Studies on Sensory and Phytochemical Characteristics of Poppy (Papaver somniferum L.) Varieties for Their Oil Utilisation

Katalin Gupcsó, Writing – original draft , 1, 2 Zoltán Kókai, Writing – review & editing , 3 Melinda Bálint, Writing – review & editing , 3 Szilvia Tavaszi-Sárosi, Writing – review & editing , 1 and Éva Zámboriné Németh, Writing – original draft 1, *

Katalin Gupcsó

1 Department of Medicinal and Aromatic Plants, Institute of Horticultural Sciences, MATE, Villányi Str. 35-43, H-1118 Budapest, Hungary; moc.liamg@oscpugk (K.G.); uh.etam-inu@aivlizs.isoras-izsavat (S.T.-S.)

2 Sotiva Seed Ltd., Petőfi Str. 63/A, H-4440 Tiszavasvári, Hungary

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Zoltán Kókai

3 Department of Postharvest, Supply Chain, Commerce and Sensory Science, Institute of Food Science and Technology, MATE, Villányi Str. 35-43, H-1118 Budapest, Hungary; uh.etam-inu@natloz.iakok (Z.K.); uh.etam-inu@adnilem.tnilab (M.B.)

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Melinda Bálint

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Szilvia Tavaszi-Sárosi

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Éva Zámboriné Németh

Find articles by Éva Zámboriné Németh Shun-Wan Chan, Academic Editor

2 Sotiva Seed Ltd., Petőfi Str. 63/A, H-4440 Tiszavasvári, Hungary

Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

Associated Data

GUID: 76E3E984-3B1A-462C-BFFB-F59135ADC78B

The data presented in this study are available on request from the corresponding author.

Abstract

Poppy is a significant pharmaceutical crop, but the seeds and the cold-pressed oil have a big potential as healthy foods. Breeding has mainly focused on agronomical characteristics and alkaloid content. Here, we compared the sensory values, fatty acid and headspace volatile composition of poppy oils and flours produced from different varieties. Two industrial and four culinary varieties were cultivated in our field in 2021–2022. The sensory test differentiated well among varieties. Typical poppy odour and flavour were stronger both in the oils and the flours of the blue-seed varieties compared to the white-seed ones. For most varieties, the harvest year caused no relevant differences. Linoleic, oleic, and palmitic acids were the main components both in oils and flours. Larger differences were detected in the volatiles (e.g., 2 and 3 methyl-butanal and 3 methyl-butanol γ-n-caprolactone, pentofuran), depending on genotype and year. A higher ratio of saturated fatty acids negatively influenced the flavour and odour characteristics. In the headspace volatiles, these features correlated negatively with 2-pentylfuran and hexanal. The oil content of poppy flour has a positive effect on colour, appearance, tactility and poppy flavour. Our results support a goal-oriented use of poppy genotypes for high-quality dietary products.

Keywords: Papaver somniferum, poppy oil, poppy flour, fatty acid, volatile compound, sensory profile, flavour, odour, SPME headspace

1. Introduction

Papaver somniferum is one of our oldest and most important cultivated medicinal plants due to its many medicinal and industrial food uses. Poppy is cultivated in several countries for straw, which is an important pharmaceutical raw, and for seeds and fatty oils which are used in both alimentary and industrial production processes.

This multipurpose crop has a long history of domestication and breeding, resulting in the development of several different landraces, chemotypes and cultivars adopted to various uses and climatic conditions [1].

In recent decades, the selection work of Papaver somniferum focused on three main directions: creating cultivars accumulating rather high alkaloid amounts (above 2% in capsules dry weight) for industrial utilization, selecting for low alkaloid content for culinary usage (less than 0.1% morphine) and producing cultivars for special ornamental purposes with low alkaloid contents [2]. These purposes have been varied by the time and by the different countries.

The oil extracted from poppy seeds has already been mentioned both in the Bible and the Talmud, and it is considered equivalent to sunflower and olive oil, and it is therefore recommended for use on a larger scale [1,3,4]. The primary role of dietary fats in the human body is to provide energy; moreover, they are essential building blocks of living cell membranes, precursors of certain hormones, prostaglandins, and bile acids, and they provide the medium for the absorption, transport and storage of fat-soluble vitamins and other biomolecules. For humans, the consumption of certain vegetable or fish oils can provide essential fatty acids (linoleic acid, α-linolenic acid), which, beside their antioxidant effect, perform many special tasks in the body [5]. According to animal studies, poppy seed oil may improve antioxidant protection in the hippocampus after ischemia–reperfusion brain damage [6].

The cold-pressed poppy seed oil is light yellow in color, it has a pleasant taste and smell, and it is suitable for consumption. On the other side, the reddish-brown oil obtained by hot or post-pressing is used only for industrial and technical purposes [4,7] such as a solvent of oil paints while the iodized compound lipiodol may be used in radiological diagnostics [8]. It is doubtless that the biological and nutritional value of the poppy seed is considered favorable, which is related to its chemical composition [1].

Poppy seeds contain large amounts of minerals important for the human body—calcium, magnesium, potassium, iron and also carbohydrates, vitamins (B and E), trace elements (selenium, copper), as well as fiber, flavor, and fragrance substances [9].

Poppy seeds are small and vary in color from light yellow to deep blue/black. According to the studies revealing the possible correlation between the seed color and the fatty acid content, the blue-seed-type varieties usually contain less fatty acid content than the white or other color types [10]. However, as investigations of this issue include a small spectrum of genotypes, well-established conclusions could not have been taken before.

