The Volatile Compound Profile of “Lumblija”, the Croatian Protected Geographical Indication Sweet Bread

Abstract

“Lumblija” is a Croatian autochthonous sweet bread which recently obtained a European Protected Geographical Indication (PGI) label. The peculiarity of “Lumblija” is the use of ingredients such as concentrated grape must, rose or herbal brandy, and various herbs and spices, mostly produced and collected in the area of the island of Korčula. To the author’s knowledge, the volatile compounds of “Lumblija” have not been investigated till now. The aim of this study was to characterise the volatile compounds responsible for the distinctive aroma of the traditional sweet bread “Lumblija”, which is widely appreciated for its unique sensory properties. Four samples of “Lumblija” were investigated. Headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry analysis (HS-SPME/GC-MS) was applied for volatile compound characterisation of “Lumblija” samples. A total of 50 volatile compounds were identified in the “Lumblija” samples. Volatile compounds belong to different chemical classes: terpenes, phenylpropanoids, alcohols, aldehydes, esters, ketones, aromatic hydrocarbons, and carboxylic acids. Among them, terpenes and phenylpropanoids were the most numerous and the most abundant volatile compounds. Most differences in the volatile compound profile of “Lumblija” samples can be attributed to some specific ingredients such as spices. The results of this study could be useful to establish a volatile compound profile of “Lumblija”, which could serve as an indicator of the authenticity and quality of this autochthonous bakery product.

1. Introduction

The significant increase in consumer demand for traditional and regionally distinctive foods in recent decades has prompted the European Union to create a legal framework to protect and promote these products. In this context, the Protected Geographical Indication (PGI) refers to a product in which at least one of the production stages takes place in a precisely defined geographical area. “Lumblija” is a Croatian autochthonous sweet bread traditionally produced on the island of Korčula. It is the 38th Croatian food product which received a European Protected Geographical Indication label, PGI [1]. According to historical data, “Lumblija” is a sweet bread traditionally prepared for the Catholic holiday All Saints’ Day in November on the island of Korčula. The story about the origin of the name “Lumblija” is connected to a sad love story between a French soldier who was a baker and a young girl from the island of Korčula. With the departure of the French army, the soldier-baker also left and at parting, he gave his beloved a sweet bread with the words “n’oublie pas”, which means “don’t forget me”. The girl heard those words as “Lumblija” so it is preserved till today. According to the product specification numerous ingredients are used in the production of “Lumblija”, most of which are produced and collected in the area of Korčula island [2]. Some of the main ingredients for making “Lumblija” are wheat flour, sugar, roasted almonds and walnuts, raisins, yeast, milk, concentrated grape must (called “Varenik”), vanilla sugar, water, sea salt, butter or lard, rose or herbal brandy, and spices such as ground cloves, coriander, citrus fruits (mostly lemon and orange peel), anise, and nutmeg. Some producers also add ground carob when preparing the dough for “Lumblija”. The art of making “Lumblija” is not only the abundance of ingredients, but also the skill of preparing the dough by optimizing all the ingredients, as well as the appropriate baking conditions. The final baked product has a round shape and a dark brown surface, usually coated with “Varenik” or brandy and covered with crystal sugar. Owing to its special ingredients, “Lumblija” is characterised by a distinctive flavour profile with nutty and fruity notes, which is why it is highly appreciated by consumers. The peculiarity of “Lumblija” is in the traditional manufacturing recipe and reputation, which have been preserved to this day. Autochthonous and traditional products are not only of the special interest for producers and consumers, but also for the scientific community in order to support and maintain the product’s quality.

According to Giannone et al. [3], only a limited number of breads have been granted protected designation of origin (PDO) status at European level, including the Italian varieties “Pane di Altamura”, “Pagnotta del Dittaino”, and “Pane Toscano”, as well as the Swedish bread “Upplandskubb”. This certification not only protects the unique geographical and traditional production characteristics of these breads but also increases their market value and consumer confidence. Bianci et al. [4] demonstrated that the characterisation of volatile compounds in PDO “Altamura” bread represents a reliable approach to assess product authenticity and prevent commercial fraud, protecting both consumers and producers. In addition, Giannone et al. [3] evaluated the physico-chemical properties and sensory profile of the durum wheat bread “Dittaino” and emphasised the importance of combining sensory analysis with chemical and physical profiling to obtain a comprehensive assessment of product quality.

