D-limonene concentration

D-Limonene Hard-Surface Cleaner D-Limonene Concentrate... 

A rapid loss of d-limonene, from 70 to 40 ppm for orange juice was observed in the 1 liter carton packs during the first days of ambient (25°C) storage (Fig. 4). Similar results were obtained by others (11,12) who claimed absorption by the film as the cause for this phenomenon. Again, the loss may vary between packages as shown in Fig. 5 The loss of d-limonene can be compensated for by increasing the initial d-limonene concentration. However, as d-limonene is a precursor to oxidative reactions of flavour compounds and since some flavour compounds are absorbed selectively at a higher rate, this is not desirable. 

Figure 4. d-limonene concentration in orange juice packed into glass jars and carton packs, stored at 25 C. 

Uses Used in preparing micro emulsion D -limonene concentrates Properties Amber cl. liq. sol. in chlorinated and terpene soivs. insol, or disp. in water, min. oil, aliphatic soivs., alcohols, and glycols sp.gr. 1.04 g/ml pH 6.0-8.0 (10% in DW) 75% cone. 

The following formulas are clear, microemulsions of d-Limonene and Aloe Vera. They represent the range of d-Limonene and Aloe Vera concentrations commonly used as degreasing solvent cleaners. These formulas are generally used by diluting in water (1->16 oz./gallon depending on the use requirements). The formulas are clear and exhibit a bloom effect upon dilution. 

Dilute concentrate 1 9 with water or charge "Vessel a with D-Limonene, Alcodet HSC-1000, and then Igepal CD-720. Mix until uniform. Charge a separate "Vessel B" with water, triethanolamine and Miranol FBS. Mix until uniform. Finally, add the contents of "Vessel A" to "Vessel B" and mix until uniform. 

Concentrated d-Limonene Biodegradable Deoreaser A Natural All-Purpose Micro-Emulsion Cleaner or Concentrate... 

TERPENELESS OIL. An essential oil from which the teqoene components have been removed by extraction and fractionation, either alone or in combination. The optical activity of the oil is thus reduced. The terpene-less grades are much more highly concentrated than the original oil (15—30 times). Removal of terpenes is necessary to inhibit spoilage, particularly of oils derived from citrus sources. O11 atmospheric oxidation the specific terpenes form compounds that impair the value of the oil for example, d-limonene oxidazes to carvone and y-terpinene to p-cymene. Terpeneless grades of citrus oils are commercially available. 

During the concentration of the press liquor to molasses, d-limonene is distilled and recovered. The recovery of c/-limonene is a function of evaporator capacity. Most citrus processors add the molasses back onto the wet peel. The difference between the press liquor and the molasses is the amount of distilled limonene. This is determined by Scott oil analysis. 

The term folded oils refers to concentrated oils. This typically involves a distillation process however, alcohol washing can also be used. Alcohol washing is based on the insolubility of d-limonene in 60% to 70% ethanol. These processes predominately remove terpene compounds, although aldehydes (octanal) are also reduced. Oils that are more than 20-fold concentrated are called terpeneless oils and are more stable. Distillation is predominately used by flavor houses. Flavor houses purchase cold-pressed oil, which is concentrated and fractionated. These fractionated portions are sold for flavorings or flavor precursors. 

Jia et al. (2005) undertook measurements in 30-50 homes in each of 3 cities in Michigan, USA using a tube type sampler that was thermally desorbed and an exposure period of 3-4 days. 49 compounds were identified indoors and indoor/ outdoor ratios ranged from 1 to 82. Significantly higher benzene, toluene and naphthalene concentrations occurred in homes with attached garages and D-limonene was higher in homes with smokers. Concentrations in air reported in one city are summarized in Table 3.2. 

Liquid Phase d-Limonene liquid phase concentration ppm (w/v) Kp/l Reference... 

D-Limonene may be inhaled when products such as citrus-scented air fresheners, perfumes and candles, cleaners and paints, are used indoors, especially without adequate ventilation. Terpenes are used in products for their solvent properties and, in some cases, for their odor. Limonene is a commonly identified indoor pollutant with time-averaged indoor concentrations in the range of 5-10 ppb, and much higher concentrations (>80ppb) can occur during the use of limonene-containing products. 

The peel sent to the feed mill contains the remainder of the oils that were not extracted in the cold-pressed oil recovery process. After liming and pressing, the press liquor is the source of the d-limonene recovered during molasses concentration... 

Stress-strain properties were determined as a function of absorbant concentration using a Universal Testing Instrument (Instron Corp., Canton, MA). The procedure used was adopted from ASTM Standards D882-83 (1984). Ten specimens were tested to obtain an average value. The amount of d-limonene absorbed was determined according to the Scott and Veldhuis (16) procedure. 

Figure 5- Concentration of d-limonene in orange juice stored at 25°C in various packaging materials. (BLANK = GLASS).

The release rate constants of AITC and D-limonene included in a-, P-, and y-CD can be estimated by means of Equation 1.2. Since the release rate of the flavor is very sensitive to the environmental humidity, it can be presumed that the included flavor was replaced by the water molecules. In Figure 1.25a and b, the release rate constant, k, is plotted against moisture concentration in humid air flowing through the sample bottle. The values are well correlated with the moisture concentration in the humid air, C. In both AITC and D-limonene cases,... 

FIGURE 1.25 Plot of release rate constant, k, against moisture concentration, C , in humid air flowing through the sample bottle for (a) AITC and (b) D-limonene. O a-CD, A (3-CD, y-CD. (From Shiga, H. et ah. Release characteristics of allyl isothiocyanate encapsulated in cyclodextrins, in Proceedings of the 10th International Cyclodextrin Symposium, Ann Arbor, MI, 2000, pp. 553-558.)... 

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