilisation resulted in lower, although varying carotene content compared to the raw form. Typical PA spectra of pumpkins were determined (300-550 nm), normalized to the carbon black powder. At 17 Hz the amplitude and carotene content shows direct proportionality in the range investigated. Photoacoustic (PA) signal and carotenoid content of pumpkin samples gave a linear correlation (R2 = 0.9821). Conclusion. The measurement of PA spectra gives reliable information about the total carotene content of pumpkin and squash samples. These findings may allow the use of PAS as a fast tool for the carotenoid determination in squashes and give the possibility of instead for the results to be used for the evaluation of squash varieties currently used for industrial processing in functional food development.

Open Access: Yes

DOI: 10.17306/J.AFS.2019.0639

Application of laser-based photoacoustic spectroscopy and colorimetry for quantification of anthocyanin in hard boiled candy

Mihály Kovács Zsolt Ajtony Ottó Dóka Dane Bicanic

Publication Name: Microchemical Journal

Publication Date: 2017-11-01

Volume: 135

Issue: Unknown

Page Range: 100-104

Description:

The analytical performance of the newly proposed laser-based photoacoustic spectroscopy (LPAS) and colorimetric method for quantification of anthocyanin (E163) in commercially available hard boiled candies are compared to that of the spectrophotometry (SP). Both LPAS and colorimetry are direct methods that unlike SP do not require the extraction of the analyte or some additional sample treatment. Results indicate that LPAS and colorimetry are both suitable for quickly screening content of anthocyanin in hard boiled candies. The correlation between the two methods and spectrophotometry is linear with R2 = 0.9989 for LPAS and R2 = 0.9570 for colorimetry.

Open Access: Yes

DOI: 10.1016/j.microc.2017.08.013

Rutin in buckwheat grain meal determined by UV photoacoustic spectroscopy and HPLC

György Végvári Andrea Brunori Ottó Dóka Dane Bicanic Rezso Schmidt

Publication Name: Nova Biotechnologica Et Chimica

Publication Date: 2017-06-27

Volume: 16

Issue: 1

Page Range: 61-67

Description:

A relatively novel approach for easy and quick determination of rutin in buckwheat grain is suggested. The rutin content of the grain in seven common buckwheat (Fagopyrum esculentum) and six Tartary buckwheat (Fagopyrum tataricum) varieties was investigated by means of UV photoacoustic spectroscopy and HPLC as reference method. The lowest content was found in 'Botan' and 'Bamby' varieties, while the highest values were obtained in the variety 'Emka'. Rutin content in grain of all Tartary buckwheat varieties was two orders of magnitude higher than in the other varieties. Rutin content in F. esculentum ranges between 9 and 36 mg/100 g dry weight as compared to 921 to 2 132 mg/100 g dry weight in F. tataricum. The UV photoacoustic spectroscopy data show rather good correlations of R2=0.977 and R2=0.980 with values obtained by HPLC data for all measured samples. Therefore, UV photoacoustic spectroscopy can be a cheap and quick method for determining rutin content in buckwheat grain.

Open Access: Yes

DOI: 10.1515/nbec-2017-0009

Determination of two color agents in hard boiled candy by laser-based photoacoustic spectroscopy and colorimetry

Mihály Kovács David Richfield Ottó Dóka

Publication Name: Carpathian Journal of Food Science and Technology

Publication Date: 2019-01-01

Volume: 11

Issue: 4

Page Range: 126-132

Description:

Determination of color agents was performed by laser-based photoacoustic spectroscopy (LPAS) and colorimetry in hard boiled candies containing two different colorants (anthocyanin and beta carotene). LPAS and colorimetry are fast and direct methods which do not require any chemicals or complicated sample preparation such as extraction. Both LPAS and colorimetry were shown to be suitable for quick determination of anthocyanin and beta carotene content in hard boiled candies. The determination of anthocyanin content in colored hard-boiled candies is possible by LPAS at 532 nm or by colorimetry using ΔE*, while the beta carotene content can be measured by LPAS at 473 nm or by colorimetry using the Hue color index.

Open Access: Yes

DOI: 10.34302/2019.11.4.11

Application of optical spectroscopy techniques in fruit juice analysis: A review

Pavithra Hemachandra Ottó Dóka

Publication Name: Progress in Agricultural Engineering Sciences

Publication Date: 2025-12-01

Volume: 21

Issue: 1

Page Range: 39-60

Description:

Fruit juices are widely consumed for their nutritional value and sensory appeal, but concerns regarding quality, adulteration and authenticity necessitate reliable, rapid and non-destructive analytical techniques. This review explores applications of UV-Visible spectroscopy (UV-Vis), infrared spectroscopy, fluorescence spectroscopy and Raman spectroscopy in fruit juice analysis. Literature was retrieved from Scopus, Web of Science and Google Scholar using predefined search terms. The working principles, instrumentation, and performance of these techniques are discussed, UV-Vis detection of pomegranate juice adulteration (R2 up to 0.99), NIR prediction of Ca (RPD = 3.92), and ATR-FTIR sugar quantification (R2 > 0.99). Applications include detecting and quantifying nutrients, adulterants, toxic elements and verifying quality attributes such as color, phenolic content and acidity. Integration with chemometrics and Artificial Intelligence (AI) enhances accuracy and predictive power, while miniaturization and multimodal approaches enable real-time, in-field monitoring. Despite challenges such as matrix effects and calibration complexity, optical spectroscopy shows strong potential for ensuring fruit juice safety, quality and authenticity.

Open Access: Yes

DOI: 10.1556/446.2025.00219

Classification of flours based on color measurements and evaluation using multivariate mathematical methods

Ferenc Kajdi András Horváth Ottó Dóka

Publication Name: Heliyon

Publication Date: 2025-11-01

Volume: 11

Issue: 16

Page Range: Unknown

Description:

The quality of flour and its composition are essential questions for bakeries and customers. In this study, 44 different cereals were studied with colorimetry. The color indices CIE L∗, a∗ and b∗ along with the reflection spectra were measured and evaluated using multivariate statistical methods. Principal Component Analysis (PCA) and Non-Negative Matrix Factorization (NMF) were applied to characterize reflection functions and reduce the dimensionality of these data. The aim of the study was to determine whether color measurements could differentiate between whole-grain and non-whole-grain flours, and between wheat and non-wheat (triticale and rye) flours. Cluster analysis was performed on the reflection spectral data, L∗a∗b∗ coordinates, PCA coefficients, and NMF weights to identify distinct sample groups. Both dimensionality reduction methods revealed that the wheat samples studied form a four-dimensional subspace in the original multidimensional reflection spectra dataset. Furthermore, the findings confirmed that the applied methods effectively distinguish whole grain from non-whole grain flours and wheat from non-wheat flours.

Open Access: Yes

DOI: 10.1016/j.heliyon.2025.e44096