Hassaku

Scope: Hassaku fruit (juice, inner peel, outer peel); analysis by TLC and HPLC

Note: Note that these are not the bitter limonin (aglycone) itself, but glycosides whose bitterness has been weakened through glucose conjugation. This connects, as data on debittering through sugar conjugation during ripening, separately from the existing claim (compound-limonin's delayed bitterness).

Scope: Hassaku fruit (juice, inner peel, outer peel), analysis by TLC and HPLC methods.

Scope: Wakayama Prefecture product introduction webpage.

Note: The prefectural material states 『八朔に特徴的な苦味は、ナリンギンというポリフェノールの一種の成分によるもの』 (in translation: Hassaku's characteristic bitterness is due to the component naringin, a type of polyphenol) and that naringin is abundant in the joumou (inner membrane). Sections regarding claimed benefits (antioxidant, obesity prevention, hypertension prevention) are excluded as outside NIGAMI LAB's scope. As an administrative product introduction article without presentation of measured data, it is treated as contextual per the protocols of official evaluation reports.

Scope: The same page.

Scope: Fruit of hassaku and Kawano natsudaidai harvested and stored at the New Variety Development Center of the Ehime Prefecture fruit and vegetable federation (from October 1981 to June 1982). 10 fruits were divided into peel (flavedo and albedo), segment membrane, core, seeds and flesh and analyzed.

Scope: Limonin and nomilin by part (flesh, segment membrane, seeds, peel) of hassaku fruit (Ehime Prefecture), quantified with a dual-wavelength thin-layer chromatography scanner. Harvested on November 16, January 18, March 23 and May 17.

Scope: Juice of hassaku, natsumikan and Kawano natsudaidai squeezed with a reamer-type test juicer, quantified by high-performance liquid chromatography. Harvested from December 28 to May 8.

Scope: Fruit collected at about 1-month intervals from July 28 to January 17 from 2 hassaku trees aged 12 years at the attached farm of the Faculty of Agriculture, Kagoshima University (10 M-grade fruits, in 2 replicates of 5 fruits each). 40 g of flesh, 10 g of segment membrane and other parts were extracted with methylene chloride and quantified by thin-layer chromatography.

Note: This is the amount of limonoids as bitter substances, not a sensory evaluation. The author states that part of the bitterness of hassaku may depend on limonoids, and that the bitterness of nomilin is stronger than that of limonin (citing earlier studies). The limonoids in the segment membrane of natsumikan follow the same pattern of change as in hassaku, with the content said by the author to be about 2 times higher in hassaku.

Scope: Product description on the official page of Ito Farm (Wakayama Prefecture), a business-use seller of hassaku juice

Note: The same page also explains a production method in which only the flesh is gently squeezed with a bowl-shaped device, so that components from the outer and inner peel are not included in the juice. The relationship between this peel-excluding method and the source of the described slight bitterness (whether from the flesh itself or from residual peel) is not made explicit on the page.

Scope: A sensory test of hassaku juice from Wakayama Prefecture (10°Bx, reconstituted juice) and of juice in which naringin and limonoids were reduced with a synthetic adsorbent or other means.

Note: The method of the sensory test (number of panelists, procedure, rating scale) is not described in the main text. The statement that "no bitterness was perceived at naringin of 50 mg% or less" is for juice treated with an adsorbent, in which the limonoids were also reduced at the same time. The author states that the limonoid threshold changes with sugar content and acid content.

Scope: A test with reconstituted juice, made by diluting to 10°Bx a concentrate that had been made from Wakayama Prefecture hassaku squeezed with an in-line juicer, concentrated to 50°Bx with an APV-type plate concentrator and frozen, and with fresh juice heated at 50 to 90°C for 1 to 3 minutes. Naringin was quantified by the modified Davis method, and limonin and nomilin by high-performance liquid chromatography.

Note: This is a change in the amount of limonoids, not a change in bitterness evaluated by people. The author explains that the tasteless limonin monolactone contained in the juice becomes limonin on heating or acid-and-heat treatment, citing earlier work (Maier et al.), but this point was not confirmed in their own experiment and is to be examined further. Naringin rose from 75.0 mg% (10°Bx equivalent) in juice squeezed from the raw-material fruit to 102.2 mg% in reconstituted juice; the original treats the 40% higher naringin in the juice than in the raw-material fruit as a result similar to earlier reports (Manabe et al., Maotani et al.) that grinding the flesh moves naringin into the juice, not as an effect of heating. This is heating of juice and does not apply to pretreatment by boiling flesh or peel.

Scope: A description from 『因島柑橘史』 (in translation: "Innoshima Citrus History") by Okano Shūzō, cited by public Hiroshima material produced by the JA Hiroshima Fruit Federation.

Scope: The origin account on the same page.

Note: A record of a place-linked tradition. Documentary corroboration cannot be confirmed from the same page.