Although a relatively large number of studies have been published about poppy oil, only a few of them have been focusing on the volatile compounds, the sensory properties of the oil and only one [11] has analyzed poppy cake as well. According to the data, volatiles were considerably influenced by pressing methods but remained widely unaffected by storage time. As an example, a long-time-stored gray poppy seed oil sample from 1868 still showed all the characteristic of gray poppy seed oil [12]. In a Turkish study, 75 different volatiles were qualified. The authors concluded that the pre-treatments applied before cold pressing had a significant effect on the sensory properties of the poppy seed oils. Among the treatments, seed roasting was identified as the best processing operation in terms of improved sensory quality of the poppy seed oils [13]. From three Slovakian (one white- and two blue-seed) poppy varieties, 23 odour-active compounds have been found, of which hexanal, hexanol, 2-pentylfuram, hexanoic acid and pentanol represented the main compounds [14]. In a recent study, from the 44 detected volatile compounds, the most abundant ones were caproic acid (1.4–148 μg g −1 ), hexanal (0.9–15.2 μg g −1 ), 1-hexanol (0.3–20.1 μg g −1 ), limonene (1.3–9.4 μg g −1 ), and 2-pentylfuran (1.0–7.8 μg g −1 ) [15].

To modify the properties of products for the best consumer satisfaction, sensory analyses can be combined with aromatic analysis and/or consumer tests. Quantitative descriptive analysis and flavour profiling are the most widely used tests for the sensory characterization of oils and to assess consumer needs [16,17]. To achieve a better understanding of the sensory quality of poppy seed oil samples, Krist and co-workers [12] evaluated them by a sensory panel and by SPME-GC-MS (solid-phase microextraction–gas chromatography–mass spectrometry). The samples included grey, white and blue poppy seeds. Oils were pressed at room temperature (20 °C), except in the case of blue seeds where they were pressed at 20 °C in one case and 60 °C in another treatment. The evaluation of the odor and flavor character was made by a sensory panel, which consisted of 10 experts. They have collected those attributes, which were the most typical to the odor and flavor of the different oil types. Grey poppy seed oil was characterized by fatty, nutty and sweet odor, while in flavor, it showed nutty, sweet and peanut aftertaste notes. White poppy seed oil had a walnut, hazelnut, peanut and green odor accompanied by walnut and green flavor. Blue poppy seed oil pressed at 20 °C was nutty, had a pea peel odor, and a fatty, peanut and full-bodied flavor. When the pressing was made at 60 °C, fatty, green and roasted odors were identified. The flavor of the sample was fatty, roasted, nutty and green. In this study, the attributes were collected, but their intensities were not measured and compared by sensory profile analysis. Thirteen poppy seeds and their oils were analyzed in another study, five of them were winter varieties, and eight ones summer varieties [15]. Altogether, 22 attributes were used for the description of seeds and oils. Four of these attributes were only applied to seed samples (homogeneity of size, coarse, crunchy, and firm), three to oils (transparency, viscous, and oily) and the rest of the descriptors for both categories (poppy-typical, nutty, fatty/oily, rancid, green, hay like, mushroom like, musty, earthy, sweet, flowery, bitter, astringent, color, and homogeneity of appearance). Intensities were measured on a 5-point scale, where 0 was undetectable and 5 intense. For some visual attributes, RAL color reference cards were provided. Sessions were performed in sensory booths, two tablespoons of seeds or 15 mL of oil was served in glasses. The green aroma was associated with three methoxypyrazines that were exclusively found in summer poppies, and the sensory panel classified samples in particular by their fatty/oily, rancid, sweet, and green characteristics.

Nowadays, health promotion and disease prevention play a key role in human nutrition; therefore, the demand for poppy varieties with a favorable oil content and fatty acid composition also seems to be growing. In the experiment presented here, we studied the organoleptic properties of poppy oils and flours to detect consumers’ preferences for these valuable nutraceuticals. We compared samples originating from different poppy varieties and vegetation years to recognize the influence of these factors on the sensory and biochemical characteristics of the products. We also evaluated the headspace volatiles and fatty oil composition of the samples to reveal the genotype-specific characteristics as well as detect the eventual correlations of sensory features with fatty oil and volatile composition.

2. Materials and Methods

2.1. Plant Material, Growth Conditions and Sampling

In this study, we examined six different varieties of poppy. The plant material contains five registered varieties (‘Albakomp’, ‘Morgana’ Korona’, ‘Orel’, Zeno Plus’) and a candidate variety (‘Snow White’) one. Among them, two were industrial cultivars and four others selected for culinary purposes. The industrial variety ‘Morgana’ is characterised by morphine as the main alkaloid component while the other one ‘Korona’ has been selected for high noscapine content; both produce blue seeds. Three of the culinary genotypes (‘Orel’, ‘Albakomp’ and ‘Snow White’) are white seeded and one (‘Zeno Plus’) is blue seeded

The poppy varieties were grown in a small plot (17 m 2 ) design in four replicates, both in 2021 and 2022 in Tiszavasvári, Hungary (GPS coordinates: latitude 47.9661886° longitude 21.4082049°). ‘Orel’ and ‘Albakomp’ were cultivated only in 2021. The soil type of the field is chernozem formed on loess which has a good humus content (2.71%) and a slightly acidic, near-neutral pH (6.42). The total monthly precipitation and average monthly temperature in 2021–2022 are shown in Figure 1 . As a result of the unfavourable cold and uneven precipitation distribution in spring, the ‘Orel’ and ‘Albakomp’ varieties were destroyed in 2022.