Olfactory and quantitative analysis of aroma compounds in elder flower (Sambucus nigra L.) drink processed from five cultivars

Fresh elder flowers (Sambucus nigra L.) were extracted with an aqueous solution containing sucrose, peeled lemon slices, tartaric acid, and sodium benzoate to make elder flower syrup. Aroma compounds emitted from the elder flower syrup were collected by the dynamic headspace technique and analyzed by GC-FID and GC-MS. A total of 59 compounds were identified, 18 of which have not previously been detected in elder flower products. The concentrations of the identified volatiles were measured in five elder cultivars, Allesoe, Donau, Sambu, Sampo, and Samyl, and significant differences were detected among cultivars in the concentration levels of 48 compounds. The odor of the volatiles was evaluated by the GC-sniffing technique. cis-Rose oxide, nerol oxide, hotrienol, and nonanal contributed to the characteristic elder flower odor, whereas linalool, alpha-terpineol, 4-methyl-3-penten-2-one, and (Z)-beta-ocimene contributed with floral notes. Fruity odors were associated with pentanal, heptanal, and beta-damascenone. Fresh and grassy odors were primarily correlated with hexanal, hexanol, and (Z)-3-hexenol.     

Microstructural and chemical investigation of subsurface hardened potatoes (Solanum tuberosum L.)

Summary Microstructural changes related to subsurface hardening of pre-peeled potatoes were investigated using cv. Sava potatoes peeled using an industrial peeler, a laboratory knife peeler or a hand knife peeler. The pre-peeled potatoes were packed in polymer bags and stored at 18°C for six days until cooking. Potato hardness and microstructure of the tissue was investigated. Cellulose and suberin in hard potato tissue increased linearly with increase in mechanical impact in a damage barrel. The area of cell walls and especially cell corners of mechanically damaged potatoes showed white autofluorescence in blue light. The number of layers of bricklike and autofluorescent parenchyma increased significantly with increasing hardness. Subsurface hardening was related to percentage cells with fluorescent gelatinised cell mass and curly cell walls in a depth of the potato tissue corresponding to the depth of maximum hardness.     

The influence of mechanical impact and storage conditions on subsurface hardening in pre-peeled potatoes (Solanum tuberosum L.)

Summary In investigating the effect of mechanical impact and storage conditions on subsurface hardening in boiled pre-peeled potatoes, potatoes (cv. Sava) were peeled using an industrial peeler, a laboratory knife peeler or a hand knife peeler, packed in polymer bags and stored at 4 to 18 °C for 6 days. Industrially peeled potatoes were significantly harder than potatoes peeled by hand or using a laboratory knife peeler. Potato hardening was not related to pectin methyl esterase activity (EC 3.1.1.11.). However, it was significantly correlated with mechanical impact from the peeler knives and by treatment in a damage barrel. Blunt knives resulted in harder potatoes than when sharp knives were used. An increase in storage temperature from 4 to 18 °C also increased subsurface hardening significantly. Maximum hardness was found below the wounded surface at a depth of 2–8 mm (average 4 mm).     

Effects Of Potassium,Phosphorus And Nitrogen Fertilization On Endogenous Ethylene And Quality Characteristics Of Apples (Malus Domestica L.)

Factor analysis of the data from experiment one with fertilization of ‘Spartan’ apples using various levels of nitrogen, phosphorus, and potassium and their interactions showed significances between ethylene and potassium, soluble solids and potassium, acidity and phosphorus, ethylene and phosphorus, and between ethylene and nitrogen. Factor analysis of data from experiment two with twenty apple cultivars showed that maturation time and ethylene were positively associated, whereas ethylene was inversely related to acidity that is reduced during the apple fruit maturation, and soluble solids are produced during apple fruit maturation. The effects of potassium on ethylene could be through promotion of enzyme activation, promotion of protein synthesis and increased solute transport in the xylem and phloem. Production of ethylene through soluble solids could be due to increased synthesis of the amino acid cysteine that is precursor of ethylene that may be extended to synthesis of other amino acids. The decreasing concentration of malic acid during fruit maturation may be due to increasing rates of several enzymes involved in the citric acid and glyoxylate cycles that are delivering precursors to synthesis of amino acids and porphyrins. The significant relationships between soluble solids and potassium and between acidity and phosphorus may increase the synthesis of nucleic acids and improve energy supply through adenosine phosphates. The significance between ethylene and nitrogen may also increase synthesis of amino acids, proteins and enzymes. On this basis it may be concluded that the three major minerals nitrogen, phosphorus and potassium are very important for apple fruit maturation because they may be involved in several biochemical processes.     

