Titratable Acidity Ratio Research Articles

Determining the harvest time of camu-camu [Myrciaria dubia (H.B.K.) McVaugh] using measured pre-harvest attributes

The characterization of the physical, chemical, and physiological parameters of camu-camu fruit at various stages of development may help to determine the optimal harvest time of this fruit. Camu-camu fruits from a rural property in the municipality of Cantá/RR were marked and harvested at 53, 60, 67, 74, 81, 88, 95, and 102 days after anthesis (DAA) during six seasons (years) of study. The following attributes were measured: fresh weight, diameter, total soluble solids (TSS), starch, titratable acidity (TA), the TSS/TA ratio, total and reducing sugars, total and soluble pectins, pectic enzymes, vitamin C content, and the production of CO2 and ethylene. The combination of the absence of a climacteric peak in the respiratory pattern and the low and invariable production of ethylene during development indicates that camu-camu fruit is non-climacteric. The best harvest time for this fruit occurred between 88 and 95 days. During this period, measured parameters such as coloration (85% and 100% red, respectively), high TSS:TA ratio, reduced TA, and high TSS, reducing sugar, soluble pectin, and vitamin C concentrations achieved their optimal.

Aplicação de recobrimento prolonga a qualidade pós-colheita de laranja 'Valência Delta' durante armazenamento ambiente

The objective of this study was to evaluate the effect of the application of carnauba-based wax on the quality and conservation of the Orange cv. Valencia Delta produced in an area of semi-arid climate, during ambient storage (24 ± 2 oC and 40% ± 5 RH). The influence of the use of the coating on the physical properties (weight loss, peel moisture and flavedo colouration) and the physicochemical properties (soluble solids, titratable acidity, pH, soluble solids / titratable acidity ratio, ascorbic acid, yellow flavonoids and total polyphenols) was evaluated every four days for a period of 28 days. An increasing weight loss was seen during storage, the coated fruits however, lost weight at far lower rates than the control fruits. Accordingly, peel moisture decreased during storage, being more pronounced in the control fruits. The levels of soluble solids, titratable acidity, ascorbic acid, yellow flavonoids and total polyphenols increased, while the ratio of soluble solids to titratable acidity and the pH decreased during storage. The application of a carnauba-based coating prolonged the postharvest life of the 'Valencia Delta' orange grown in the state of Ceara, through a significant reduction in weight loss, enhancement in the brightness of the flavedo and maintenance of the physical and physicochemical properties during ambient storage.

Prediction of the sensory acceptance of fruits by physical and physical–chemical parameters using multivariate models

Data about overall liking and physical and physical–chemical analysis for oranges, pineapples, and grapes were analyzed by Principal Component Analysis (PCA). Results showed that solid soluble variables, soluble solids content/total titratable acidity ratio, and pH contributed positively and titratable acidity contributed negatively to the overall liking grade, indicating preference for sweeter and less acidic fruit samples. Consumer acceptances were calibrated against physical and physical–chemical measurements of those fruits using Multiple Linear Regression. The models obtained were then validated and tested using the widely used methods of y-randomization and external validation. In all cases, multivariate models presented R2 values >0.7, which were higher than for the univariate models. Therefore, the models built and validated for oranges, pineapples, and grapes can be used to predict the consumer acceptance by easy and quick physical and physical–chemical measurements, ensuring that fruit commercialization takes sensory acceptance into consideration.

Avaliação da qualidade de frutos de quatro genótipos de abacaxi para consumo in natura

A abacaxicultura brasileira sofre prejuízos pela presença da fusariose, devido à suscetibilidade das principais cultivares plantadas no País. Programas de melhoramento genético vêm buscando novas alternativas para os produtores de abacaxi com o desenvolvimento de novas cultivares resistentes à fusariose. O objetivo deste trabalho foi comparar atributos qualitativos de duas cultivares resistentes à fusariose com duas cultivares tradicionais no mercado de abacaxi in natura. Foram utilizados frutos de dois genótipos resistentes à fusariose (cv. Vitória e híbrido EC-93) e duas cultivares suscetíveis comerciais (Pérola e Gold), sendo avaliadas as características de qualidade do fruto como: massas do fruto, da coroa, da polpa e do cilindro central; diâmetros do fruto e do cilindro central; comprimento do fruto; firmeza; pH; acidez titulável; teor de sólidos solúveis (SS); ratio (SS/AT); teor de vitamina C, e parâmetros de cor L, a, b, e ângulo hue (ºh) da polpa. Os resultados mostraram que a cv. Vitória, de polpa branca, apresentou frutos com características físicas similares à da cv. Pérola; no entanto, apresentou menor cilindro central, maior teor de sólidos solúveis e acidez mais elevada, resultando em relação SS/AT inferior. A casca dos frutos da cv. Vitória apresentou resistência mecânica superior à do fruto da cv. Pérola. O híbrido EC-93 apresentou índices de qualidade de fruto inferiores aos observados para as cvs. Gold, Vitória e Pérola. A cv. Gold apresentou a maior massa do fruto (1,30 kg), não diferindo da cv. Vitória (1,14 kg).

