Peppers are an essential part of cuisines worldwide, valued for their flavor and spiciness, which can range from mild to extremely hot. Spiciness is determined by the concentration of capsaicinoids such as capsaicin, dihydrocapsaicin, and nordihydrocapsaicin. To date, little research has been conducted on the influence of spiciness and its factors. This has been the reason for the following graduation research by Matthijs de Jong.
This graduation research was conducted for the company FeMix Seeds, a breeding company owned by Tom and Faye van der Heiden, which has the largest collection of commercial pepper varieties in the world. Besides peppers, virtually every type and color of pepper is for sale at this company. The main factors affecting spiciness have been studied, as well as ways to optimize them. This article discusses the findings of this research, as well as the impact of growing conditions on the spiciness of different pepper varieties.
Methods of measuring spiciness
Measuring the spiciness of peppers is a complex process that involves more than just using Wilbur Scoville's traditional method. The Scoville Organoleptic Test, developed in 1912, uses human subjects to assess spiciness by tasting a diluted pepper extract until the spiciness is no longer perceptible. While historically important, this method has significant drawbacks, such as subjectivity and variability between subjects.
The study looked at several modern measurement methods to circumvent these shortcomings and get a more accurate picture of spiciness. One important method is High-Performance Liquid Chromatography (HPLC), which separates, identifies, and quantifies chemical compounds in a sample. HPLC is highly accurate and suitable for measuring low concentrations of capsaicinoids, which is crucial for determining exact Scoville values. The advantage of HPLC is its objectivity and reproducibility, unlike the subjective Scoville test.
Besides HPLC, other methods, such as gas chromatography and spectroscopy, have also been investigated to evaluate their usefulness and accuracy. The advantages and disadvantages of these methods were weighed to identify the most effective and reliable techniques for measuring spiciness.
Influencing spiciness
The spiciness can be significantly affected by different growing conditions and techniques. One of the most crucial factors is the ripening stage of the fruit. Capsaicinoids start accumulating in the early stages of fruit development and reach their peak about 40-50 days after fruit set, roughly when the fruit starts to color. After this point, when the fruit becomes overripe, the concentration decreases, sometimes by more than 60%, highlighting the importance of proper harvesting time. The position of the fruit on the plant also plays an important role; fruits growing lower on the plant are allocated more energy and show higher Scoville values than fruits growing higher.
Abiotic stress, such as drought and salt stress, can also stimulate capsaicinoid production. Drought stress generally increases capsaicinoid levels, but too much stress can lead to lower yields due to flower failure and reduced fruit set. Salt stress has a similar effect, especially at higher salt concentrations. In addition, temperature and light play a crucial role; higher temperatures and intensity of light stimulate capsaicinoid biosynthesis. Shading strategies can also increase capsaicinoid production, depending on the variety.
Fertilization strategies are also very important. Mineral fertilization increases spiciness by altering the balance between capsaicinoid biosynthesis and the accumulation of lignin-like substances in cell walls. Organic fertilization, especially in combination with mineral fertilizer, can significantly increase capsaicinoid levels. A particularly effective strategy is the combination of phosphorus and Trichoderma, a fungus that stimulates plant growth, increases chlorophyll content, increases capsaicinoid production, and improves fruit quality.
Results from FeMix Seeds Varieties
Five pepper varieties from FeMix Seeds were used in the study: Westland red pepper, yellow chili pepper, orange chili pepper, red chili pepper, and red habanero. These varieties were grown under two different growing conditions, a pepper and tomato greenhouse, and harvested at different stages of maturity. Capsaicinoid concentrations were analyzed using High-Performance Liquid Chromatography (HPLC).
The habanero variety showed significant variations in Scoville values depending on the ripening stage. Scoville values increased by 371% from unripe to ripe but decreased by 31% from ripe to overripe and by 52.5% to extra overripe. This pattern confirms the importance of proper harvest time to achieve maximum spiciness. For yellow chili pepper, significant differences were observed between growing conditions; the Scoville value increased by 59% in the tomato greenhouse versus the pepper greenhouse. This shows the importance of growing conditions for capsaicinoid development.
The yellow and orange chili peppers showed higher Scoville values under tomato greenhouse conditions compared to the pepper greenhouse. For the yellow chili pepper, the values showed an increase of 70% and for the orange chili an increase of 54%. This indicates that certain growing conditions that involve more stress can significantly increase capsaicinoid production. The red chili pepper responded negatively to stress conditions, with lower Scoville values under these conditions, showing that not all varieties respond positively to increased stress. In contrast, the habanero variety showed consistent spiciness regardless of growing conditions, suggesting that this variety is less sensitive to variations in growing conditions.
Conclusion and follow-up studies
The study shows that growing conditions and the stage of ripening of peppers have a significant influence on their pungency. These findings are of great interest to growers striving to consistently produce chilies with specific pungency. By understanding how different factors affect capsaicinoid production, growers can optimize their cultivation methods to meet market demand. Integrating specific fertilization strategies and storage conditions further contributes to maintaining and increasing the desired pungency in chilies.
In follow-up studies, it is important to work with a larger number of samples and variables to further substantiate and refine these findings. In addition, collaboration with colleges and research institutes is essential to develop innovative methods and technologies that can help growers optimize the cultivation of spicy peppers. This collaboration can help improve the quality and consistency of chilies, benefiting both growers and consumers. Finally, Matthijs would like to thank FeMix Seeds for their support and cooperation in this research. With this knowledge, the future of pepper cultivation can be further improved and innovated.
Source: Matthijs de Jong