The production of CN filtered cigarettes from Cannabis sativa L. are described as follows:
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1. Cannabis strains (Ghost train haze & Larry OG) of high THC (10–11% by weight) cannabis are organically grown without pesticides or added chemicals using nutrients/ingredients registered with OMRI (https://www.omri.org). OMRI offers independent review of brand name input products intended for organic farming and processing. OMRI's standards are based on the U.S. National Organic Program (NOP) and on the Canada Organic Regime (COR) standards. The plants are grown for ~120 days before hanging inverted under humidity and temperature controlled conditions (60% humidity, at 24°C for 11–13 days).
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2. After removing stems and seeds the plant buds, trichomes and small leaves (<3 cm) are chopped into small particles. Process chopping is accomplished using a rotating food processor blade for 5–7 minutes such that the final chopped material is between 0.04–10 mm in diameter before sifting with a 10 mm/10 mm opening/aperture stainless steel filter mesh screen.
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3. The plant material is homogenized in a batch cement-style mixer containing ~11.3 kg of material rotating ~20 turns/minute for 60 minutes.
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4. The plant material is humidified in a climate-controlled environment set at 60% humidity and 24°C under fan-mediated circulating air in 1 m × 0.6 m 0.6 m containers filled 75% full and rotated by inverting the storage container into an empty container every 12 hours for a period 2–3 days. The rotation is used to prevent the growth of fungi.
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5. The RYO cigarette rolling machine (RYO Machines LLC, Girard, OH) is prepared by lightly hand spraying cannabis contact points with food grade oil-based lubricant (e.g. vegetable, soy, canola, hemp, corn, etc) before loading the cigarette tube blanks. Unlike tobacco processing machines lubricant is required to prevent adherence of cannabis resin to the machine parts.
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6. To prevent plant material adhering to the pistons of the machine, the pistons that pack the plant material into the paper blanks are constructed of Teflon.
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7. The cigarette rolling machines are loaded with blank paper tubes (8 mm diameter, 70 mm length and a 12 mm filter) containing a ~1 cm cellulose acetate or cotton based filter. Filter tubes are loaded and the plant material is then filled into the tubes using a custom-made (Cranfords LLC) filling spout at a pressure of ~80 PSI designed to fill the tubes completely with processed plant material.
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8. The filling spouts are inserted into blank paper cigarette tubes to fill them with processed plant material.
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9. Filled cigarettes are collected in a tray approximately 0.3 m long × 0.1 m wide × 0.1 m deep and stored at ~30% humidity at 24°C for 12 hrs before packaging.
Particle measurement in CN was determined by digital caliper measurements of individual randomly sampled cigarettes. Individual cigarettes containing 700 mg of material were emptied into a conical tube and shaken vigorously to separate the dried plant matter. A subsample was then emptied to a plate and 50 particles/cigarette were randomly selected and measured from a cross-sectional area of 0.04 to 90 mm2.
Inverted passive smoldering was determined by hanging single CN, Camel Blue (CB) (RJR Winston-Salem, NC), or Newport (NP) (RJR Winston-Salem, NC) cigarettes (82 mm length × 8 mm diameter) by the filter region in an open Ball®16 oz canning jar immediately after igniting the cigarette for a period of 10–11 seconds. The smoldering coal for each cigarette was allowed to burn to a demarcated point where 5 cm of the cigarette was converted to ash with ambient temperature between 22–26°C and relative humidity of 20% and the smoldering rate was measured using a digital stopwatch.
Results & discussion
Cigarette smoke from tobacco or cannabis is formed by the condensation of chemicals formed by the combustion of dried plant material, pyrolysis and pyrosynthesis, and aerosolized particles in the cooler region immediately behind the burning coal (Browne, 1990). The tobacco coal temperature reaches between 800–900°C, and the temperature of the smoke during a puff drops rapidly as it passes through the cigarette rod (Touey & Mumpower, 1957). Burning finer-cut tobacco creates an aerosol with smaller particles, which are easier to inhale. So changing the filler cut particle size can influence the aerosol and chemistry (Centers for Disease Control and Prevention, 2010). In general, a courser cut width of shredded tobacco increases the number of puffs per cigarette compared to finer cut widths. This is due to the fact that cigarettes containing more coarsely cut tobacco burn less efficiently than those with finer cut shreds (Geiss & Kotzias, 2007). CN packing particle size distribution was determined by measuring a random sample of the length and width of the processed cannabis particles in CN cigarettes (n = 6) from different batches (n = 3, n = 2/batch). The sorted CN cigarette plant material filler particle area distribution for the 50 sampled particles/cigarette is shown in Figure 1. Using this analysis we determined that 50% of the CN cigarette filler particles had an area between 0.04 mm2 and 3 mm2 and 50% had an area between 3 mm2 and 90 mm2. Approximately 90% of the CN particles measured were between 0.5 mm2 and 25 mm2 in area. The normalized particle distribution represents visually selected samples of the particle size range for each cigarette and was not intended to represent the weighted size distribution of the particle areas within each cigarette. Randomized non biased imaging or sorting methods of cigarette particles to establish the relative weighted distribution of particle areas are planned for future experiments.