To the author’s knowledge, the volatile compounds of “Lumblija” have not been investigated till now. So the aim of this work was to characterise, for the first time, the volatile compounds in the PGI sweet bread “Lumblija” obtained from several local producers from the island of Korčula using headspace solid phase microextraction coupled with gas chromatography–mass spectrometry analysis (HS-SPME/GC-MS). In previous papers [5,6,7,8], the authors proposed the HS-SPME method for the extraction of volatiles from samples. The reasons for using this technique were that it is very simple in sample preparation, rapid, and solvent-free. These results could be helpful to obtain a volatile profile of “Lumblija” which could be used to evaluate authenticity of this autochthonous bakery product [4]. This is very important, especially for protected food products, because it can be a very effective tool to prevent adulteration. According to Bianchi et al. and Yang et al. [4,9], characterisation of the food flavour profile could be considered as a chemical “fingerprint” of the product, taking into account the specifics of the product’s recipe and manufacturing process. The results of this study are in accordance with the importance of highlighting the expanding application of volatile compounds in food authentication [9].

2. Materials and Methods

2.1. Samples

In this research, four samples of the sweet bread “Lumblija” were examined (labelled A, B, C, D). All samples were obtained from local producers from the island of Korčula and all of them were prepared according to the procedure described in the publication of an application for registration of a name pursuant to Article 50(2)(a) of Regulation (EU) No 1151/2012 of the European Parliament and of the Council on quality schemes for agricultural products and foodstuffs [2]. The samples were divided into smaller portions, vacuum-sealed, and stored at 4 °C until the analysis.

2.2. Headspace Solid-Phase Microextraction

HS-SPME was carried out using a SPME fibre coated with a layer of divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS, 50/30 µm film thickness) obtained from Supelco (Supelco Inc., Bellefonte, PA, USA). Before use, the fibre was conditioned according to the manufacturer’s instructions. The isolation of headspace volatile compounds was performed as follows: 3 g of the “Lumblija” sample was chopped into smaller pieces and placed in a 15 mL glass vial sealed with PTFE/silicone septa. To allow equilibration, the sample was maintained at 60 °C for 15 min on a magnetic stirrer equipped with a temperature sensor (model MR Hei-End, Heidolph Instruments GmbH & Co. KG, Schwabach, Germany). The SPME fibre was immersed through the septa and exposed to the headspace vapours above the sample for 45 min. The fibre was then transferred to the GC injector and desorbed for 7 min at 250 °C. The HS-SPME procedure was performed using previous methodology described by Wei et al. [10] and already used in our previous research [11,12].

2.3. Gas Chromatography—Mass Spectrometry

The GC-MS analyses were conducted with an Agilent Technologies (Santa Clara, CA, USA) gas chromatograph (GC) model 8890 coupled with a mass selective detector (MSD), model 5977E. An HP-5MS capillary column (5% phenyl-methylpolysiloxane, Agilent J&W, Santa Clara, CA, USA) was used for the chromatographic separation. The oven temperature was programmed at 70 °C for 2 min and then increased from 70 to 200 °C (3 °C/min) and held at 200 °C for 15 min. The carrier gas was He (1.0 mL/min). The MSD (EI mode) was operated at 70 eV, and the mass range was 30–350 m/z. The GC conditions were developed by the researchers of the Department of Organic Chemistry of the Faculty of Chemistry and Technology of the University of Split and described in our previous publications [11,12]. The Enhanced Data Analysis software from Agilent MSD Chemstation version F.01.03.2357 was used for chromatogram data analyses. The compounds were identified by comparing their mass spectra with the spectra listed in the NIST 17 and Wiley 9 mass spectral libraries using the internal library search algorithm for the Agilent MSD Chemstation software (F.01.03.2357), and by comparing their retention indices (RI), determined relative to n-alkanes (series C₈–C₂₀, C₂₁, C₂₂, C₂₃, C₂₄, C₂₅, Fluka Chemie GmbH, Buchs, Switzerland) with the values reported in the literature [13]. The percentage composition was computed from the GC peak areas using the normalisation method, and the average component percentages were calculated from triplicate HS-SPME/GC-MS analyses.

