Efficacy of clove (Syzygium aromaticum (L.) Merr and Perry) powder as a protectant of groundnut kernels in storage

Abstract

Fungi and insects infestation of groundnut kernels in storage is a serious post-harvest problem. It leads to quality deterioration and loss of market value and kernels may become contaminated with aflatoxin (AF), which has many negative health implications when consumed. Currently, botanical pesticides are highly preferred to synthetic ones during storage. Effectiveness of preserving groundnut kernels against fungi and insect damage with Syzygium aromaticum cloves (fruits) powder were assessed in the laboratory. Another experiment was conducted under farmer’s storage conditions to evaluate potential of Syzygium powder to protect kernels against AF contamination. In the laboratory assessment, 3 kg kernel samples from sun-dried and undried pods were protected with 2 % (w/w) Syzygium powder. Kernels were kept under ambient conditions in sanitised and non-sanitised rooms for six months during the dry season. Unprotected kernels were kept as control and costs of applying the treatments were estimated. The experiment was repeated in the wet season. Under farmer’s storage, 50 kg kernel lots of 6 and 9 % initial storage moisture contents were protected with 2 % (w/w) Syzygium powder. Kernel lots stored without Syzygium powder served as control. These were packaged in interlaced polypropylene bags (IPPB) or polyethylene bags (PB) and stored in a farmer’s barn on farm. In dry and wet seasons, fungi colonised all kernels stored in laboratory from undried pods completely at three months. Pod drying costs GH¢ 8.99 (GH ¢0.82 = $ US1) and it was cost effective against fungi infection in dry season. Protecting kernels with Syzygium powder was estimated at GH¢ 17.87/100 kg lot and under the humid conditions in wet season, it proved cost effective against fungi infection. However, insect damage to the kernels was always higher after three months. Insects damage and fungi colonisation of kernels packaged in either PB or IPPB were reduced significantly (P < 0.05) at three months storage under farmer’s conditions, when they were protected with Syzygium powder. Aflatoxins do not use abbreviation at beginning of sentence were not detected in the kernels prior to storage. At three months, however, Syzygium-protected kernels had AF levels ranging between 0 and 29.30 µg/kg compared to 27.5-84.0 µg/kg associated with unprotected kernels. Syzygium powder applied at 2 % (w/w) was effective against fungi colonisation, insect infestation and subsequent AF contamination of kernels in storage. However, the kernels should be stored for three months.