Acidity dynamics of hydrolyzed sweet condensed milk in the storage process

There is almost no market for low-lactose products in Ukraine, except infant formulas, that is why, about 10 % of the population are limited to the consumption of dairy products. Recently, there are attempts in creating dairy products wherein the lactose is partially hydrolyzed by the β- galactosidase preparations. Creating low-lactose dairy products is of great social importance, the regulation of sugar profile of dairy products by the lactose fermentation is relevant. Herewith, lactose is split into monosaccharides glucose and galactose, the chemical composition of milk is changed, which enables saving sucrose when manufacturing sweet condensed milk, in the finished product organoleptic indicators are improved, excluded the possibility of lactose crystallization in sweet condensed milk during storage, the new products are designed for people intolerant to lactose and a wide range of people. The studies of determining the quality of new products are given in the paper, the organoleptic and physico-chemical characteristics of hydrolyzed sweet condensed milk were defined for the first time: water activity, osmotic pressure, weight ratio of dry solids, titratable and active acidity in fresh products and during storage.

Qualidade de fruto e produtividade de pessegueiros submetidos a diferentes épocas de poda

Com o presente trabalho objetivou-se avaliar as características produtivas de diferentes genótipos de pessegueiro (Prunus persica (L.) Batsch.), submetidos a podas em épocas distintas na região de Pelotas-RS. O experimento foi conduzido em uma área experimental pertencente à Embrapa Clima Temperado (CPACT), durante os anos de 2009 e 2010. Os tratamentos foram compostos de combinações de três épocas de poda [poda de inverno (PI), poda de inverno mais poda de verão (PIV) e poda de verão (PV)] e três genótipos [Cascata 805, Cascata 834 (BRS Kampai) e Cascata 952 (BRS Rubimel)], resultando em nove tratamentos distintos. Para as variáveis firmeza de frutos, pH, sólidos solúveis (SS), acidez titulável (AT), relação SS/AT e cor, não foi verificada interação entre os fatores estudados. Os frutos de BRS Kampai apresentaram maior firmeza, assim como a poda apenas no período de verão. O genótipo BRS Kampai apresentou frutos com maior SS e AT dentre os estudados e as plantas de BRS Kampai e BRS Rubimel apresentaram frutos com coloração vermelha mais intensa de epiderme, independentemente da época de poda. Verificou-se que a poda apenas no período de verão induziu à produção de frutos menores. Os genótipos BRS Kampai e BRS Rubimel apresentaram produtividades semelhantes, independente do sistema de poda aplicado. Em geral, as características físico-químicas dos frutos não são alteradas com as variações de época de poda estudadas. No entanto, as variáveis de qualidade física e as relacionadas com a produção sofrem influência direta da época de poda.

Effect of accessions on the chemical quality of fresh pumpkin

Twenty (20) fresh pumpkin fruits were assessed for dry matter, total soluble solid, total sugar, reducing sugar, titratable acidity, pH, ascorbic acid and sugar-to-acid ratio. Statistically significant (P < 0.01) differences were found for dry matter, total soluble solid, total sugar, reducing sugar, titratable acidity, ascorbic acid, pH and sugar to acid ratio for the 20 fresh pumpkin fruit accessions. Accession 8007 had the highest dry matter, total titratable acidity, total soluble solid and total sugar content. Accession 8007 was also found to have high concentration of ascorbic acid although pumpkin fruit accession 8807 had the highest ascorbic acid. Pumpkin accession 4707 had the highest amount of reducing sugar and titratable acidity while accession 7707 had the highest pH and total soluble solid/ total titratable acid (TSS/TA) ratio. Pumpkin accession 8007 was found to be superior variety with the highest nutritional value while accession 1307 and 3907 were found to be inferior to the accessions evaluated in this study. Key words : Pumpkin, accession, Ethiopia, nutritional value.

