Title: Bromelain-mediated valorisation of shrimp moult shells using pineapple processing waste: hydrolysis optimisation and agronomic evaluation of the hydrolysate on Brassica juncea (L.) Czern.
Authors: Nguyen Thi Loan, Le Nguyet Hai Ninh, Le Thi Tam, Nguyen Thi Hoang Ngan
Volume: 10
Issue: 8
Pages: 75-83
Publication Date: 2026/08/28
Abstract:
Intensive whiteleg shrimp culture and pineapple processing generate two large, spatially co-located and poorly managed organic waste streams in northern Vietnam, yet neither is routinely converted into an agricultural input. Here, crude juice pressed from pineapple peel and core - an unpurified bromelain source requiring no commercial enzyme - was used to hydrolyse shrimp moult shells recovered from grow-out ponds in Ninh Binh, and the resulting liquid was evaluated as a fertiliser for mustard greens. Shell powder (30 g) was incubated with 100 mL of crude juice, and hydrolysis was tracked as total nitrogen (Kjeldahl), formol nitrogen (S?rensen) and their ratio (Nf/Ntot) across single-factor series of time (60-150 min), temperature (50-65 °C) and initial pH (5.0-6.5). Solubilisation rose steeply to 120 min and then plateaued; activity was highest between 55 and 60 °C and fell sharply at 65 °C; and pH 5.5 maximised Nf/Ntot at 46.0%. The optimised hydrolysate (55 °C, pH 5.5, 120 min) contained 0.876% total N and 0.403% formol N. In a randomised complete block field trial, the hydrolysate was applied at 0.1 L m?2 on days 7, 14 and 21 after transplanting. Relative to the water control it raised Brassica juncea plant height at 21 days by 30.3%, leaf number by 47.0%, fresh weight by 54.3% and marketable yield by 64.7%, and it matched mineral NPK to within 2.0-5.1% on every variable. Coupling the two waste streams therefore yields an on-farm fertiliser agronomically equivalent to mineral fertiliser without purchased enzyme, although the absence of replicate-level statistics and produce-safety data constrains these conclusions.