No abstract

The water contents of some dehydrated plant products have been determined in atmospheres of known humidity within the range 0% to Soy/, saturation, usually a t a temperature of 50' F. (roo c.) and also at 98.6" F. (37' c.), 140' F. (60' c.) and 176' F. (So0 c.) with dried potato and dried carrot.The non-diffusible colloids and soluble constituents each play a definite part in affecting the water content at any humidity ; the colloids have a relatively high water content a t low humidities and the soluble constituents have a low water content.The humidity/water relations of mechanical mixtures, such as soup powders, can he calculated from the proportions and properties of the constituents.

No abstract

No abstract

twice recrystnllised from hot ivntcr. Found C28.7, H 4.8, Zn 2G.8yo ; cnlculntnl for zinc lactate, C 29.6, I1 4.1, %II 26.9%.The iirJlitciice of pfZ ojt /c.r/itre.-Ati ncid, cheesy tnste nnd n clinrncteristit: testurc \vcrc noticen1)le in n scrnnible ~vlien tlie 1'11 of tlic s:irnplc ivns roughly i nntl Iicc:inic incrensingly nppnretit :it lower $1 viiliics. A norniiil tcsturc could lie obtnincd by iidjustitig the p I i of the reconstituted liquid to iibout 8.6 1)y t.lic ntltlition of caustic s o h Idore scrnnibling. Tliis treatnicnt iilso iinprovcd tlie flavour : for csnniple, tlic iliivour score4 of t h e ncitl snniples ivns incrciisctl froni 3 to 6. The iniprorcincnt wns, Iio\vever, liniitcd to the removal of the acid tiiste n i d the scr;uiililcs still lind nn unpliwritnt ofi-flnruur. Th:it tcstiire wis n function of pH wis confirnictl by niGling liyclrocliloiic iicid to a xiontin1 reconstituted snniplc until thc 1'11 wis 6 . 5 ; the scr;iuil)lc prcpnrel froni this niixtiirc hntl tlie siitiie chmncteristic tcst,urc :is tlic ncitl coniniercinj sniiiplcs. coitiiiiercid scfijiplcs nJ low $1 n d hi!gh F.F.d. coii/c)tt.-ii few coiiinicrciiil RIIIII~ICS of tlrictl egg of low pH were found to coiitnin lnrgc nnioiints nf F.F.:\., e.y., t,he ncitlity of tlic ctlicr cstrnct wns iis high ils 65 nil. .hilyscs of two sucli sninplcs :ire quoted below ; tlicse snniplcs had not I~ccit stored nt high tcnipcrntiircs. * dried otit o \ w pliosphorus pelitoxide a t 90' u., niid then cquilibruted to tlilTerent Iittiiosphcres in n series of stiigcs of incrensing huinitlities 1111 to n iitiisittiitni of 0.80 (SOYo scitnriitiotl) n 1~1 'tlum II scriw of llncc'Lliornu, i/id.. 135. llrccirril Scptembrr 17. 1013 1 lJnte.Sniitli, Ilruiilt~. iind lliiwtl~urni~, J.S.C.I., 11)1:1, 62, 1B7. 9 Cllelll. s: 1lll1.. LUW, (15% 3 .I. Hyyieiw. I!U!B, 39. 413. 4 annc, .I.S.C.I., 11M1, 80.44.