Inter- and intra-tree variability in quality of figs. Influence of altitude, leaf area and fruit position in the canopy

Shading effect on quality of fig (Ficus carica L.) is noteworthy within the tree. Leaf area and canopy density enhanced shade conditions and altered microclimate inside ‘Bouhouli’ fig tree. With leaf area index (LAI) of about 3.3 there was a tendency to have smaller, firmer and lighter skin coloured fruit inside the canopy. Altitude level had a little influence on quality of ‘Bouhouli’ figs. Though, fruits from mountainous zone of ‘Djebba’ ripened earlier and were heavier and less acid than fruits from nearby plain of ‘Thibar’. Position of the fruit in the canopy significantly affected fruit firmness, titratable acidity (TA) and TSS:TA ratio (p<0.01). There were greater fruit loads with soften receptacle and lower acidity in the outside canopy positions than in the inside positions. No differences exist in dry matter (18.7%) and soluble solids content (18.3%) between light exposed and shaded fruits. Yet, TSS:TA ratio was higher in figs harvested from the periphery. Sugar and organic acid concentrations were little influenced by fruit position in altitude or in the tree. Glucose, fructose and sucrose showed the same proportions 0.47, 0.38 and 0.15, respectively, inside and outside the canopy. Citric acid, the predominant organic acid in figs, had comparable concentrations in fruit from inner and outer part of the tree. Citric acid levels were though different (p<0.05) between fruits from the two locations (1.95mequiv./100g FW in the plain versus 2.80mequiv./100g FW in the mountain). Temperature was positively correlated with fresh weight (r=0.74*) but negatively correlated with firmness and titratable acidity (r=−0.91**). High temperature degrees during maturity enhance fruit enlargement and softening and reduce acidity of fig juice. Growing figs in mountainous and uneven zones with high altitude remains profitable to farmers living these areas. To improve light penetration into the foliage, summer pruning, leaf removal and shoot vigour control, little practiced in fig species, are recommended close to maturity and lead to homogeneous quality of fig crops.

Evaluation of Fourier transform-NIR spectroscopy for integrated external and internal quality assessment of Valencia oranges

Diffuse reflectance near infrared (NIR) spectroscopy was explored as a non-destructive method to detect external and internal quality of Valencia oranges. The study compared three different Fourier transform NIR acquisition methods, namely, a fibre-optic probe for solid samples (SP), an integrating sphere (IS) and an emission head (EH). Fruit quality attributes measured included mass, colour index, total soluble solids (TSS), titratable acidity (TA), maturity index expressed as TSS:TA ratio and vitamin C. Partial least squares regression was applied to spectral data to develop prediction models for each quality attribute and by randomly dividing the data into calibration and independent validation sets. To test robustness, a set of fruit harvested from another location was used for external validation. Fruit mass, colour index, TSS and vitamin C were predicted with significant accuracy showing RPD-values of 3.53, 1.99, 1.87 and 1.33, respectively. The spectral acquisition method had a significant influence on the calibration regression statistics and accuracy of prediction. The models developed using the EH gave the best prediction statistics for mass (R=0.96, RMSEP=10.45g), colour index (R=0.83, RMSEP=0.82) and vitamin C (R=0.66, 8.01mg/100mL), while the IS gave the best prediction for TSS (R=0.83, RMSEP=0.58). The model parameters remained fairly constant when the models were validated using fruit from another location, indicating high level of model robustness. Good prediction statistics observed when using EH demonstrated the potential of this spectrometer as a non-destructive tool to holistically evaluate external and internal quality parameters.

Effect of hyperbaric pressure and temperature on respiration rates and quality attributes of tomato