3. Results and Discussion

The aroma profile of cereal products, mainly different kinds of breads and biscuits, has been widely investigated in recent years [7,14,15]. Most of these investigations found that the volatile aroma compounds are generated during two main steps in bread production, fermentation and baking. Considering that the production of “Lumblija” is quite similar to the production of bread (fermentation and baking of the dough), the volatiles identified in studied samples can be classified into three main groups: volatiles generated during the fermentation of the dough, volatiles from the baking process, and, finally, volatiles characteristic of some specific ingredients of product. According to Garvey et al. [15], there are more than 100 identified volatile organic compounds that are responsible for aroma and flavour perception in baked confectionery products. They belong to different chemical classes, such as terpenes, alcohols, aldehydes, esters, acids, ketones, pyrazines, furans, etc.

Fifty volatile compounds belonging to different chemical classes have been identified in four samples of “Lumblija” and classified as follows: 19 terpenes, 15 phenylpropanoids, 6 alcohols, 5 aldehydes, 2 esters, 1 ketone, 1 aromatic hydrocarbon, and 1 acid (Figure 1).

The unique sensory profile of “Lumblija”, characterised by its aromatic, nutty-fruity flavour and fragrance, is primarily due to the carefully selected ingredients, while the traditional preparation methods give it its characteristic dense and compact inner texture. These sensory attributes not only add to the authenticity of the product but also increase consumers’ enjoyment and preference and strengthen its cultural and gastronomic significance.

The volatile compounds of “Lumblija” obtained from local producers are listed in

Table 1. Volatile compounds identified in “Lumblija” samples (A–D).

