Impact of Different Thermal Processing Techniques on the Phytochemical Composition, Antioxidant Capacity, and DNA-Protective Properties of Broccoli

Vegetables are usually thermally processed before consumption to improve their flavor and safety. In this work, the effect of boiling (BO), blanching (BL), steaming (ST), air-frying (AF), and pan-frying (PF)on the nutritional value and bioactivity of broccoli (<i>Brassica oleracea</i> va...

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Main Authors: Karlo Miškec, Marta Frlin, Ivana Šola
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Applied Sciences
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Online Access:https://www.mdpi.com/2076-3417/15/13/7469
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author Karlo Miškec
Marta Frlin
Ivana Šola
author_facet Karlo Miškec
Marta Frlin
Ivana Šola
author_sort Karlo Miškec
collection DOAJ
description Vegetables are usually thermally processed before consumption to improve their flavor and safety. In this work, the effect of boiling (BO), blanching (BL), steaming (ST), air-frying (AF), and pan-frying (PF)on the nutritional value and bioactivity of broccoli (<i>Brassica oleracea</i> var. <i>italica</i>) heads was investigated, including a comparative analysis of the tissue and the cooking water remaining after the treatments. Using spectrophotometric methods, AF broccoli was found to have the highest levels (<i>p</i> ≤ 0.05) of hydroxycinnamic acids (1.58 ± 0.71 mg CAE/g fw), total glucosinolates (3.76 ± 2.09 mg SinE/g fw), carotenoids (6.73 ± 2.89 mg/kg fw), and lycopene (0.91 ± 0.19 mg/kg fw). Steamed and AF broccoli had the highest total phenolics (0.72 ± 0.12 mg GAE/g fw and 0.65 ± 0.15 mg GAE/g fw, respectively; <i>p</i> ≤ 0.05). ST broccoli also had the highest levels of soluble sugars (11.04 ± 2.45 mg SucE/g fw) and total tannins (0.46 ± 0.19 mg GAE/g fw). The water remaining after cooking broccoli (BOW) had the highest total flavonoids (2.72 ± 0.59 mg QE/g fw) and antioxidant capacity (ABTS and FRAP, 57.57 ± 18.22% and 79.34 ± 3.28%, respectively; <i>p</i> ≤ 0.05). The DPPH assay showed that AF (36.12 ± 15.71%) and ST (35.48 ± 2.28%) had the strongest antioxidant potential. DNA nicking assay showed that BOW and BLW were the most effective in preserving plasmid DNA supercoiled form (99.51% and 94.81%, respectively; <i>p</i> ≤ 0.05). These results demonstrate that thermal processing significantly affects the phytochemical composition and functional properties of broccoli, with steaming and air-frying generally preserving the highest nutritional quality. Additionally, cooking water, often discarded, retains high levels of bioactive compounds and exhibits strong antioxidant and DNA-protective effects. To the best of our knowledge, this is the first study to investigate how different thermal processing techniques of vegetables influence their ability to protect plasmid DNA structure. Furthermore, this is the first study to compare the DNA-protective effects of broccoli tissue extracts and the water remaining after cooking broccoli.
