Classification
Product TypeProcessed Food
Product FormDried
Industry PositionProcessed Food Product
Market
Dried sweet potato in Japan is most commonly sold as hoshi-imo, a traditional preserved snack made by steaming sweet potatoes and drying them. Production is strongly concentrated in Ibaraki Prefecture, with the Hitachinaka–Tokai–Naka area highlighted as a core region and a main shipping window typically from November to mid-March, while the product is consumed year-round due to shelf life. Japan is both an importer and exporter under HS 071420 (sweet potatoes, fresh or dried), with 2023 imports sourced mainly from Vietnam, China, and Indonesia and exports directed mainly to Hong Kong, China; Thailand; and Singapore. For import market access, compliance hinges on Japan’s plant quarantine requirements for plant products and the Food Sanitation Act import notification process for foods intended for sale/business use.
Market RoleDomestic producer and consumer market with two-way trade (imports and exports)
Domestic RoleTraditional preserved snack (hoshi-imo) with strong Ibaraki regional identity
Market GrowthGrowing (recent multi-year trend (qualitative))increasing product/variety diversification and consumer interest reported by producers and media
SeasonalityMain commercial shipping for Ibaraki hoshi-imo is typically concentrated in winter (November to mid-March), but finished product is available year-round due to shelf life and frozen stock practices.
Specification
Primary VarietyBeniharuka
Secondary Variety- Tamayutaka
- Izumi
- Hoshikogane
- Silksweet
- Hoshikirari
Physical Attributes- Soft to sticky/chewy texture is a common quality highlight for Beniharuka-based dried sweet potato.
- Color/appearance cues (e.g., bright yellow for some Beniharuka products) are used in marketing and consumer selection.
- A white powder may appear on some hoshi-imo over time and is described by a major producer as crystallized maltose rather than mold.
Packaging- Retail pouches (example SKUs: 60g, 63g, 100g, 125g) stored at room temperature; some labels instruct refrigeration after opening.
- Shelf-life indications vary by SKU and handling (examples: 60 days to 300 days; frozen variants exist).
Supply Chain
Value Chain- Cultivation (Apr–Oct) → harvest (Oct–Nov) → temperature-managed storage/curing to develop sweetness → steaming (60–90 min) → hot peeling → slicing → drying (sun-drying several days; some use cold-air drying) → packaging → domestic retail/export distribution
Temperature- Producers describe storing harvested sweet potatoes at controlled temperature to develop sweetness prior to steaming.
- Some hoshi-imo sold outside the main season may be produced in winter and then frozen/stored for later sale (producer example).
Atmosphere Control- Some producers describe cold-air drying as a method to achieve a moist/soft texture.
Shelf Life- Commercial SKUs list multi-month shelf life at room temperature (examples: 210–300 days) depending on packaging and moisture control.
- Frozen formats are also marketed for extended storage, with shorter stated life after defrosting (product example).
Freight IntensityMedium
Transport ModeSea
Risks
Phytosanitary HighJapan’s plant quarantine regime can block or delay entry for sweet potato plant products if phytosanitary documentation and any required additional declarations for specified quarantine pests are missing or non-compliant; sweet potato is explicitly included in Plant Protection Station requirement tables tied to quarantine pests such as Bactericera cockerelli.Confirm the exact Japan Plant Protection Station requirements for the origin and product form; obtain an official phytosanitary certificate from the exporting country’s NPPO with any required additional declarations/treatments, and ensure inspection/clearance is completed before customs permit.
Food Safety MediumFor imports intended for sale/business use, failure to submit Food Sanitation Act import notification (or inconsistencies in ingredients/additives/manufacturing method documentation) can prevent release for sale and trigger inspection, disposal, or reshipment actions.Prepare complete import-notification documentation for the MHLW quarantine station, including ingredient/additive details and manufacturing method; maintain supporting specifications/COAs aligned to Japan’s additive standards where applicable.
Regulatory Compliance MediumNon-compliant Japanese labeling for processed foods (e.g., missing required items or origin/allergen/date statements) can lead to relabeling, market withdrawal, or enforcement actions, disrupting distribution timelines.Design Japanese labels to align with Consumer Affairs Agency guidance for processed foods and verify label content against importer checklists before shipment.
Climate LowFor traditionally sun-dried hoshi-imo, drying duration and output quality are sensitive to winter weather conditions, which can affect batch consistency and shipping timing during the main season.Use validated drying controls (including cold-air drying where appropriate) and plan safety stock or frozen inventory strategies to smooth seasonal variability.
Standards- HACCP (example: Ibaraki Prefectural Food Safety Association HACCP Promotion Business Certification shown on an export-facing product listing)
- JFS-B (example: a major Ibaraki processor’s plant described as holding domestic JFS-B certification)
FAQ
When is the main shipping season for hoshi-imo (dried sweet potato) in Japan?For the major Ibaraki production area, the main shipping period is typically from November to mid-March. Even so, dried sweet potatoes are consumed year-round because they have a long shelf life.
Which regions are most associated with hoshi-imo production in Japan?Ibaraki Prefecture is the best-known production base, and government and regional materials highlight the Hitachinaka City–Tokai Village–Naka City area as a core region for traditional hoshi-imo.
What are the main processing steps to make hoshi-imo?A major producer describes the core process as harvesting and storing sweet potatoes under controlled temperature to develop sweetness, steaming for around 60–90 minutes, peeling, slicing, and then drying (often sun-drying for several days, depending on weather and variety).
Why do some dried sweet potatoes have a white powder on the surface?A major Japanese hoshi-imo producer explains that the white powder can be crystallized maltose that increases as drying progresses during storage, and it is different from mold.
What must an importer do before selling imported dried sweet potato products in Japan?For foods imported for sale or business use, Japan requires an import notification under the Food Sanitation Act to be submitted to an MHLW quarantine station, and customs clearance is tied to the quarantine station’s confirmation. Plant quarantine inspection and phytosanitary documentation may also apply for plant/plant products depending on the product form and origin.