Fragrance retention and consumer acceptance of citronella oil-fragranced cotton sewing thread: A sensory panel study

Introduction

A pleasant fragrance is increasingly treated as a functional attribute of textiles in its own right: certain scents are believed to elicit positive emotions, reduce tension, and improve mood, and aromatherapy-based textile applications have been explored for their calming and moodregulating effects. Whatever fragrance-delivery technology is used, however, the practical value of a scented textile ultimately depends on two consumer-facing questions: how strong and long-lasting the fragrance is perceived to be through normal use and laundering, and whether wearers actually find the scent pleasant and want it built into their clothing. Citronella oil, obtained from Cymbopogon (lemongrass) species, is a natural essential oil long used in perfumery and cosmetics and best known for its insect-repellent activity, alongside reported antifungal, antimicrobial, and mood-regulating (adaptogenic/sedative) properties (Kamal et al., 2020; Nakahara et al., 2013; Tahya et al., 2022) [1,2,6] . As a volatile monoterpene-rich oil, however, citronella's fragrance and repellent activity are known to fade with time and washing once applied to a textile surface (Specos et al., 2010) [5] , so consumerfacing questions of perceived strength, durability, and acceptability are central to judging whether a citronella-based fragrance finish is practically useful, independent of its underlying mechanical or chemical performance. This paper reports a structured sensory-panel evaluation of a citronella oil-fragranced cotton sewing threadproduced by coating cotton thread with citronella oil-treated paraffin wax focusing on (i) how panellists rated fragrance intensity before washing and after successive washes; (ii) how pleasant the fragrance was perceived to be; (iii) panellists' preference for, and prior awareness of, inbuilt fragrance in clothing; and (iv) panellists' awareness of citronella's associated functional properties. The physical and morphological characterisation of the same treated thread is reported in a companion paper.

Literature Review

Citronella oil applied to cotton fabric by conventional padding has been reported to give strong initial mosquitorepellent activity that diminishes within roughly three weeks, reflecting the oil's weak binding to the fibre surface when applied without an encapsulating carrier (Specos et al., 2010) [5] . Microencapsulated citronella oil, by contrast, has been reported to sustain repellency above 90% for about three weeks (Specos et al., 2010) [5] and up to 80% after 30 industrial-type washes at higher microcapsule loadings (Reis et al., 2022) [4] , underscoring that consumer-perceived durability of a citronella finish depends heavily on the delivery method rather than on the oil itself. Reviews of essential-oil textile finishing more broadly note the trade-off between simple, low-cost application methods and the greater wash-fastness achievable with microencapsulation or similar slow-release technologies (Textile School, 2021; Verma et al., 2023) [8,9] . Consumer or sensory-panel evaluation of fragranced textiles is comparatively underreported relative to the chemical and durability testing of the finishes themselves, even though acceptance and perceived pleasantness are ultimately what determine whether such products succeed commercially. This paper addresses that gap for a citronella oil-fragranced sewing thread specifically.

Materials and Methods

Study Area, Duration, and Respondents

The study was carried out in Kanpur, Uttar Pradesh, India, at the Department of Home Science, Chandra Shekhar Azad University of Agriculture and Technology, during 2022-23. The sensory questionnaire was administered between the last week of March and the first week of April 2023. Twenty-five respondents were randomly selected from students of the College of Community Science and Agriculture to form the evaluation panel.

Preparation of the Fragranced Thread

Unfinished cotton sewing thread was coated with citronella oil-treated paraffin wax: paraffin wax was melted at 100°C, blended with 5 ml of citronella oil, moulded, and cured for 15-20 minutes; the cotton thread was then drawn through the cured, fragranced wax on a yarn winder so that its surface was coated with the fragrance-loaded wax as it passed through. Samples were packaged for evaluation before washing and after 1, 5, 10, 15, and 20 washes.

Sensory/Panel Evaluation Protocol

For each wash stage, each of the 25 panellists smelled the packaged sample from a distance of 10 cm and rated the fragrance intensity on a five-point scale: very strong, strong, mild, very mild, or worse/none. Panellists separately rated (i) whether they sensed the fragrance as pleasant, irritating, or having no effect; (ii) whether they preferred garments with an inbuilt fragrance; (iii) whether they had previously heard of fragranced sewing thread; and (iv) their agreement, on a fivepoint scale (strongly agree to strongly disagree), with five statements about citronella's propertiesfragrance, insect repellency, medicinal value, antifungal action, and mood/fatigue-lifting effect. Panel demographic data (age group, gender) were also recorded.