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spelling doaj-art-7c00f8a67db442c9b61ebc61fe88566f2025-08-20T02:35:46ZengMDPI AGApplied Sciences2076-34172025-07-011513746910.3390/app15137469Impact of Different Thermal Processing Techniques on the Phytochemical Composition, Antioxidant Capacity, and DNA-Protective Properties of BroccoliKarlo Miškec0Marta Frlin1Ivana Šola2Department of Biology, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000 Zagreb, CroatiaDepartment of Biology, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000 Zagreb, CroatiaDepartment of Biology, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000 Zagreb, CroatiaVegetables are usually thermally processed before consumption to improve their flavor and safety. In this work, the effect of boiling (BO), blanching (BL), steaming (ST), air-frying (AF), and pan-frying (PF)on the nutritional value and bioactivity of broccoli (<i>Brassica oleracea</i> var. <i>italica</i>) heads was investigated, including a comparative analysis of the tissue and the cooking water remaining after the treatments. Using spectrophotometric methods, AF broccoli was found to have the highest levels (<i>p</i> ≤ 0.05) of hydroxycinnamic acids (1.58 ± 0.71 mg CAE/g fw), total glucosinolates (3.76 ± 2.09 mg SinE/g fw), carotenoids (6.73 ± 2.89 mg/kg fw), and lycopene (0.91 ± 0.19 mg/kg fw). Steamed and AF broccoli had the highest total phenolics (0.72 ± 0.12 mg GAE/g fw and 0.65 ± 0.15 mg GAE/g fw, respectively; <i>p</i> ≤ 0.05). ST broccoli also had the highest levels of soluble sugars (11.04 ± 2.45 mg SucE/g fw) and total tannins (0.46 ± 0.19 mg GAE/g fw). The water remaining after cooking broccoli (BOW) had the highest total flavonoids (2.72 ± 0.59 mg QE/g fw) and antioxidant capacity (ABTS and FRAP, 57.57 ± 18.22% and 79.34 ± 3.28%, respectively; <i>p</i> ≤ 0.05). The DPPH assay showed that AF (36.12 ± 15.71%) and ST (35.48 ± 2.28%) had the strongest antioxidant potential. DNA nicking assay showed that BOW and BLW were the most effective in preserving plasmid DNA supercoiled form (99.51% and 94.81%, respectively; <i>p</i> ≤ 0.05). These results demonstrate that thermal processing significantly affects the phytochemical composition and functional properties of broccoli, with steaming and air-frying generally preserving the highest nutritional quality. Additionally, cooking water, often discarded, retains high levels of bioactive compounds and exhibits strong antioxidant and DNA-protective effects. To the best of our knowledge, this is the first study to investigate how different thermal processing techniques of vegetables influence their ability to protect plasmid DNA structure. Furthermore, this is the first study to compare the DNA-protective effects of broccoli tissue extracts and the water remaining after cooking broccoli.https://www.mdpi.com/2076-3417/15/13/7469air-frying<i>Brassicaceae</i>DNA nickingglucosinolatesheat treatmentnutritional quality
spellingShingle Karlo Miškec
Marta Frlin
Ivana Šola
Impact of Different Thermal Processing Techniques on the Phytochemical Composition, Antioxidant Capacity, and DNA-Protective Properties of Broccoli
Applied Sciences
air-frying
<i>Brassicaceae</i>
DNA nicking
glucosinolates
heat treatment
nutritional quality
title Impact of Different Thermal Processing Techniques on the Phytochemical Composition, Antioxidant Capacity, and DNA-Protective Properties of Broccoli
title_full Impact of Different Thermal Processing Techniques on the Phytochemical Composition, Antioxidant Capacity, and DNA-Protective Properties of Broccoli
title_fullStr Impact of Different Thermal Processing Techniques on the Phytochemical Composition, Antioxidant Capacity, and DNA-Protective Properties of Broccoli
title_full_unstemmed Impact of Different Thermal Processing Techniques on the Phytochemical Composition, Antioxidant Capacity, and DNA-Protective Properties of Broccoli
title_short Impact of Different Thermal Processing Techniques on the Phytochemical Composition, Antioxidant Capacity, and DNA-Protective Properties of Broccoli
title_sort impact of different thermal processing techniques on the phytochemical composition antioxidant capacity and dna protective properties of broccoli
topic air-frying
<i>Brassicaceae</i>
DNA nicking
glucosinolates
heat treatment
nutritional quality
url https://www.mdpi.com/2076-3417/15/13/7469
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AT martafrlin impactofdifferentthermalprocessingtechniquesonthephytochemicalcompositionantioxidantcapacityanddnaprotectivepropertiesofbroccoli
AT ivanasola impactofdifferentthermalprocessingtechniquesonthephytochemicalcompositionantioxidantcapacityanddnaprotectivepropertiesofbroccoli