CHANGES IN COLOR PARAMETERS OF HUMMUS ENRICHED WITH BLACK SEED (NIGELLA SATIVA) OIL DURING STORAGE
CHANGES IN COLOR PARAMETERS OF HUMMUS ENRICHED WITH BLACK SEED (NIGELLA SATIVA) OIL DURING STORAGE

Summary/Abstract: Hummus is a widely consumed plant-based spread whose popularity has continuously increased due to its favorable nutritional profile and potential for functional enrichment. In such products, visual appearance, particularly color, represents one of the first and most important quality attributes shaping consumer perception and acceptance. Changes in color may also serve as an indicator of physical and chemical processes occurring during storage, especially in semi-solid plant-based matrices such as hummus. The aim of this study was to investigate the effect of different concentrations of Nigella sativa oil (NSO) on the color characteristics and color stability of hummus during storage. Five hummus formulations were prepared, including a control sample and samples containing 4, 6, 8, and 12% NSO, expressed as a proportion of the total lipid phase. All samples were stored at 4 ± 1 °C for a period of 21 days. Color parameters L*, a*, and b* were determined using image-based color analysis, with digital image processing followed by transformation from the RGB system to the CIE Lab color model. The total color difference (ΔE) was calculated in order to assess the visual perceptibility of color changes during storage. Statistical analysis revealed that storage time had a significant effect on all color parameters (p < 0.05), whereas the effect of NSO concentration was limited, with statistically significant differences observed only for L* values. During storage, L* values initially decreased up to day 14, indicating slight darkening of the samples, followed by a pronounced increase on day 21. The a* parameter progressively shifted toward more negative values, suggesting changes in the red–green balance, while b* values showed a continuous increase, indicating enhanced yellowish tones. The ΔE values increased throughout the storage period and reached an average value of 16.11 after 21 days, corresponding to a clearly perceptible visual color change. Higher NSO concentrations were associated with increased variability and higher ΔE values, particularly in the sample containing 12% NSO. Overall, the results indicate that the color of hummus remains relatively stable during the first 2 weeks of storаge at 4 ± 1 °C, after which visually noticeable changes occur. The incorporation of Nigella sativa oil contributes to the evolution of color during storage, highlighting the importance of optimizing the level of functional lipid enrichment in order to maintain the visual quality of hummus-based products

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