Fruits water content

Ripening seeds, except where they are enclosed in fleshy fruit, lose water until their water content is in equilibrium with atmospheric humidity and at this stage they contain 5-20% water. The water contents of some seeds can be reduced still further with no adverse effects on viability, rather this can enhance their survival in the dried state (Roberts, 1973). The longevity of seeds in this anhydrobiotic state can be prodigious, lasting for several hundred years (Priestley Posthumus, 1982). 

To reduce the effort, another validation procedure is used for extension of the German multi-residue method to a new analyte. Actually, more than 200 pesticides can be analyzed officially with this method, which is the up-to-date version of the better known method DFG SI9. A typical validation is performed by at least three laboratories, which conduct fortification experiments at the same three levels with at least four representative matrices. These representative matrices are commodities with high water content (e.g., tomato), fruits with high acid content (e.g., lemon), dry crops (e.g., cereals) and commodities with high fat content (e.g., avocado). 

El Extraction and subsequent Uquid/liquid partition Plant material and foodstuffs with a water content exceeding 70g/100g and a fat content below 2.5 g/100 g Fruit, vegetables, juices... 

In countries where a strong environmental regulation for industrial wastewater exists, purification of waste streams from potato factories regarding both the fruit water and the pulp is required. Several attempts have been made to dehydrate the by-products and to utilize them for different purposes. Its high moisture content (80%) requires an expensive drying due to the problem of spoilage, if left untreated. The starch industry tries to sell as much pulp as possible as wet or partially dried cattle feed. However, the need for potato pulp by farmers is limited. Potato pulp is being used as cattle feed as well as a solid-state fermentation media for the production of different biomolecules. Conventional applications of potato pulp are listed in Table 16.2. 

Marked variations in the stability of 21 tinctures and 13 related singleentity plant compounds were noted (26). Bilia et al. (27) investigated the stability of 40% and 60% v/v tinctures of artichoke, SJW, calendula flower, milk thistle fruit, and passionflower. The investigation showed a very low thermal stability of the constituents from accelerated and long-term testing as determined by HPLC iode array detector and MS analyses. Stability was related both to the class of flavonoids and water content of the investigated tinctures. Shelf life at 25° C of the most stable tincture (passionflower 60% v/v) was about six months, whereas that of the milk thistle tinctures was only about three months. The stability of artichoke and... 

Since the moisture content of raw fruits varies widely, it is difficult to express typical values for water contents for various fruits. Amerine and Joslyn (2) stated that water in grapes ranges from 70 to 85%. The moisture content of several tree fruits grown in British Columbia was reported by Strachan et al. (4). The approximate moisture contents included apple, 85.1% pear, 83.9% peach, 86.9% and cherry, 78.4%. 

The water contents of several soft fruits such as strawberry, 90.2% raspberry, 85.0% and grape, 77.0%, were obtained by Zubeckis (5). These values are only general averages because the moisture contents are influenced by many known factors. 

For other plant food samples, appropriate sample sizes will depend on chlorophyll content and water content. Samples with low chlorophyll content may require 100 to 200 mg per replicate. For samples with low chlorophyll content and high water content (e.g., in florescences, fruit tissues, fruit juices), it is necessary to start with 2 to 3 g fresh weight sample and freeze dry it before extraction. Frozen food samples should also be freeze dried before extraction. 

The water content of fresh fruits and vegetables varies from approximately 80 to 95%, so radicals induced in the pulp by irradiation are not stable. However, the seeds, shells or skins can trap free radicals and so could be used to monitor radiation exposure. 

The visual appearance, clarity in particular, of packed products with high water content (vegetables, fruits, various cheeses, fresh meat) in packaging can be impaired by fogging caused by condensation of water as small droplets on the inside surface of the plastic film. In applications where perforated films with effective water vapor transmission are undesirable, antifogging agents with the properties of surface active substances, such as poly(oxyethylene) sorbitan monooleate are effectively used. 

Pectin is obtained from unripe apples or citrus fruit. In both cases the residues left after pressing to extract juice are used for pectin production. In the fruit, pectin is responsible for the firm structure. Apples, for example, have a firm texture despite a water content of more than 85%. Pectin is sold almost exclusively in powder form. 

Initial extraction of oil from oil fruit produces a cake of fruit skin, pulp, and kernel known as olive pomace or omjos. The value of this primary by-product of oil extraction depends on its oil and water contents, which are, in turn, determined by the method of oil extraction employed and the operating conditions. Pressure extraction yields a residue containing 4—5% oil, whereas classical presses leave 8-12% oil in the pomace (72). Pomace flours are used as animal feed due to their high content of protein, which is also of high quality. 

Fresh tomato fruit is about 96% water, and R. Willstatter and H. R. Escher isolated from this source 20 mg of lycopene per kg of fruit. They then found a more convenient source in commercicil tomato paste, from which seeds and skin have been eliminated and the water content reduced by evaporation in vacuum to a content of 26% solids, and isolated 150 mg of lycopene per kg of paste. The expected yield in the present experiment is 0.075 mg. 

Intermediate Moisture Foods (IMF s) are characterised by a moisture content of about 15 to 50% and by an aw between 0.60 and 0.85. Traditional IMF s, such as jams, fruit cakes and some ripened cheese are stable at ambient temperatures for various shelf periods (Table 3.59). Water content of IMF s may be lowered to a level which prevents microbial spoilage by the addition of humectants, pH adjustments and antimicrobial agents. Newer IMF s, such as designed for space rations, clinical nutrition and pet foods, can be prepared by adjusting the formulation of the product so that its aw is below 0.86 by use of the following techniques [11 ] ... 

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