RI	Volatile Compound	A Av ± SD	B Av ± SD	C Av ± SD	D Av ± SD	Odour Description *
<900	ethanol	9.53 ± 1.26	10.84 ± 0.75	22.85 ± 1.44	10.21 ± 0.17	alcoholic
<900	acetic acid	0.87 ± 0.13	0.91 ± 0.09	1.91 ± 0.13	1.16 ± 0.17	sour
<900	ethyl acetate	0.21 ± 0.02	0.21 ± 0.06	0.29 ± 0.02	0.18 ± 0.02	ethereal, fruity, sweet, green
<900	2-methylpropan-1-ol	0.31 ± 0.11	0.43 ± 0.07	0.70 ± 0.05	0.39 ± 0.10	ethereal, winey
<900	(Z)-but-2-enal	0.19 ± 0.08	0.30 ± 0.01	0.09 ± 0.00	nd	nf
<900	acetoin	0.23 ± 0.03	0.33 ± 0.03	0.75 ± 0.09	0.11 ± 0.04	pungent, sweet, creamy, buttery
<900	3-methylbutan-1-ol	0.32 ± 0.02	0.38 ± 0.03	1.49 ± 0.05	0.39 ± 0.09	sweet, green, fruity, apple, nutty
<900	2-methylbutan-1-ol	0.18 ± 0.01	0.22 ± 0.00	nd	0.20 ± 0.00	ethereal, alcoholic, fatty, greasy
<900	butane-2,3-diol	nd	nd	0.62 ± 0.11	nd	buttery, creamy, pungent, caramelly
<900	hexanal	0.16 ± 0.05	nd	nd	0.09 ± 0.00	grassy, greenish, fruity
<900	furfural	0.48 ± 0.02	0.58 ± 0.08	1.02 ± 0.05	0.48 ± 0.02	sweet, woody, bready, caramelly
<900	styrene	1.86 ± 0.36	2.15 ± 0.06	3.50 ± 0.34	1.51 ± 0.09	sweet, balsam, floral, plastic
940	α-pinene	1.84 ± 0.14	2.06 ± 0.12	2.22 ± 0.11	0.33 ± 0.01	woody, piney
969	benzaldehyde	0.24 ± 0.02	0.20 ± 0.05	0.27 ± 0.03	0.27 ± 0.01	strong, sharp, sweet, bitter almond
979	β-phellandrene	0.97 ± 0.07	3.67 ± 0.00	3.83 ± 0.13	0.30 ± 0.01	minty, terpenic
985	β-pinene	3.17 ± 0.20	2.85 ± 0.63	2.37 ± 0.08	1.75 ± 0.06	dry, woody, resinous, pine
994	β-myrcene	0.59 ± 0.07	1.27 ± 0.44	1.02 ± 0.07	0.49 ± 0.02	peppery, terpene, spicy
996	ethyl hexanoate	nd	nd	0.23 ± 0.01	0.05 ± 0.00	sweet, fruity, green banana
1007	α-phellandrene	0.13 ± 0.01	0.14 ± 0.07	0.22 ± 0.01	nd	citrus, terpenic, black pepper-like
1016	3-carene	0.13 ± 0.01	0.18 ± 0.04	0.22 ± 0.01	nd	sweet
1023	α-terpinene	nd	0.57 ± 0.02	nd	nd	citrusy, woody, terpenic
1030	p-cymene	0.57 ± 0.04	0.47 ± 0.07	0.50 ± 0.02	0.24 ± 0.01	fresh, citrus, terpene, woody, spice
1035	limonene	15.30 ± 1.40	36.07 ± 0.81	15.85 ± 0.61	26.60 ± 0.83	sweet, citrus and peely
1038	eucalyptol	0.17 ± 0.02	0.13 ± 0.00	nd	0.12 ± 0.01	eucalyptus, herbal, camphor
1065	γ-terpinene	2.35 ± 0.20	2.38 ± 0.07	2.29 ± 0.05	1.70 ± 0.06	terpenic, sweet, citrus
