Chemical preservatives in foodstuffs. III Hexamethylenetetramine as mold inhibitor and the antagonistic action of amino acids

Growth and respiration tests carried out on Aspergillus, Cladosporium and Penicillium molds have shown that certain amino acids such as 1-tryptophan and 1-cysteine and certain sulphydryl compounds such as glutathione and thioglycollic acid counteract the inhibitory action of hexamethylenetetramine. In the absence of hexamethylenetetramine, these compounds inhibit the growth of the molds. The dependence of the antagonistic action on the amino acid concentration differed for 1-cysteine and 1-tryptophan. The respiration of the mold was a maximum when equimolar concentrations of 1-cysteine and of the formaldehyde formed by the decomposition of hexamethylenetetramine were present in the culture media. The antagonistic effect of 1-tryptophan increased continuously with increasing concentration until the rate of oxygen consumption was the same as in the control test with no hexamethylenetetramine or antagonist present. The antagonistic effect of these four compounds on hexamethylenetetramine or on formaldehyde is evidently due to chemical interaction. The inhibitory effect of hexamethylenetetramine on the microbial cell may at least partly be due to its ability to inactivate enzymes such as the dehydrogenases

Effect of hot air and freeze drying on the volatile compounds of dill (Anethum graveolens L.) herb

Volatile compounds of fresh, hot air dried and freeze dried dill (Anethum graveolens L.) herb were studied by gas chromatography-mass spectrometry. Of the 25 volatile components identified, 16 the most abundant compounds were analysed quantitatively. The major primary aroma compounds were α-phellandrene, 3,6-dimethyl-2,3,3a,4,5,7a-hexahydrobenzofuran,β-phellandrene, limonene, α-pinene, p-cymene and myristicin. Severe loss of these components occured during the drying of dill. E.g. the retention of the benzofuranoid, the most important aroma component of the dill herb, was from trace to 1.3 % in hot air dried samples and 3.5—20 % in freeze dried samples. During the drying secondary aroma compounds are formed consisting over 50 % of the total volatiles. Among these phytadienes, especially neophytadiene, were the major components. The best result was obtained by freeze drying, but the product contained only one quarter of the total aroma compounds of the fresh dill herb

Composition of perch roe and keeping quality of roe products during cold- and frozen-storage

Proximate composition of whole roe bags and washed eggs of perch(Perca fluviatilis) was studied at different stages of maturity. Lipids and fatty acids of the roe were investigated in detail. Perch roe was processed using chemical preservatives, sugar, salt, and freezing and changes in the quality of the products were followed by chemical and sensory analyses during a one-year cold- and frozen-storage period. Mature roe as roe bags contained 13 % protein, 4 % fat and 1 % ash on wet weight basis. The amounts of protein and ash decreased somewhat when the roe was screened. The major lipids in perch roe were sterol and wax esters composing about 80 % of the total lipids. Polyenoic acids with dominant docosahexaenoic acid composed about half of the fatty acids in neutral lipids whereas saturated acids dominated in phospholipids. Frozen, washed roe was better in its quality during the one-year storage time as compared to heavy-salted, cold-stored roe containing preservatives which, in turn, was preferred to the light-salted, frozen roe or sugar-salted, cold-stored roe

Irradiation preservation of foods I. Prolongation of the keeping quality of fresh fish by radiation pasteurization

The prolonging of refrigeration shelf life (at 0° C) of pike and saithe was studied by radiation pasteurizing the fish with cobalt-60 gamma rays. The fish were packed whole in polyethylene bags. The radiation doses varied for pike between 150—1200 krad and for saithe between 150—250 krad. Organoleptic evaluations showed burnt off-flavour and off-odour in irradiated pike, which in fish that had been subject to small doses of 150 and 250 krad disappeared only after about one week of storing under refrigeration. For saithe no off-flavour was noticed when it was irradiated with a dose below 250 krad. After radiation at only 150 krad for saithe and 300 krad for pike the total bacterial counts in the muscle were reduced by nearly 100 per cent. With radiation doses of 150, 250 and 300 krad, the shelf life of pike under refrigeration increased 2.5, 3.5 and 5.2 times, respectively, compared with non-irradiated fish. The shelf-life times listed in the same order were 10, 14 and 21 days, but for non-irradiated fish only 4 days. For saithe the shelf life increased from 23 days (of non-irradiated fish) to 40 days when irradiated with a dose of only 150 krad. When whole fish were irradiated with large doses of 600 and 1200 krad, spoilage caused by bacteria was prevented for a long time while enzymatic spoilage caused by intestines was detected after 38 days as the contents of the intestines became decomposed and the flesh at the side of the abdominal cavity turned soft

Elintarvikkeiden säteilysäilöntä I. Tuoreen kalan säilyvyyden lisääminen säteilypastöroinnilla