Previous work with hyperbaric treatment of tomato focused on application at lower temperature (13°C). In this work, hyperbaric treatment at varying pressure levels (i.e., 0.1, 0.3, 0.5, 0.7 and 0.9MPa) at ambient temperature (20°C) was tested as a potential alternative to conventional refrigerated storage (0.1MPa at 13°C) to preserve tomato quality. The experiments were divided into 3 phases: (1) 4 day of hyperbaric treatment, (2) 5 day of post-treatment ripening, and (3) 10 day of post-treatment ripening. Respiration rate (RR) of the tomatoes was continuously monitored during the course of the hyperbaric treatments. Quality attributes were assessed immediately after removal from the hyperbaric treatments and after 5 and 10 day ripening at 20°C after removal from the treatments. Hyperbaric treatments at ≥0.3MPa resulted in RR equal or higher than the RR in control fruit (0.1MPa at 20°C). The lowest RR was obtained from tomato stored at 0.1MPa at 13°C. Hyperbaric treatment at 0.5, 0.7 and 0.9MPa significantly reduced weight loss, retained color, firmness, total soluble solid (TSS), titratable acidity (TA) and TSS:TA ratio at similar levels as the tomato treated at 13°C and 0.1MPa. Firmness after treatment was highest for fruit from 0.1MPa at 13°C and from 0.5, 0.7 and 0.9MPa at 20°C. The higher firmness advantage declined by 5 day of ripening after treatment, with higher firmness only being retained for fruit from the 0.9MPa at 20°C and the 0.1MPa at 13°C treatments. After 10 day ripening, firmness was similar for all treatments. Lightness (L*) and hue angle were greater for all treatments compared with the 0.1MPa at 20°C treatment. However, only the greater hue angle difference was maintained after 5 day of ripening. After 10 day ripening, no significant differences were found in color attributes. Only 0.1MPa at 13°C retained higher soluble solids, lower titratable acidity and higher TSS:TA ratios after treatment and after 5 day ripening. At 10 day of ripening none of the quality attribute differences noted were retained for any of the treatments. These results show that the only consistent effect of hyperbaric treatment at 0.5, 0.7 and 0.9MPa was to reduce weight loss and enhance firmness retention up to 5 day ripening after treatment.

Evaluation of composition and quality parameters of jelly palm (Butia odorata) fruits from different regions of Southern Brazil

Fruits of Butia odorata from two different regions of Southern Brazil were evaluated in three harvests (2009, 2010 and 2012) in relation to biometric, color and quality parameters, proximate composition and fatty acids profile. The genotypes presented different pulp yields ranging from 40.38% to 73.91% with the highest values observed for genotype SM2. The Hue angle was higher for Santa Rosa in comparison with Santa Maria region and indicated an orange color of fruits. The total solid soluble to total titratable acidity ratio showed values between 4.42 and 14.20 with a high variation in regions, genotypes and harvests studied. The total lipid content reached up to 2.27% within different genotypes and sixteen fatty acids were identified being the palmitic, linoleic and alpha-linolenic acids found in higher amounts. According to results it was possible to discriminated samples from different regions mainly due to different total lipid content, fatty acids profile and color parameters. The genotypes and harvests differed among them, but in the principal component analysis no group formation was observed.

Quantificação da divergência genética entre acessos de goibeira por meio da estratégia Ward-MLM

O presente trabalho teve como objetivo quantificar a divergência genética entre 138 acessos de goiabeira procedentes do banco de germoplasma da Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF), com base em descritores morfológicos, agronômicos e físico-químicos, por meio do procedimento Ward - Modified Location Model (MLM). Para tanto, foram avaliados 13 descritores, sendo cinco qualitativos (coloração da polpa, superfície do fruto, formato do fruto ao final do pedúnculo, largura do pescoço e uniformidade da cor da polpa) e oito quantitativos (massa média do fruto, diâmetro longitudinal do fruto, diâmetro transversal do fruto, rendimento da polpa, teor de sólidos solúveis totais, acidez do fruto, relação teor de sólidos solúveis totais e acidez do fruto e teor de ácido ascórbico). Detectou-se ampla variabilidade genética pelos dados morfológicos, agronômicos e físico-químicos nos 138 acessos de goiaba. Pelo procedimento da função da verossimilhança, determinou-se oito o número ideal de grupos, com um valor de incremento de 67,51. O grupo III foi considerado o mais distante, enquanto os grupos I, II, IV, V e VI, os mais próximos. O procedimento Ward-MLM é uma ferramenta útil para detectar divergência genética e agrupar os acessos utilizando, simultaneamente, variáveis qualitativas e quantitativas.

Induced soil microbial suppression of banana fusarium wilt disease using compost and biofertilizers to improve yield and quality

Banana production has been severely hindered by fusarium wilt disease. The application of organic amendments to soil has been proposed as a strategy for management of the soil borne disease. The one-year effects of different composts and bio-organic fertilizer (BIO) on banana fusarium wilt disease incidence, crop yield, crop quality, and the soil microflora were investigated in field condition. A plate count method, real-time PCR, and PCR-DGGE were used to investigate the soil microflora. The BIO application more effectively controlled fusarium wilt disease. The highest total soluble sugars (TSS) to titratable acidity (TSS/TA) ratios, banana yield, culturable and total soil bacteria populations, and culturable actinobacteria population were observed from the BIO treatment. The ratio of bacteria to fungi (B/F) and actinomycetes to fungi (A/F) values from the plate count method and the B/F value from the real-time PCR analysis were also highest in the soils collected from the BIO application. Based on PCR-DGGE results, the soil bacteria structure was significantly altered in the soils collected from BIO treatment compared to the other treatments. All the results confirmed that application of bio-organic fertilizer could more effectively control fusarium wilt disease in field conditions by improving soil microbial communities.