1091	4-carene	0.37 ± 0.07	0.46 ± 0.04	0.49 ± 0.01	nd	nf
1103	linalool	0.71 ± 0.05	0.66 ± 0.06	2.51 ± 0.09	0.21 ± 0.01	citrus, orange, floral, terpenic, rose
1105	nonanal	0.31 ± 0.07	nd	nd	nd	waxy, aldehydic, citrus
1119	2-phenylethanol	0.27 ± 0.01	0.34 ± 0.05	0.64 ± 0.09	0.25 ± 0.03	sweet, floral, fresh, bready
1166	3-phenylpropanal	0.25 ± 0.01	nd	nd	0.07 ± 0.00	nf
1189	terpinen-4-ol	2.87 ± 0.15	2.15 ± 0.49	1.81 ± 0.06	0.20 ± 0.01	pine, terpene, citrus, woody, floral
1194	α-terpineol	0.28 ± 0.02	0.20 ± 0.05	0.21 ± 0.00	0.07 ± 0.00	pine, terpene, citrus, woody, floral
1200	estragole	0.38 ± 0.06	0.12 ± 0.17	nd	0.62 ± 0.02	sweet, anise, spice, fennel
1235	3-phenylpropanol	2.57 ± 0.19	1.72 ± 0.49	1.97 ± 0.19	2.66 ± 0.27	spicy, cinnamon, fruity, floral
1248	carvone	0.69 ± 0.04	nd	nd	1.41 ± 0.03	spearmint
1277	p-anisaldehyde	nd	nd	nd	0.56 ± 0.01	sweet, vanilla, anise, coumarin
1279	(E)-cinnamaldehyde	16.88 ± 0.73	0.89 ± 0.06	0.95 ± 0.10	9.71 ± 0.32	sweet, cinnamon, clove, spicy
1292	anethole	13.04 ± 1.30	10.20 ± 1.89	10.19 ± 4.53	26.67 ± 1.17	sweet, anise, liquorice, medicinal
1293	safrole	2.01 ± 0.22	1.98 ± 0.04	2.10 ± 0.09	nd	sweet, spicy, sassafras, anise
1304	(E)-cinnamyl alcohol	1.62 ± 0.24	1.59 ± 0.00	nd	3.84 ± 0.45	cinnamon, spice, floral, green
1362	eugenol	1.41 ± 0.22	3.67 ± 1.53	5.52 ± 0.44	3.30 ± 0.12	sweet, spicy, clove, woody
1379	α-copaene	0.29 ± 0.02	0.29 ± 0.00	0.24 ± 0.00	nd	woody, spicy, honey
1392	geranyl acetate	nd	0.27 ± 0.00	0.34 ± 0.00	nd	floral, fruity, green, rose
1406	methyl eugenol	1.08 ± 0.08	1.26 ± 0.16	1.29 ± 0.08	0.16 ± 0.00	spicy, clove, blossom, woody
1422	β-caryophyllene	0.14 ± 0.10	0.53 ± 0.24	0.53 ± 0.00	0.43 ± 0.01	sweet, woody, spice, clove, dry
1432	coumarin	1.85 ± 0.54	0.80 ± 0.70	0.29 ± 0.04	1.04 ± 0.26	sweet, coumarinic
1445	cinnamyl acetate	0.91 ± 0.32	0.69 ± 0.00	nd	0.75 ± 0.04	sweet, floral, spicy, balsam, cinnamon
1500	(E)-methyl isoeugenol	0.08 ± 0.11	0.15 ± 0.10	nd	nd	spicy, clove, woody
1519	myristicin	9.93 ± 1.33	7.01 ± 1.51	4.92 ± 0.29	0.51 ± 0.04	spicy, warm, balsamic, woody
1558	elemicin	0.31 ± 0.11	0.44 ± 0.12	0.42 ± 0.02	nd	spicy, floral

