# Chemical and Sensory Evaluation of Silicone and
###### Abstract  
Alkylmethoxypyrazines (MPs) are a class of compounds that can elicit undesirable aroma and flavor characteristics in wine, and resist remediation using traditional wine making approaches. MPs are grape-derived constituents as well as contaminants from _Coccinellidae_ beetles present during wine processing; the latter eliciting an off-flavor referred to as 'ladybug taint'. In this study we investigated the capacity of two plastic polymers--one silicone-based, the other polylactic acid-based--applied with varying surface areas to reduce concentrations of isopropylmethoxyprazine (IPMP), _sec_-butylmethoxyprazine (SBMP) and isobutylmethoxyprazine (IBMP) in a Merlot wine using multi-dimensional gas chromatography coupled with mass spectrometry and headspace solid phase microextraction (SPME-MDGCMS). The impact of treatments on the sensory characteristics of the wine (descriptive analysis) and volatile aroma compounds (VOCs) (SPME-MDGCMS) was also investigated. Results showed substantial reductions for all of the target odorants: up to 38%, 44% and 39% for IPMP, SBMP and IBMP, respectively, for the silicone polymer, and up to 75%, 78% and 77% for IPMP, SBMP and IBMP, respectively, for the polylactic acid polymer. These polymers had no or minimal effect on VOCs at applications of 200 cm\({}^{2}\)/L for silicone or for all polylactic acid treatments. Sensory impacts were less clear, but generally showed minimal effect from the treatments. Taken overall, the data confirm the utility of both polylactic acid and silicone polymers in reducing elevated levels of grape-derived MPs, as well as potentially improving wine contaminated by ladybug taint. methoxyprazines; ladybug taint; silicone; polylactic acid Article Chemical and Sensory Evaluation of Silicone and  
Polylactic Acid-Based Remedial Treatments for  
Elevated Methoxyprazine Levels in Wine  
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from members of the _Coccinellidae_ species, particularly _Harmonia axyridis_ and _Coccinella septempunctata_ during grape harvest and processing [3; 4; 5]. Extraction of MPs from these beetles during winemaking procedures can lead to off-flavors known collectively as ladybug taint [3]. The taint in juice and wine is characterized by detrimental aromas and flavors that include \"peanuts\", \"asparagus\", \"green bell pepper\", and \"canned green beans\" [3]. MPs are very potent, with olfactory perception thresholds ranging between 0.3-16 ng/L, and concentration ranges of 0-60 ng/L reported in commercial wines. Four MPs have been identified as naturally occurring in wines: _iso_-propyl-methoxypyrazine (IPMP), _sec_-butylmethoxyprazine (SBMP) _iso_-butylmethoxyprazine (IBMP) and dimethylmethoxyprazine (DMMP) [2]. IPMP, SBMP and IBMP have all been linked to ladybug taint, with IPMP being the main contributor [4; 5; 6]. _Harmonia axyridis_ populations in Canada, USA and Europe have increased during the last decade, a phenomenon partly attributed to climate change, whereby warmer winters are allowing populations to survive in larger numbers. This has translated into higher numbers of beetle infestation events during harvest in many vineyards in these regions [7]. Additionally, cooler, wetter autumns and years with extreme temperature variations may also be contributing to increased MP levels in grapes and their subsequent wine [8; 9]. MPs are relatively stable during alcoholic fermentation and wine ageing, necessitating remediation in cases of high MP must or wine. Several remedial options have been examined in the literature, with varying degrees of success reported. Juice clarification can reduce MP loads by up to 50% [10; 11; 12; 13]. Similarly, thermo-vinification and juice heating can be moderately successful (up to 50% MP reduction) [14], but may lead to undesirable sensorial changes in wines [15]. Selective yeast usage was shown to be ineffective or even detrimental, with one commercial yeast strain increasing MP concentrations [16].