A time-saving method for sealing Purdue Improved Crop Storage (PICS) bags

https://doi.org/10.1016/j.jspr.2018.04.002Get rights and content
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Highlights

  • Fold-tie method (FT) is an alternative method to the conventional twist-tie (TT) for sealing hermetic PICS bags.

  • FT reduces the bag sealing time by >34% over TT method.

  • FT can maintain the hermetic conditions of PICS bags similar to TT method.

  • FT can be used by farmers and food relief agencies storing large quantity of grain in PICS bags.

Abstract

Purdue Improved Crop Storage (PICS) bags were designed to reduce grain storage losses on smallholder farms. The bag consists of three layers: two high-density polyethylene liners fitted inside a woven polypropylene bag. Recently, farmer groups, development relief programs, and government food security agencies have shown interest in PICS bags for large-scale use. PICS bags are conventionally closed by a twist-tie (TT) method, which involves twisting, folding, and tying the lip of each layer individually with a cord. This is not only time and labor intensive, but also may affect the integrity of the liners. We evaluated three new bag closure methods: i) inner liner rolled onto itself and middle liner fold-tied (IR), ii) both liners folded together and tied (FT), and iii) both liners folded and tied separately (FS), along with the conventional twist tie (TT) method. The time to close partially or fully filled 50 kg-capacity PICS bags filled with maize grain was assessed. Results showed that FT was the most time-saving method, reducing bag sealing time by >34% versus the usual TT method. The average internal oxygen levels reached <2% within a week in bags containing grain highly infested with Sitophilus zeamais, while it remained >5% levels for less-infested bags. In both cases, insect population growth was suppressed. Oxygen depletion rates among tying methods remained the same regardless of the closure method used. When large numbers of bags need to be closed, the time-saving FT method is a good alternative PICS sealing method over the conventional twist-tie approach.

Keywords

PICS bags
Hermetic storage
Sitophilus zeamais
Maize storage
Bag sealing

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