RI = retention indices relative to C₉–C₂₅ alkanes; Av = average area percentage composition for 3 replicates; SD = standard deviation of the area percentages for 3 replicates; * = odour description taken from The Good Scents Company Information System and/or Flavornet online databases [16,17]; nd = not detected in sample; nf = not found in the online databases.

. Total ion chromatograms (TIC) of Lumblija samples (A–D) obtained using HS-SPME/GC-MS are shown in the Supplementary Material (Figure S1).

Among the volatiles identified in all samples, the most abundant (30.43–54.35%) and most numerous were terpenes, followed by phenylpropanoids (27.65–52.32%). This was expected, considering the specific ingredients, particularly spices such as anise, fennel, coriander, cloves, cinnamon, etc., in the “Lumblija” recipe. The observed variations in the volatile compound profiles among the analysed “Lumblija” samples are primarily due to the specific ingredients used, particularly the type, origin, and concentration of the spices. Given their potential importance for human health and nutrition, plants from the Mediterranean region are extensively used for the isolation of essential oils, which are a key component in traditional food preservation and flavouring [18]. Terpenes are essential flavouring compounds that contribute significantly to the sensory properties of various foods, while also exhibiting bioactive properties that support their importance in both culinary and medicinal contexts [19].

Among the terpenes, monoterpene hydrocarbon limonene, described as sweet, citrus, and peely, was the most abundant compound (15.30–36.07%). The high content of limonene in all samples of “Lumblija” can be attributed to the addition of grated citrus peel (lemon and orange) in the recipe of “Lumblija”. According to the literature, limonene is a typical terpene originating from the peel of citrus fruits [20]. According to Ramashia et al. [21], specific compounds contained in orange peel, particularly limonene and hesperidin, have been extensively studied for their antimicrobial and anti-inflammatory properties, demonstrating potential efficacy against a range of pathogens and contributing to the prolonged shelf life of the product. Besides limonene, other terpene compounds found in “Lumblija” which can also be attributed to the addition of citrus peel were the hydrocarbons γ-terpinene, α-pinene, β-pinene, and β-myrcene, as well as alcohol linalool. Furthermore, all samples had a relatively high content of phenylpropanoid anethole (10.19–26.67%), which can be explained by the addition of anise and fennel. According to the results of Sharafan et al. [22], trans-anethole is the dominant component of the essential oil obtained from the fruits of Illicium verum (star anise) but can also be obtained from the seeds of Pimpinella anisum (anise) and Foeniculum vulgare (fennel), and is characterised by a sweet and herbal aroma. Anise is a very popular spice among the residents of the island of Korčula. They use it for various purposes, such as making tea, cookies, and the traditional herbal liqueur named “Anižeta”. Díaz-Maroto et al. [23] found that trans-anethole was the main volatile in wild fennel species (Foeniculum vulgare Mill.). Besides trans-anethole, volatiles characteristic of various fennel species are also the terpenes α- and β-pinene, β-myrcene, α- and β-phellandrene and the phenylpropanoid estragole, all of which were identified in “Lumblija” samples. Furthermore, in addition to the phenylpropanoids anethole and estragole, other phenylpropanoids, especially (E)-cinnamaldehyde (0.89–16.88%), myristicin (0.51–9.93%), and eugenol (1.41–5.52%) were quantitatively important constituents in all “Lumblija” samples. As for (E)-cinnamaldehyde, it probably originates from ground cinnamon bark, the spice which is a common ingredient in various cakes and cookies, including “Lumblija”. The content of (E)-cinnamaldehyde was significantly higher in two “Lumblija” samples (9.71 and 16.88% vs. 0.89 and 0.95%), indicating the use of different amounts of cinnamon in the recipe. It is known that cinnamaldehyde is the main volatile compound in cinnamon essential oil [24]. Volatiles such as eugenol (1.41–5.52%) and β-caryophyllene (0.14–0.53%) were identified in all samples; according to Gaspar et al. [25], these volatiles are the main components in different types of clove products. Ground cloves are also common ingredients of “Lumblija”. Spices such as cinnamon and cloves are rich in eugenol, a compound that not only contributes to their characteristic flavour but also enhances the sensory profile of baked goods and savoury dishes [19]. Another spice used in the preparation of “Lumblija” is nutmeg. According to Rahardiyan et al. [26], nutmeg is used as a spice in several European countries, but in small quantities. The distinct aroma of nutmeg essential oil is mainly caused by the phenylpropanoid compounds such as myristicin, safrole, and methyl eugenol. So the origin of these volatiles, which were identified in all “Lumblija” samples, can be attributed to the use of nutmeg in the recipe. It is well-known that essential oils contain bioactive compounds, especially terpenes, which have a wide range of biological activities. In addition to their health benefits, essential oils are also promising as natural preservatives in the food industry [27]. In addition, the study by Gavahian et al. [28] states that different types of essential oils can inhibit the growth of harmful microorganisms in bakery products, resulting in a product with a longer shelf life and increased safety.

The alcohols identified in all “Lumblija” samples were ethanol, 2-methylpropan-1-ol, 3-methylbutan-1-ol, and 2-phenylethanol. 2-Methylbutan-1-ol was identified in three samples and butane-2,3-diole in only one sample of “Lumblija”. Among them, ethanol was predominant in all samples (9.53–22.85%). These ethanol contents can be associated with both the fermentation of the dough [3] and the addition of herbal brandy, most often rose brandy. Furthermore, the formation of 3-methylbutan-1-ol and 2-methylbutan-1-ol probably occurred during fermentation from flour amino acids (leucine and isoleucine, respectively) via the Ehrlich pathway in yeast cells [29]. 3-Methylbutan-1-ol is characterised by an odour described as banana-like, fruity, and almond-like [30] and gives a distinctive malty flavour that significantly influences the overall sensory profile of the product [3]. 2-Phenylethanol was also identified in all examined samples. 2-Phenylethanol is characterised by sweet, floral, fresh, and bready aromas. According to De Luca et al. [29], this alcohol is positively correlated with the flavour of wheat crumb and probably originates from the fermentation of the amino acid phenylalanine. Another possible source of 2-phenylethanol may be related to the addition of rose brandy as an ingredient in the recipe of “Lumblija” mentioned above. 2-Phenylethanol is common constituent of rose essential oil [31].

