Andhra Pradesh has five operational sugar mills. The other 24 have closed because of insufficient cane supply and financial problems. The mills that remain are drawing cane from scattered sources, which means longer delays between cutting and crushing. And that delay is where the dextran problem starts. Bacterial load in harvested cane doubles within 30 to 40 minutes if left unchecked. A biocide programme set for a short supply radius will under-treat when the cane is coming from 50 kilometres away.
Innovacorp India supplies sanitation biocides for Andhra Pradesh's operational mills working with this scattered cane supply. This page is about biocide timing, the difference between oxidizing and non-oxidizing grades, and how to adjust the dose when the delay is not constant.
The Lok Sabha reply from April 2025 gives the number: of 29 sugar mills in Andhra Pradesh, 5 were operational in the 2024-25 season. The remaining 24 could not take up crushing due to "non-availability of sufficient sugarcane, other financial problems." Andhra Sugars closed its Tanuku plant from 1 April 2025 and suspended crushing at Bhimadole for 2025-26, citing "non-availability of viable quantities of sugar cane for past few seasons."
The district-level area data shows how scattered the remaining cane supply is. Visakhapatnam district had 23.64 thousand hectares under cane in 2020-21; by 2024-25 the estimate was 2.1. West Godavari fell from 3.11 to 0.7. East Godavari from 1.72 to 0.3. In Vizianagaram, two mills closed and farmers now transport cane to Srikakulam district for processing. In Chittoor and Tirupati, cultivation fell by over 96%, and SNJ Sugars in Nelavoy is the only operational plant in that region.
For the five mills still running, the cane comes from a wider catchment area than before. Longer transport distances mean longer delays between cutting and crushing. That is the condition the biocide programme has to handle.
Leuconostoc mesenteroides is the primary bacterium responsible for dextran formation in sugarcane juice. It converts sucrose into dextran, a gummy polysaccharide that increases juice viscosity, reduces clarification efficiency, and lowers sugar recovery. The bacteria are soil-borne and enter the cane through cut ends and damaged tissue.
Freshly harvested cane begins deteriorating almost immediately. Within 30 to 40 minutes, bacterial load doubles if left unchecked. Every 1000 ppm of dextran can cause a 3-4 kg sugar loss per ton of cane. The loss is not linear with time, because the bacterial population grows exponentially once it is established. A mill that crushes cane 4 hours after cutting has a very different microbial load from one that crushes at 12 hours.
The practical implication is that biocide timing should match the actual harvest-to-crush interval, not a fixed schedule. In Andhra Pradesh's current supply pattern, that interval is not constant. A biocide programme that works on Monday may underperform on Wednesday if the cane source changes.
Oxidizing biocides, such as silver hydrogen peroxide, act fast and break down without residue. They are suitable for shock dosing or when immediate microbial reduction is needed. The hydrogen peroxide attacks cell membranes through oxidation, and the silver ions provide a secondary antimicrobial effect. The advantage is speed; the limitation is that the oxidizing capacity is consumed by organic matter in the juice, so the persistence is limited.
Non-oxidizing biocides, such as THPS and carbamates, persist longer in the system. They are better for maintaining sterile conditions through the milling tandem when the cane delay is extended. The mechanism is different from oxidizing biocides; they disrupt specific metabolic pathways rather than oxidizing cellular components. The persistence means a single dose can protect the juice for a longer period, which matters when the cane supply is irregular.
For a mill with variable cane delay, a combination may be appropriate: an oxidizing biocide for immediate reduction at the mill entry, followed by a non-oxidizing biocide to maintain control through the tandem. The specific combination depends on the mill's configuration and the delay pattern.
The dose should not be fixed through the season. When the cane delay increases, the microbial load at the mill entry is higher, and the biocide demand is higher. The dose should be adjusted upward, or a more persistent grade should be used, or both.
The starting point is to measure. Dextran can be measured in the juice using the lead acetate and lead nitrate method, or a rapid dextran test. The bacterial load can be estimated by standard plate count. A mill that measures its dextran and bacterial load at the mill entry and after the tandem can see whether the biocide programme is controlling the problem or just treating the symptom.
The specific dose depends on the biocide chemistry and the juice characteristics. The TDS for each grade gives the recommended range. The jar test or a plant trial confirms the actual dose. A generic recommendation is not reliable when the cane supply is as variable as it is in Andhra Pradesh's current situation.
| Parameter | Typical Value / Range |
|---|---|
| Biocide type | Oxidizing (silver hydrogen peroxide) or non-oxidizing (THPS, carbamate), grade dependent |
| Appearance | Clear liquid, grade dependent |
| Dosing point | Mill entry, juice screen, or mixed juice, depending on the mill configuration |
| Dosing range | TDS on request, adjusted to cane delay and microbial load |
| Dextran loss reference | 3-4 kg sugar loss per ton cane per 1000 ppm dextran |
| Shelf life (unopened) | TDS on request |
Specification values vary by product grade. Confirm final spec after plant trial against your cane supply pattern and juice analysis.
Supplied in standard industrial packing. Pack sizes on request. Store in sealed containers away from direct sunlight and incompatible materials. Follow the safety data sheet for handling and personal protective equipment. Oxidizing and non-oxidizing biocides should not be mixed before dosing unless the TDS confirms compatibility.
Q: How should biocide dose be adjusted when cane delay exceeds 12 hours in Andhra Pradesh mills?
A: Bacterial load in harvested cane doubles within 30-40 minutes if left unchecked, and the dextran formation continues as long as Leuconostoc has sucrose available. When cane delay exceeds 12 hours, the biocide programme should shift toward a higher dose of a persistent non-oxidizing grade or a combination of oxidizing and non-oxidizing products. A fixed dose set for 4-6 hour delay will under-treat at 12+ hours. The specific adjustment should be confirmed by measuring dextran or bacterial load in the juice at the mill.
Q: When should oxidizing versus non-oxidizing biocide be used?
A: Oxidizing biocides like silver hydrogen peroxide act fast and break down without residue, making them suitable for shock dosing or when immediate microbial reduction is needed. Non-oxidizing biocides like THPS and carbamates persist longer in the system and are better for maintaining sterile conditions through the milling tandem when cane delay is extended. The choice depends on the delay pattern and the specific contamination point.
Q: How much sugar loss does 1000 ppm dextran cause?
A: Every 1000 ppm of dextran can cause a 3-4 kg sugar loss per ton of cane. Dextran also increases juice viscosity, reduces clarification efficiency, and affects crystallization. In mills with delayed crushing, the dextran level can rise quickly, which is why biocide timing matters. The dextran level should be monitored, not assumed.
Q: What biocide programme suits Andhra Pradesh's 5 operational mills?
A: Andhra Pradesh has 5 operational mills in 2024-25, down from 29. These mills draw cane from scattered sources with variable delay. The programme should be built around the actual harvest-to-crush interval, not a fixed dose. A mill receiving cane from long distances needs a more persistent biocide or a higher dose than one with a short supply radius. The specific grade and dose should be confirmed against the mill's cane supply pattern and juice analysis.
Call: +91-9312871070 — to discuss biocide selection for your mill's cane supply conditions.
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