Statistical Analysis

Responses were analysed using percentages, weighted mean scores, and rank ordering for each wash stage and each statement. A paired t-test was used to compare the mean fragrance-retention score across washes with the mean preference score for inbuilt fragrance.

Results and Discussion

Panel Demographics

Of the 25 panellists, 60% were aged 20-25 years, 32% were aged 25-30 years, and 8% were above 30 years; 64% of the panel were female and 36% male. The freshly treated thread was rated very strong or strong by 92% of panellists, and the fragrance remained detectable as strong or mild through the fifth wash for most panellists. By the tenth wash the fragrance had shifted predominantly to mild/very mild, and by the twentieth wash most panellists (68%) rated it as worse/negligible. This progressive decline mirrors the wash-durability pattern reported for unencapsulated citronella finishes elsewhere, where fragrance and repellent activity fade within a few weeks of laundering (Specos et al., 2010) [5] , and suggests that microencapsulation or a comparable slow-release carrier (Reis et al., 2022) [4] would be needed to extend the fragrance life of the thread beyond the roughly five-to-ten-wash window observed here. Eighty per cent of respondents described the citronella fragrance as pleasant, 12% found it irritating, and 8% reported no effect, indicating broadly favourable sensory reception of the fragrance among the panel. Seventy-six per cent of respondents said they would prefer clothing with an inbuilt fragrance, while 24% would not. Just over half of respondents (56%) reported having previously heard of fragranced thread; 44% had not, suggesting the concept, while appealing once experienced, is not yet widely familiar to consumers. The fragrance property itself was rated most strongly, followed by insect repellencyconsistent with citronella's established role as a natural mosquito repellent (Verma et al., 2023; Kamal et al., 2020) [9,1] and then antifungal, medicinal, and mood-lifting properties, in that order. This ranking suggests panellists' awareness and endorsement of citronella's benefits tracked most closely with its most immediately perceptible property (fragrance) and declined for properties that are less directly experienced through casual use.

Fragrance Intensity Across Washes

Perceived Quality of the Fragrance

Preference for, and Awareness of, Inbuilt Fragrance

Awareness of Citronella's Functional Properties

Relationship Between Fragrance Retention and Preference

A paired comparison between the mean fragrance-retention score across washes (18.0, S.D. 3.6) and the mean preference score for inbuilt citronella fragrance (11.4, S.D. 8.4) was statistically significant (t = 3.599, P < 0.05). This indicates that perceived fragrance strength in the thread and stated preference for an inbuilt fragrance, while related, are measured on different scales and do not move in locksteprespondents' overall fragrance rating was considerably higher than their inbuilt-preference score, implying that strong initial fragrance alone does not fully translate into stated purchasestyle preference and that other factors (e.g., expected durability, price, or prior familiarity) likely also shape consumer preference.

Conclusion

This sensory-panel study shows that citronella oil-fragranced cotton sewing thread delivers a strong, clearly perceptible, and largely pleasant fragrance immediately after treatment and through at least five washes, with 80% of panellists rating the fragrance pleasant and 76% expressing a preference for inbuilt fragrance in clothing. However, fragrance intensity declined steadily with laundering, falling to a predominantly "worse"/very-mild rating by the twentieth wash, reflecting the volatile, surface-bound nature of citronella oil when it is not chemically bound or microencapsulated. Among citronella's associated properties, fragrance and insect repellency were most strongly recognised by respondents, followed by antifungal, medicinal, and mood-lifting effects. These findings support citronella oil-fragranced sewing thread as a consumer-acceptable, functional textile innovation, while indicating that wash durability beyond roughly ten washes is the main limitation to address. Combined with the mechanical and morphological findings reported in the companion paper, encapsulation or other slow-release carrier systems appear to be the most promising direction for extending the useful fragrance life of citronellatreated sewing thread while preserving its consumer appeal and cost advantage over more resource-intensive finishing routes.

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