BMP testingFruit, vegetables and their residuessingle study (2 samples)

Loquat peel and seed — BMP: 2 studies, weighted mean 250 m³ CH₄/t VS

Loquat (Eriobotrya japonica) as a substrate means peels and seeds from a single study; the hard seeds and tannins affect the rate of decomposition.

CH₄ ≈ 52 % (estimate)

Published 29 January 2025Updated 29 October 20263 min readFeedstockData Editorial Team

Photo Ivar Leidus / Wikimedia Commons, licence CC BY-SA 4.0, source file; changes: cropping

Weighted mean: 250m³ CH₄/t VS
Range: 208–292m³ CH₄/t VS
Records: 2single study (2 samples)
Publications: 1source
Temperatures: —of the test

Methane in biogas

≈51–54% CH₄

Medium methane content · ≈ 5.2 kWh/m³ of biogas

estimate from the substrate type The collected studies contain no measurement. The interval follows from the approximate composition (protein from total nitrogen (N 1.2 % DM × 6.25)) and the yields of compound groups according to FNR.

How we calculate it and what the zones mean

Rating for biogas plants

not rated — editorial rating for biogas plants

Not rated: no dry matter or volatile solids in the data. We calculate the rating when the dry matter and volatile solids of the material are known.

Editorial rating per the methodology

Add to the co-digestion calculator CSV data

BMP curves from 2 studies

Weighted mean Individual records

Dashed lines are a model curve (first-order kinetics, B(t) = B₀·(1 − e^−kt)); the end point comes from the publication. All curves are model curves.

Cumulative methane production over the test [m³ CH₄/t VS]. The thick line is the weighted mean of all records (250); dots mark the end values given in the publications. Point at the chart to read values; click a legend item to hide or show a record.

Records and sources

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Source	BMP m³ CH₄/t VS	Temperature	Sample	Curve
Zhao et al. (2016) · 1 DOI	208	—	Loquat (Eriobotrya japonica) – Seed	end point (model curve)
Zhao et al. (2016) · 2 DOI	292	—	Loquat (Eriobotrya japonica) – Peel	end point (model curve)
Weighted mean	250	arithmetic mean 250, SD 59

Typical composition

Volatile solids (VS): 95 % DM (range 91.7–98.3)
Nitrogen: 1.2 % DM
C/N ratio: 47.4

Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: BCBPD); dry matter: 0 determinations, volatile solids: 2 determinations. C/N was calculated as the ratio of C and N content (% DM) from the same source. No DM in the sources – the calculator has to ask for a value.

Sources: Zhao et al. (2016).

The composition of the raw material varies between batches — for plant calculations use an analysis of your own sample. The calculator inserts typical values automatically.

Process properties

Low confidence: the description is based on general characteristics of the substrate group, not on studies of this material. Treat it as a hint to be verified.

No published process studies

The literature we use does not describe the advantages or drawbacks of digesting this substrate beyond the BMP test results. Below are process characteristics assigned on the basis of the type of material — an editorial classification, not a study result.

fibrous: lignocellulose, long fibres → floating layer, harder mixing, slow degradation
slowly degrading: slow degradation, requires a long retention time
seasonal: seasonal availability — requires storage
variable composition: high variability of composition between batches
dilutes the feed (low DM): low dry matter, dilutes the feed

Co-digestion — what to combine it with, what to watch out for

combines well
substrates: easily degradable — e.g. Maize silage (whole crop), Food waste, Sorghum, whole crop, Whey, Beet leaves and tops
In BMP studies, easily degradable substrates increased the yield of the mixture with slurry (synergy in some mixtures).^[1]

Dosing

No source limits on the dose for this substrate.

Sources of the process data

The co-digestion calculator will assess a specific mixture containing this substrate.

What it is and where it comes from

Loquat (Eriobotrya japonica), also known as the Japanese medlar, is a fruit tree grown in China, Japan and the Mediterranean region. The fruit is eaten raw or processed into jams and drinks. The waste consists of the thin peel and several large, hard seeds in each fruit. The dataset contains several records from a single study: peels and seeds. Because of the climate the plant is not grown commercially in Poland.

Properties relevant to digestion

The peel contains dietary fibre, polyphenols and pigments, and the seeds are rich in starch, but also contain bitter compounds and tannins as well as cyanogenic glycosides, characteristic of the seeds of many plants of the rose family. Under anaerobic conditions microorganisms usually cope with them at moderate doses, but it is sensible to introduce the material gradually. The tight structure of the seeds limits enzyme access, so comminution is very important.

How to read the spread of results

The records describe different fractions and come from a single study, so the difference is explained by composition, not uncertainty. The absence of data from other laboratories means that the result is only one reference point. The variety, ripeness, the share of flesh adhering to the seeds, the degree of comminution and the test parameters (inoculum, substrate-to-inoculum ratio, length) all have an effect. Comparison with other stone fruits is possible only with caution.

In biogas plant practice

Loquat is not available on a scale that allows deliveries to be planned. Individual quantities of waste may reach a biogas plant through deliveries from import processing plants or from collectors. In that case it is enough to treat it like other fruit wastes containing seeds: shred it, dose it gradually and monitor digestion. If the material is to be a regular component of the mix, a dedicated BMP test is necessary.

Methodology in brief

BMP is the amount of methane obtained from volatile solids (VS) in a batch test, given in m³ CH₄ per tonne of VS (numerically the same as NmL CH₄/g VS in the publications) and converted to normal conditions (0 °C, 101.325 kPa). The weighted mean gives each publication a total weight of 1, split equally between its results for the substrate — a paper testing twenty varieties does not outweigh a paper with a single sample. In inter-laboratory programmes the unit is the laboratory (total weight 1), and within it the weight of a test grows with the number of bottles (replicates). Results after pretreatment (e.g. thermal, chemical, enzymatic) are shown separately and are not included in the mean.

Solid lines are curves measured in the tests. Where a publication gives only the final result, we draw a first-order kinetic model, B(t) = B₀·(1 − e^−kt): only the end point comes from the publication, and the shape of the curve serves purely as visualisation — do not read the production on a particular day from it. For this substrate k = 0.245 d⁻¹ was assumed (median of rate constants k reported in the sources and/or fitted to the mean measured curves).

The statistics describe the spread of published results — a descriptive compilation, not a meta-analysis or a guarantee of plant yield.

Full methodology and correction policy

Bibliography

Zhao, C.; Yan, H.; Liu, Y.; Huang, Y.; Zhang, R.; Chen, C.; Liu, G. (2016). Bio-energy conversion performance, biodegradability, and kinetic analysis of different fruit residues during discontinuous anaerobic digestion. Waste Management 52, 295–301. DOI: 10.1016/j.wasman.2016.03.028 DOI

All sources of the site: bibliography.