Optimal Ripeness Stage for Processing ‘Kent’ Mangoes into Fresh-cut Slices

The optimal ripeness stage for processing and marketing fresh-cut mangoes (Mangifera indica ‘Kent’) with best quality and maximum shelf life was determined. The initial ripeness stage selection was based on whole fruit firmness because this quality attribute was more reliable in predicting fresh-cut shelf life than flesh color or soluble solids content (SSC). Overall, the visual quality deteriorated differently and at different rates among ripeness stages. The shelf life, based on subjective visual evaluation, was 10, 7, and 5 days for ripeness stages corresponding to an average flesh firmness of 35, 30, and 25 N, respectively, and was mainly limited by desiccation and development of off-odor for the two firmer ripeness stages or symptoms of edge tissue damage and spoilage for the least firm stage. The slices from fruit with the highest initial firmness remained firmer during storage, had the lowest pH and SSC to titratable acidity (TA) ratio, and had the highest contents of volatile ketones and esters. The softest slices had the highest pH, SSC:TA ratio, and total ascorbic acid (TAA) content, as well as the lowest TA and highest volatile aldehyde and alcohol contents. Intermediate firmness slices had intermediate pH, SSC:TA ratio, color, and TAA content. Also, they had less volatile alcohols and aldehydes than slices from riper fruit but had similar content of esters as slices from the less ripe fruit. Therefore, based on the results from this study, an initial firmness of 30 N is recommended to process mangoes into fresh-cut slices because it assures the best quality and maximum shelf life based on textural, visual, and compositional attributes.

FOLIAR APPLICATION OF BORON INFLUENCES THE LEAF MINERAL STATUS, VEGETATIVE AND REPRODUCTIVE GROWTH, YIELD AND FRUIT QUALITY OF ‘KINNOW’ MANDARIN (CITRUS RETICULATA BLANCO.)

The effects of foliar application of boron (B) in the form of boric acid on vegetative and reproductive growth, yield and fruit quality of ‘Kinnow’ mandarin (Citrus reticulate Blanco.) were investigated. Kinnow mandarin was sprayed with different concentrations of boric acid viz. (0.1%, 0.2%, 0.3% and 0.4%) at fruit set stage. Leaf nitrogen (N), phosphorus (P), potassium (K), B, and zinc (Zn) along with flush length, tree height, tree spread and tree trunk diameter increased, while leaf length and leaf age showed non-significant results after foliar B application. Yield of the ‘Kinnow’ mandarin was significantly affected by foliar application of B and a significant increase in fruit weight at harvest was also observed. Soluble solid concentration (SSC): titratable acidity (TA) ratio, ascorbic acid, total sugars, total phenolic content (TPC) and total antioxidants significantly affected, while pH of juice, SSC, TA, reducing sugars and non-reducing sugars showed non- significant results.

Comparative Evaluation of Plant Growth Regulators for Preventing Premature Fruit Drop and Improving Fruit Quality Parameters in ‘Dusehri’ Mango

Fruit drop is a major problem resulting in low production and reduction in the income of mango growers in tropical and subtropical regions. Growth regulators, naphthalene acetic acid, gibberellic acid, and 2, 4-dichloro phenoxy acetic acid at the rates of (15, 25, and 35 ppm) were sprayed at full bloom stage on a popular mango cultivar ‘Dusehri’ growing in the subtropical region of Faisalabad in Pakistan. All of the treatments significantly influenced the number of fruits retained at pea, marble, and at harvest stages of fruit growth as compared to the control. Among the treatments, gibberellic acid sprayed at 35 ppm proved to be very effective with 31% more fruit retention than the control. In regard to fruit quality, gibberellic acid (35 ppm) and 2, 4-dichloro phenoxy acetic acid (15 ppm) resulted in a significant enhancement of fruit size in terms of fruit weight (140.8 and 130.1 g), which was 17.6 and 8.7% that of the control (119.8 g), respectively. The treatment 2, 4-D (35 ppm) recorded significantly higher TSS (19.5 °Brix) and TSS to titratable acid ratio over the control. Ascorbic acid content was significantly higher with 35 ppm NAA (61.9 mg/100 ml), while total sugars (20.4%) were significantly higher in 2, 4-D (35 ppm) than the control (11.4%). In general, application of growth regulators resulted in improved fruit retention and fruit quality.

