Characterisation of aroma-active compounds in dried Dendrobium spp. stems (Shihu) using GC-Olfactometry and a modified NIF-SNIF method

Dendrobium orchid stems (Chinese name Shihu) are becoming popular ingredients in food and drinks such as wine, teas and desserts, however, its aroma chemistry is not currently understood. Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Olfactometry (GC-O) were used to analyse two Dendrobium species. The Nasal Impact Frequency-Surface of Nasal Impact Frequency (NIF-SNIF) method was employed on thirteen untrained panellists using a newly built open-source software (“nif-simple”). An expert annotated odour descriptions and intensities of NIF-SNIF peaks. Twenty-four volatile aroma compounds were found using GC-MS, with 22 shared compounds and 17 reported for the first time. GC-O NIF-SNIF indicated nine aroma compounds were aroma-active in D. nobile and D. officinale. Five were found in both species suggesting that they are species-independent markers. Aroma-active compounds were characterised as brown, mushroom, metallic, nutty and potato aromas. Methional (NIF 83 %) and 1-octen-3-one (NIF 81 %) were most frequently detected in D. nobile and D. officinale respectively, and this study proposed aroma formation mechanisms in dried Dendrobium stems. Modified Frequencies demonstrated that NIF-SNIF is an effective GC-O method for identifying key aroma-active compounds. Understanding the flavour properties of Shihu could enhance its global appeal and encourage NIF-SNIF to be used in future studies

A flavour perspective of Tiepishihu (Dendrobium officinale) – an emerging food ingredient from popular traditional Chinese medicinal plants: a review

Many Dendrobium orchid stems are used in Traditional Chinese Medicine (TCM). The most popular and premium species is Dendrobium officinale, and its stem in TCM is called Tiepishihu. Tiepishihu has a sweet flavour and is an ingredient in Chinese tea and desserts. There is no comprehensive understanding of its flavour compounds. It is, therefore, essential to understand compounds responsible for its flavour, and how they are formed. This review assesses twelve diverse studies in Tiepishihu flavour (2013–2022). Thirty aroma compounds were compared – furfural and nonanal were identified as common compounds. Four of seven essential amino acids were taste-active, with lysine being the most potent. Pre-harvest factors such as environment impact specific aroma compounds. Post-harvest processing methods, including drying and grinding, can control Tiepishihu's flavour. Methodological consistency is a challenge, but controlling Tiepishihu's flavour could increase its commercial value as a food ingredient

Patients’ perspectives on qualitative olfactory dysfunction: thematic analysis of social media posts

Background: The impact of qualitative olfactory disorders is underestimated. Parosmia, the distorted perception of familiar odors, and phantosmia, the experience of odors in the absence of a stimulus, can arise following postinfectious anosmia, and the incidences of both have increased substantially since the outbreak of COVID-19. Objective: The aims of this study are to explore the symptoms and sequalae of postinfectious olfactory dysfunction syndrome using unstructured and unsolicited threads from social media, and to articulate the perspectives and concerns of patients affected by these debilitating olfactory disorders. Methods: A thematic analysis and content analysis of posts in the AbScent Parosmia and Phantosmia Support group on Facebook was conducted between June and December 2020. Results: In this paper, we identify a novel symptom, olfactory perseveration, which is a triggered, identifiable, and usually unpleasant olfactory percept that persists in the absence of an ongoing stimulus. We also observe fluctuations in the intensity and duration of symptoms of parosmia, phantosmia, and olfactory perseveration. In addition, we identify a group of the most common items (coffee, meat, onion, and toothpaste) that trigger distortions; however, people have difficulty describing these distortions, using words associated with disgust and revulsion. The emotional aspect of living with qualitative olfactory dysfunction was evident and highlighted the detrimental impact on mental health. Conclusions: Qualitative and unsolicited data acquired from social media has provided useful insights into the patient experience of parosmia and phantosmia, which can inform rehabilitation strategies and ongoing research into understanding the molecular triggers associated with parosmic distortions and research into patient benefit