The prolonging of refrigeration shelf life (at 0° C) of pike and saithe was studied by radiation pasteurizing the fish with cobalt-60 gamma rays. The fish were packed whole in polyethylene bags. The radiation doses varied for pike between 150—1200 krad and for saithe between 150—250 krad. Organoleptic evaluations showed burnt off-flavour and off-odour in irradiated pike, which in fish that had been subject to small doses of 150 and 250 krad disappeared only after about one week of storing under refrigeration. For saithe no off-flavour was noticed when it was irradiated with a dose below 250 krad. After radiation at only 150 krad for saithe and 300 krad for pike the total bacterial counts in the muscle were reduced by nearly 100 per cent. With radiation doses of 150, 250 and 300 krad, the shelf life of pike under refrigeration increased 2.5, 3.5 and 5.2 times, respectively, compared with non-irradiated fish. The shelf-life times listed in the same order were 10, 14 and 21 days, but for non-irradiated fish only 4 days. For saithe the shelf life increased from 23 days (of non-irradiated fish) to 40 days when irradiated with a dose of only 150 krad. When whole fish were irradiated with large doses of 600 and 1200 krad, spoilage caused by bacteria was prevented for a long time while enzymatic spoilage caused by intestines was detected after 38 days as the contents of the intestines became decomposed and the flesh at the side of the abdominal cavity turned soft.Tutkittiin hauen ja seitin kylmäsäilyvyyden lisäämistä (0° C:ssa) säteilypastöroimalla koboltti-60 gammasäteillä. Kokonaiset kalat pakattiin polyeteenipusseihin. Säteilyannoksien suuruudet vaihtelivat hauella 150—1200 krad ja seitillä 150—250 krad. Organoleptisissä analyyseissa havaittiin säiteilytetyissä hauissa palaneen sivumaku ja -haju, mikä pienillä säteilyannoksilla (150 ja 250 krad) käsitellyistä kaloista hävisi noin viikon kylmävarastoinnin jälkeen. Seitillä ei säteilyn aiheuttamaa sivumakua voitu todeta 150 krad:n annoksilla käsitellyissä kaloissa, mutta 250 krad:n annoksilla käsitellyissä kaloissa oli sivumaku selvä ja pysyvä. Säteilytettäessä haukea 300 krad:n annoksilla ja seitiä 150 krad:n annoksilla kokonaisbakteerien pitoisuudet pienenivät kalojen lihassa miltei 100 %:sesti. Hauen kylmäsäilyvyys lisääntyi 150, 250 ja 300 krad:n säteilyannoksilla samassa järjestyksessä lueteltuna 2.5, 3.5 ja 5.2 kertaisesti säteilyttämättömään kalaan verrattuna. Säilyvyysajat olivat niinikään samassa järjestyksessä lueteltuina 10, 14 ja 21 vrk, säteilyttämättömän kalan säilyvyysajan ollessa vain 4 vrk. Seitillä kylmäsäilyvyys lisääntyi 23 vrk:sta (säteilyttämätön kala) 40 vrk:een 150 krad:n annoksilla säteilytettäessä. Kokonaisia kaloja suurilla 600 ja 1200 krad:n annoksilla säteilytettäessä kalojen bakteriologinen pilaantuminen voitiin estää kokeen kestoaikana (38 vrk), mutta sitävastoin todettiin suoliston entsyymien aiheuttamaa pilaantumista suolensisällyksen liuetessa ja kalan lihan pehmetessä vatsaontelon puolelta

Kuumailma- ja pakkaskuivatuksen vaikutus tillin haihtuviin yhdisteisiin

Volatile compounds of fresh, hot air dried and freeze dried dill (Anethum graveolens L.) herb were studied by gas chromatography-mass spectrometry. Of the 25 volatile components identified, 16 the most abundant compounds were analysed quantitatively. The major primary aroma compounds were α-phellandrene, 3,6-dimethyl-2,3,3a,4,5,7a-hexahydrobenzofuran,β-phellandrene, limonene, α-pinene, p-cymene and myristicin. Severe loss of these components occured during the drying of dill. E.g. the retention of the benzofuranoid, the most important aroma component of the dill herb, was from trace to 1.3 % in hot air dried samples and 3.5—20 % in freeze dried samples. During the drying secondary aroma compounds are formed consisting over 50 % of the total volatiles. Among these phytadienes, especially neophytadiene, were the major components. The best result was obtained by freeze drying, but the product contained only one quarter of the total aroma compounds of the fresh dill herb.Työssä tutkittiin kuumailma- ja pakkaskuivatuksen vaikutusta lehtitillin (Anethum graveolens L.) haihtuviin yhdisteisiin. Tuoreesta ja kuivatuista tillinäytteistä tunnistettiin 25 yhdistettä kaasukromatografia-massaspektrometrian avulla, mutta kuivatusten vaikutusta seurattiin 16 pitoisuudeltaan suurimman yhdisteen osalta. Aromiaineiden pääkomponentit olivat α-fellandreeni, 3,6-dimetyyli-2,3,3a,4,5,7a-heksahydrobentsofuraani, β-fellandreeni, limoneeni, α-pineeni, p-symeeni ja myristisiini. Yhdisteiden pitoisuudet vähenivät huomattavasti kuivatuksen johdosta. Lehtitillin arominkannalta tärkeimmän yhdisteen, bentsofuraanijohdannaisen, määrästä oli kuumailmakuivatuissa tillinäytteissä jäljellä vain hivenmääristä 1 %:iin ja pakkaskuivatuissa näytteissä 3.5—20 %:a. Kuivatuksen aikana muodostui ns. sekundaarisia aromiaineita käsittäen yli 50 %:a haihtuvista yhdisteistä. Näistä fytadieenien, erityisesti neofytadieenin osuus oli suuri. Paras tulos, vain noin neljännes tuoreen tillin kokonaisaromimäärästä, saavutettiin pakkaskuivatuksella

Composition of perch roe and keeping quality of roe products during cold- and frozen-storage

vokKirjasto Aj-KAhvenen mädin koostumus ja mätivalmisteiden säilyvyys kylmä- ja pakkasvarastoinnin aikan