ROLE OF BRASSINOSTEROIDS IN MANGO FRUIT RIPENING

ISHS XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Postharvest Technology in the Global Market ROLE OF BRASSINOSTEROIDS IN MANGO FRUIT RIPENING

Application of carnauba-based wax maintains postharvest quality of 'Ortanique' tangor

This study aimed at evaluating compositional changes in the quality of 'Ortanique' tangor after coating with the carnauba-based waxes Aruá Tropical® or Star Light®. The storage conditions studied simulated those of local marketing (22 ± 2 °C, 60 ± 5% RH). Non-destructive analysis, mass loss, peel color, and sensory evaluation, were performed upon coating and every three days up to the fifteenth day of storage. Destructive analysis, peel moisture content, chlorophyll of the peel, pulp color, juice content, soluble solids (SS), titratable acidity (TA), pH, and soluble solids to titratable acidity ratio, were performed upon coating and every four days up to the sixteenth day of storage. The assay was conducted using an entirely randomized design, with three replications (destructive analyses) or ten replications (non-destructive analyses), in a split plot scheme. Wax-coating, especially Aruá Tropical®, maintained fruit freshness by reducing mass loss and peel dehydration and retaining green color. Peel moisture content, chlorophyll content, and juice content had lower rates in the wax coated fruits. Puncture force, soluble solids, titratable acidity, pH, and soluble solids to titratable acidity ratio varied vary little over the course of storage. Sensory evaluation showed that the application of Aruá Tropical keeps 'Ortanique' tangor fresher for 6 days longer for commercialization.

Reflectance Vis/NIR spectroscopy for nondestructive taste characterization of Valencia oranges

The feasibility of reflectance Vis/NIR spectroscopy was investigated for taste characterization of Valencia oranges based on taste attributes including soluble solids content (SSC) and titratable acidity (TA), as well as taste indices including SSC to TA ratio (SSC/TA) and BrimA. The robustness of multivariate analysis in terms of prediction was also assessed. Several combinations of various preprocessing techniques with moving average and Savitzky–Golay smoothing filters, standard normal variate (SNV) and multiplicative scatter correction (MSC) were used before calibration and the models were developed based on both partial least squares (PLS) and principle component regression (PCR) methods. The best models obtained with PLS method had root mean square errors of prediction (RMSEP) of 0.33°Brix, 0.07%, 1.03 and 0.37, and prediction correlation coefficients (rp) of 0.96, 0.86, 0.87 and 0.92 for SSC, TA, SSC/TA, and BrimA, respectively. It was concluded that Vis/NIR spectroscopy combined with chemometrics could be an accurate and fast method for nondestructive prediction of taste attributes and indices of Valencia oranges. Moreover, the application of this technique was suggested for taste characterization, directly based on BrimA which is the best index related to fruit flavor rather than determination of SSC or TA alone.

Assessment of the Validity of Maturity Metrics for Predicting the Volatile Composition of Concord Grape Juice

Total soluble solids (TSS) are typically used as the sole metric for maturity of Concord grapes. However, the reliability of TSS in predicting the aroma composition of finished juice for grapes sourced from multiple sites has not been investigated. This study sought to determine the validity of TSS in predicting the aroma composition of the juice while also investigating other potentially useful indicators, including pH, titratable acidity (TA), and TSS:TA ratio. Grapes were harvested from 9 sites in the Lake Erie Concord Grape Belt and stratified from north to south and east to west. The key aroma compounds methyl anthranilate ("grapey") and trans-2-hexenal ("herbaceous") were quantified along with several other odorants. It was observed that while TSS was a robust predictor of monomeric anthocyanin content across sites, it was a poor predictor of aroma compounds in the finished juice. Conversely, pH, TA, and TSS:TA ratio were all significantly correlated with methyl anthranilate and trans-2-hexenal concentrations (P < 0.05) in samples equal to or exceeding 15 Brix, the industry minimum for grape maturity. These results indicate that parameters related to acidity are better predictors of aroma composition than TSS, which may aid in efforts to minimize herbaceous off-aromas and optimize the aroma composition of the finished juice.