A flavor deterioration inhibitor which comprises an extract obtained by extracting Angelica keiskei, avocado, Cassia tora, Plantago asiatica L, hawthorn, fermented tea leaves or semi-fermented tea leaves with water, an organic polar solvent or a mixture thereof； and a deterioration smell inhibitor for citral or a citral-containing product. By adding the above flavor deterioration inhibitor to foods, drinks or oral care products, it is possible to inhibit the deterioration of a flavor which is easily affected by light, heat, oxygen and so on. In particular, a remarkable inhibitory effect can be achieved on deterioration due to light. By blending the above deterioration smell inhibitor with ctiral or a citral-containing product, the generation of the deterioration smell (caused by p-cresol and p-methylacetophenone) due to the passage of time or heating can be effectively inhibited.本發明係有關一種由鹼草、酪梨、決明草、車前草、山櫨子、發酵茶葉或半發酵茶葉於水或極性有機溶媒或其混合物中萃取出之萃取物所製得的香味劣化抑制劑或可抑制檸檬醛或含檸檬醛製品劣化產生臭味之用劑。本發明之香味劣化抑制劑經添加於飲食品或口腔衛生劑時，對於容易受光線、熱、氧氣等影響之物質可抑制其香味之劣化。特別是對光線具有顯著之劣化抑制效果，且因可長時間保持香味，故使用於裝填於容易受光線照射影響之透明玻璃容器、半透明塑膠容器、或透明袋等之飲食品或口腔衛生劑時，可發揮出優良之效果。又，本發明之劣化抑制劑本身之口味與味道並不會影響飲食品或口腔衛生劑原本之香味，故可廣泛地使用於各種技術領域中。又，本發明之可抑制因劣化產生之用劑使用於檸檬醛或含檸檬醛製品時，可有效地抑制經時性變化或加熱而由檸檬醛產生之劣化臭味。因此，使用本發明之抑制因劣化產生臭味之用劑時，可有效地防止含檸檬醛製品中，於製造、運送、保存期間之各階段中逐漸形成之劣化臭味，而維持新鮮感，進而可維持經濟且具有長期安定性之製品品質。