A knowledge of the density of air-free milk solids is required for calculation of the quantity of oxygen originally enclosed in sealed cans containing milk powder, and for conversion of percentages of oxygen obtained by analysis of the headspace gas to absolute units. Determination of this figure is a matter of some difficulty owing to the presence of entrapped ' air' in the spray-dried product. In the liquid displacement method there is also a danger of error due to incomplete ' wetting' of the particles, or to solution of one or other constituent of the powder, while in the gas-displacement method error may be introduced by solution or adsorption of the gas by the powder. Lea, Moran & Smith(l) obtained values of 1-29 by a pyknometer method with ethylene glycol, and 1-31-1-32 by a nitrogen displacement method for full-cream solids containing 27% of fat. Muers & Anderson (2), on the other hand, reported values of 1-26-1-28 by a liquid-displacement method using propyl alcohol. Further determinations have therefore been made by various modifications of all these methods. MATERIALRoller-dried powders were examined as manufactured and after drying in vacuo over P 2 O 5 at 37° C. or in the vacuum oven at 100° C. Spray-dried powders were reconstituted to 35 % solids in water at 40° C. to remove entrapped air and re-dried by freeze-drying to 3-5% moisture content, followed by vacuum drying at 37 or 100° C. as above. Freezedrying, after homogenization, might be expected to cause minimal damage to the constituents of the milk, though it will not reproduce the precise physical structure of the spray-dried particle. Drying on the steam bath caused obvious damage by caramelization, loss of solubility and aggregation of the fat globules. METHODSIn gas-displacement method A a weighed amount of powder was introduced into a glass bulb and the increase in pressure noted when a known volume of gas was added from a second bulb. In method B a bulb containing the powder was exhausted by means of a two-stage oil pump, and the amount of gas required to refill the bulb to atmospheric pressure and establish equilibrium read off on a gas burette. The apparatus in both cases was used in a constant-temperature room at 20° C.For the liquid-displacement method ethylene glycol and propyl alcohol were used, air being thoroughly exhausted from between the particles before finally filling up the density bottle. Neither liquid is ideal, since water is soluble in both, lactose is soluble in glycol, and fat is soluble in propyl alcohol. RESULTSThe results, which are summarized in Table 1, show that for anhydrous-separated milk solids both the gas-and liquid-displacement methods give the same result, but that the value obtained for anhydrous full-cream milk solids is considerably higher by the gasdisplacement method.

With One Text-figure) INTRODUCTION The loss of viability of seeds of Chewing's Fescue Grass has been a serious problem to both the producers in New Zealand and the trade in the United Kingdom. It has been shown by Foy (1934) that seeds with a high moisture content (20 %) held at 30° C. deteriorated rapidly after 10-14 days and even more quickly at 40° and 50° C. Seeds with a water content of 13 % deteriorated more slowly but it was not until the water content was reduced to and maintained at 5 % that seeds retained their viability at 30°, 40° or 50° C. for 42 days. Even at room temperature (16-20° C.) the loss of viability occurred after 4-5 months at 20 % water content and after 8-9 months at 13 % but at 5 % water content there was no loss. Foy discusses the effects of temperature and humidity that may occur during transport; Hyde (1935) has examined the effect of heating seeds to 50°, 60°, 70°, 80° and 90° C. with a view to working out the.conditions for artificial drying of the seeds before transport, and Lewis (1934) has found that, in some seasons, there was a marked loss of viability in storing these seeds in the United Kingdom.The experiments reported here were carried out in order to follow changes in viability of seeds held for long periods under conditions that might occur naturally or be provided in this country.The conditions chosen were: temperatures, 0°, 15° and 30° C; relative humidities of 45, 60, 70 and 80 %; and atmospheres of air, nitrogen, and nitrogen containing about 1 % of oxygen.The seeds, artificially dried in this country to a water content of about 10 %, were conditioned to the required relative humidity by exposing them in layers 2-3 mm. thick in desiccators with a sulphuric acid-water mixture giving the desired relative humidity.Seeds were stored in glass tubes (about 2 g. per tube) and sealed up after the required gas mixture had been introduced. The air-storage samples were held in desiccators above solutions of sulphuric acid and water to give the required humidities. The tubes were stored in constant temperature rooms until required for examination. As a check on the methods used, one tube from each set of humidities and gas mixtures was examined

SUMMARYMoisture content and temperature are of first importance in the storage of seeds. Seeds are usually stored in porous containers like sacks and paper bags, and their water content fluctuates with the humidity of the surrounding atmosphere. In sealed chambers, on the other hand, the humidity of the atmosphere will be determined by the water content of the seeds and, with different kinds of seeds in an enclosed space, an exchange of water will occur until equilibrium has been reached. This does not mean, however, that different kinds of seeds, or even different samples of the same kind will have exactly the same final water content, since the water content/humidity relations are affected by differences in structure, chemical composition and previous drying treatment; it is permissible, however, for practical purposes, to ignore the slight differences which occur between samples of the same kind of seed.