Influence of growth conditions on the value of crisphead lettuce

Crisphead lettuce was cultivated under different growth conditions. Sixteen batches differed in time of planting (early and late), total nitrogen supply (200 kg N/ha, 150 kg N/ha, 100 kg N/ha, 50 kg N/ha) and time of harvest (early and late). Based on chemical analysis and balance studies on rats the nutritive value of each 16 batches was determined. The protein content increased progressively from 16.00 to 19.88% with fertilization level. This increase in protein caused a significant drop in essential amino acids (g/16 g N) demonstrating a lower biological value of this protein. Early planting or early harvest resulted in a higher protein content than in lettuce of late planting or late harvest. Total dietary fibre content was approximately 25% of DM — and this value was not much influenced by the different growth conditions. Soluble dietary fibre was approximately 20–25% of total dietary fibre. Due to the high fibre content, energy digestibility was relatively low. The contents of Cd and Pb were below what is considered as ‘acceptable’ levels.     

Effect of fertilisation, development stage, mechanical impact and heating during processing on subsurface hardening in pre-peeled potatoes (Solarium tuberosum L.)

Summary Studies of the effect of fertilisation stress, harvest time, machine sorting, storage time, peeling and blanching of potatoes (Solarium tuberosum L.) were carried out. Mechanical impact by sorting before storage did not have a significant effect on hardness of pre-peeled potatoes. Potato hardness decreased significantly with the storage time for raw potatoes following an exponential function. Treatment of potatoes in a damage drum for 5 minutes (36 drops from 35 cm) increased the subsurface hardening, production of brick-like cells and deposition of suberin. Potato hardness throughout the whole potatoes increased with blanching time by blanching at 85 and 95 °C. It was concluded that development of potato hardiness occur because of two mechanisms. That is: 1) wound healing by periderm formation with deposition of suberin and: 2) activation of methyl esterase activity by blanching and subsequent crosslinking of demethoxylated pectin by calcium ions, respectively.     

Blanching of green bean (Phaseolus vulgaris)

Experiments with one and two steps blanching of green beans have been carried out. Inactivation of the peroxydase requires more heating than inactivation of the enzymes which gives rise to off flavour from aldehydes. When blanching for about one minute to inactivate lipoxygenase, aldehyde formation of flavour ceases. The content of vitamin C decreases during blanching according to a first order reaction. Since considerable loss of vitamin C occurs during blanching, the treatment time should be reduced to a minimum. During preblanching at 65–75 °C and final blanching, chlorophyll is degraded to pheophytin and the surface colour expressed by the Hunter-values (–a/b) increases with time which means that the colour of the beans changes from green to yellow. The firmness of beans, which was measured by use of a tenderometer, decreases during blanching according to a first order reaction with 40 kcal/mole activation energy. Preblanching at 65–75 °C increases the firmness of the beans linearly with treatment time. This increase in firmness is stable after final blanching at 95 °C and even after thawing of frozen beans.     

Changes in Quality Attributes during Growth of Leek (Allium porrum L.) for Industrial Processing

Abstract

A field experiment with leek was conducted in 1990 and 1991. Plant weight and the contents of nitrate and dry matter of the leek were measured on ten successive harvest dates each year. The yield of dry matter per square metre was calculated and related to harvest time. A maximum and virtually constant average plant weight was obtained from the beginning to the end of October (weeks 41–44). After this time the plant weight decreased. The yield of dry matter per square metre was virtually constant during the last two weeks of October and the first week of November.

The content of nitrate decreased steadily during the harvest period, while the content of dry matter was at a minimum in the middle of October (week 43).

The changes in nitrate and dry matter during growth could be explained by results from analyses of the different composition of the fractions of the leek. The content of nitrate and dry matter decreased from the outer to the inner part of the leek, in which the major part of the growth takes place during the weeks up to harvest.

A maximum yield of fresh weight and dry matter can be obtained after harvest in October or November (weeks 43–45) when the content of nitrate has decreased to a low and almost stable level.     

Interaction of vitamin C and flavonoids in elderberry (Sambucus nigra L.) during juice processing

A field experiment and two oxidation experiments in the laboratory were carried out. The content of the major anthocyanins, cyanidin-3-glucoside (Cy-3-G) and cyanidin-3-sambubioside (Cy-3-Sa), in the fresh fruits from the 13 cultivars were from 361 to 1266 and from 269 to 656 mg/100 g, respectively. The two minor anthocyanins, cyanidin-3-sambu-bioside-5-glucoside (Cy-3-Sa-5-G) and cyanidin-3,5-diglucoside (Cy-3.5-dG), occurred in concentrations between 5 and 47 mg/100 g. The content of ascorbic acid and quercetin in the fresh fruits of the cultivars varied from 6 to 25, and from 29 to 60 mg/100 g, respectively. Purging of the elderberry juice with N2 and/or addition of ascorbic acid reduced the oxidative degradation rate of the two major anthocyanins and quercetin. Ascorbic acid protected the anthocyanins, but not quercetin from oxidative degradation. Mixing of fruits with air during processing and even a low content of oxygen in the juice before tapping must be avoided by appropriate steps during processing. Improvement of the nutritional value of the elderberry juice and increased protection of anthocyanins against oxidative degradation may potentially be obtained by selection of cultivars with a high content of ascorbic acid.