Lemon peel

Another group of natural flavoring ingredients comprises those obtained by extraction from certain plant products such as vanilla beans, Hcotice root, St. John s bread, orange and lemon peel, coffee, tea, kola nuts, catechu, cherry, elm bark, cocoa nibs, and gentian root. These products are used in the form of alcohohc infusions or tinctures, as concentrations in alcohol, or alcohol—water extractions termed fluid or soHd extracts. Official methods for their preparation and specifications for all products used in pharmaceuticals are described (54,55). There are many flavor extracts for food use for which no official standards exist the properties of these are solely based on suitabiUty for commercial appHcations (56). 

Aspinall, G.O., Craig, J.W.T., and Whyte, J.L. (1968) Lemon-peel pectin. Part I. Fractionation and partial hydrolysis of water-soluble pectin. CarbohydrJies. 1 442-452. 

Protoplast fusion induced by polyethyleneglycol and Ca was carried out between two auxotrophic mutants of Aspergillus sp. CH-Y-1043. The hybrids obtained showed significant differences in endopectinase activity and morphology compared to the prototrophic strain. Strains grown on lemon peel showed production improvement with respect to the parental strain. Since H15 hybrid showed up to 90% higher endopectinase production than the wild type CH-Y-1043, kinetics of enzyme production in Fernbach flasks and Fermentor (14L) by H15 were determined. 

Of the total, twenty six hybrids were assayed for endo-pectinase production on lemon peel, because we are interested in the enzyme production from this raw material. The relative activity of the hybrids with respect to Aspergillus sp. CH-Y-1043 is presented in Table 2. The highest increases (up to 46%) were observed in H5, H6, H15, Hll, H13, H14, HIO and H25 hybrids. In some hybrids, lower values of endopectinases production with respect to parental strain were obtained. 

Determinations were carried out in cell free filtrates obtained at 96 h of fermentation on 1% lemon peel. 

Four intraspecific hybrids were finally selected and they were grown to obtain the kinetics of endopectinases production and extracellular protein content. The course of endopectinase production by Aspergillus sp. CH-Y-1043 and hybrids during their growth on 1 % lemon peel is shown in Figure 1. 

Fig. 1 Comparison of endo-poctinase production between hybrids and parental strain grown on 1 % lemon peel.

Due to the potential for endo-pectinase production shown by the hybrid H15 on lemon peel, studies on fermentor using 3% lemon peel were performed. As shown in Figure 2A, maximum endopectinolytic activity was 80.0 U ml which is higher (60%) than the activity produced by hybrid H15 in 500 ml Erlenmeyer flasks we had previously observed in... 

Fig. 2 Endo-pectinase production by the hybrid H15 gro vn on 3% lemon peel in (A) 14 L fennentor and (B) Fembach flask (2L)...

Enzymatic treatment in the extraction of cold-pressed lemon peel oils... 

Table 1. Material balance in the non-recycling and recycling lemon peel oil recovery systems...

Both recycled and non-recycled essential oils met the standards for specific gravity, angular rotation and refractive index of the Food Chemicals Codex [22] and United States Pharmacopeia [23] for cold-pressed lemon peel oil. Results of gas chromatography analysis show the same compounds and levels in both systems, specially for the oxygenated compounds as citral (neral and geranial). Therefore, recycling the aqueous discharges to the extractor does not cause undesirable modifications. 

Measurements of pH were made with a glass electrode on 25 grams of lemon peel macerated in 100 ml. of distilled water in a Waring Blendor, and cleared by centrifugation. 

The two pinenes are obtained from Crude Sulfate Turpentine (CST), which is a side product of the sulfate cellulose process from pine trees. Limonene is present in orange and lemon peels [which provide different enantiomers/ )], and is a cheap by-product of the citrus industry. 

Miyake, Y. et al., Isolation of C-glucosylflavone from lemon peel and antioxidative activity of flavonoid compounds in lemon fruit, J. Agric. Food Ghem., 45, 4619, 1997. 

Baldi, A. et al., Identification of nonvolatile components in lemon peel by high-performance liquid chromatography with confirmation by mass spectrometry and diode-array detection, J. Chroma-togr. A, 718, 89, 1995. 

Lemon oil is obtained by pressing peel from the fruits of Citrus limon (L.) Burm. (Rutaceae). It is a pale yellow or pale greenish-yellow to dark green liquid with a characteristic lemon peel odor. 

Lemon peel oil is much more valuable than its juice therefore, extensive research efforts have been expended to determine its natural composition as a way to detect adulteration as well as to determine quality factors [6, 31, 32]. However, a few studies on lemon juice volatiles can be found [33-35]. Lemon oils are notable for possessing relatively low levels of limonene (more than 70%) and relatively high levels of a-pinene (1-2%), -pinene (6-13%), sabinene (1-2%) and y-terpinene (8-10%) [32]. The relatively high concentration of -pinene is thought to instil the green peely odour of lemon oil. The concentrations of aliphatic and monoterpenic aldehydes, (especially citral) as well as those of esters and alcohols are critical components in the perceived quality of the oil. As lemon oil is unstable, quality can deteriorate with improper storage, resulting in... 

Easter egg dyes are natural dyes that can be found around the home. They include blue from cabbage leaves or blueberries, orange from yellow onion skins, red from cranberries or raspberries, pale green from spinach leaves, and light yellow from orange or lemon peels. Dyes often have different colors in acidic and alkaline solutions. This enables them to be used as acid-base indicators. Many dyes are utilized as biological stains, see also Cosmetics Perkin, William Henry Pigments. 

Hie diagram show how limonene can be extracted from lemon peel by steam distillation. 

Aspinall, G. O., and Cottrell, I. W. (1970). Lemon-peel pectin. II. Isolation of homogeneous pectins and examination of some associated polysaccharides. Can. J. Chem. 48 1283-1289. 

Lemon Oil, Coldpressed, occurs as a pale to deep yellow or green-yellow liquid with the characteristic odor and taste of the outer part of fresh lemon peel. It is the volatile oil obtained by expression, without the aid of heat, from the fresh peel of the fruit of Citrus limon L. Burmann filius (Fam. Rutaceae) with or without the previous separation of the pulp and the peel. It is miscible with dehydrated alcohol and with glacial acetic acid. It may contain a suitable antioxidant. 

Introducing adsorbents into a supercritical fluid extraction system is an alternative attractive method to improve the selectivity for the citrus oil processing. Several applications using silica gel as adsorbent have been reported in the last decade [1-3]. Yamauchi and Saito [3] fractionated lemon peel oil into 3 fractions with gradual increase in pressure by supercritical fluid chromatography, where terpene rich fraction, ester rich, and alcohol and aldehyde rich fraction were obtained at 10 MPa, 20 MPa, and 20 MPa with ethanol as a cosolvent,... 

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