Of the five aldehydes detected in the “Lumblija” samples, only two, furfural and benzaldehyde, were identified in all samples, but in relatively small amounts. Benzaldehyde is likely derived from the degradation of aromatic amino acids according to Aponte et al. [32]. The presence of benzaldehyde can also be attributed to the addition of almonds, as they are a regular ingredient in “Lumblija”. According to the results of Xiao et al. [33], benzaldehyde was the predominant volatile compound in raw almonds. Furfural, another aldehyde found in all “Lumblija” samples, is likely to have originated from the two main types of reactions that occur during baking: the Maillard reaction and the caramelisation of sugars [15,29]. According to the recipe, the sugar sucrose is one of the main ingredients in the preparation of “Lumblija”. It is well known that thermally driven reactions, the Maillard reaction and Strecker degradation, are important sources of volatile organic compounds in heat-treated products, such as bakery products. One of such compounds usually found in bakery products like cakes, breads, and biscuits is furfural [6,34]. Furfural is a heterocyclic compound, an aldehydic derivative of furan, and known to be an odour-impacting compound. Furfural is one of the most important volatile compounds produced in the Maillard reaction and is known for its characteristic sweet, almond-like flavour [19]. Schieberle and Grosch [35] reported furfural as the most important caramel-like odorant of wheat bread crust. Another possible source of furfural is the addition of the concentrated unfermented grape juice called “Varenik”, which is traditionally produced and used in this part of Croatia. According to Ortu et al. [36], similar product called “Sapa” syrup is produced in different Italian regions and used as a sweetener of different kinds of food products like cheese and ice cream, or to prepare local bakery products.

The only ketone identified in all samples of “Lumblija” was the hydroxyketone acetoin. Acetoin has a pleasant, buttery odour and has a potential influence on the aroma of alcoholic beverages. Nur Aimi et al. [37] reported that acetoin is one of the normal components of alcoholic beverages, formed during fermentation by the activity of yeasts. Considering the fact that in the production of “Lumblija”, an alcoholic beverage, rose or herbal brandy, is added, it is expected that acetoin would be found. Another possible source of acetoin can be attributed to the addition of carob powder [38].

Of the two esters detected in the samples of “Lumblija”, only ethyl acetate was detected in all samples of “Lumblija”, but in rather small amounts (0.18–0.29%). According to the literature, this ester originates from the fermentation of the dough [4], but another possible source can be attributed to the addition of rose brandy.

Acetic acid was the only organic acid found among the volatile compounds of “Lumblija” (0.87–1.91%). This compound belongs to the group of the volatile compounds generated during fermentation of the dough.

It is interesting that in all samples of “Lumblija”, the aromatic hydrocarbon styrene was detected (1.51–3.50%). Data on the presence of styrene in various foods and plants are available. Regarding its origin in food, it could be a constituent originally present in the food or a result of migration from packaging materials. A small amount of styrene was observed among volatile compounds generated during the baking of sweet potato bread [39]. The presence of styrene in traditional baked goods was also documented by Cingöz [40], who identified this compound among the volatiles in Turkish “Tokat” bread. However, relatively high levels of styrene were detected in cinnamon [41]. Cao et al. [42] reported that styrene can be formed by the biodegradation of some naturally occurring compounds with structural similarities to styrene, and its presence was previously detected in cinnamon. In addition, the authors identified styrene in roasted nuts, including walnuts, and suggested further investigation into its possible formation during roasting. As roasted walnuts are a standard ingredient in the traditional “Lumblija” recipe, this observation should be considered in the context of their volatile profile. In their study, Tang et al. [43] reported that styrene in food mainly originates from migration from polymer packaging materials.

4. Conclusions

In this study, the volatile organic compounds of the Croatian traditional PGI sweet bread “Lumblija” were characterised for the first time using the HS-SPME/GC-MS technique. There were some differences in the volatile compound profiles among the investigated samples. In general, however, terpenes and phenylpropanoids were the most characteristic volatile compounds families in these “Lumblija” samples. Terpenes and phenylpropanoids were the most numerous and the most abundant volatile compounds in all samples. Most of the differences in volatile profiles can be ascribed to the specific ingredients, such as spices, in the “Lumblija” recipe, as the terpenes and phenylpropanoids originated from them. On the other hand, the volatile compounds generated during fermentation of the dough and baking process were very similar in all samples, indicating that fermentation and baking modes were quite similar. In summary, the results of this study show the importance of conducting further research, such as analysing more samples from different producers and investigating the relationship between the identified volatile compounds and the sensory attributes, in order to gain a comprehensive understanding of the aroma profile of this rare traditional product. As most of the volatiles detected are terpenes and phenylpropanoids, the main components of the spices used, future studies should also investigate their potential bioactivity. This broader perspective could provide additional value in quality assessment and support the preservation and valorisation of the local gastronomic heritage.