Use of an oxygen absorber for disinfestation of consumer packages of dried vine fruit and its effect on fruit colour

The mortality of three life cycle stages of red flour beetle (Tribolium castaneum (Herbst)) was assessed in sealed 500 g packs of golden-coloured, sultana raisins, with or without the addition of a commercial O₂ absorber, Ageless^®. Assessments were undertaken at 30°C for 9 days, or 22.5°C for 20 days, or 15°C for 45 days. All fruit samples treated with O₂ absorbers produced 100% mortality, with no occurrence of a second-generation population, when incubated post-treatment at 27°C for 60 days. Fruit stored in an hermetically sealed bag produced 100% adult mortality at 22.5°C and 30°C but eggs and pupae survived; at 15°C mortality was not significantly different to the control culture. The effect of a low O₂ atmosphere generated by Ageless^® on fruit colour was assessed using the same temperature regimes over a 28, or 56, or 84-day storage period. Fruit colour changes were measured using the CIE tristimulus L^*, a^*, b^* measuring system. Low storage temperature (15°C) and low O₂ atmosphere both maintained fruit colour during the experimental storage regimes. There were significant negative effects on fruit colour at the higher temperature (30°C) and longer storage period without a modified atmosphere.