Temperature sums experienced before harvest partially determine the post‐maturation juicing quality of oranges grown in the Murrumbidgee Irrigation Areas (MIA) of New South Wales

Fruit acid levels are important to maturity standards for both fresh fruit and juice acceptability for processing oranges. Citrus fruit maturity standards are based on sweetness (Brix), titratable acidity (% acid) and their ratio. Harvest of Navel oranges for fresh juice can extend for up to 3 months (August–October) and for as long as 7 months (November–June) for Valencia oranges after they first reach acceptable fresh market maturity. Juice processors encourage ‘late hanging’ of fruit on trees to secure a continuous supply of fresh juice. During this time, gradual changes occur in % acid, Brix and juice content. This study tested the hypothesis that a significant proportion of the variation in fruit quality late in the harvest season could be accounted for by environmental conditions during the period that the fruits were left on the trees. Fruit juice quality was assessed in terms of Brix and % acid at the time of harvest for 19 000 fruit deliveries during a 9 year period from 1988 to 1996. The relationship between quality (Brix and acid content) and temperature sums (effective heat units—EHUs) for the period the fruits were held on the trees was tested. A temperature sum (‘day degree’) model for predicting relative changes in acid and Brix content of late‐harvested fruit was developed for both Valencia and Navel oranges. The juice acid relationship with EHUs was stronger than the Brix relationship with EHUs. In addition, the seasonal ‘behaviour’ of % acid was more consistent than that of Brix in both Valencia and Navel oranges. A linear reduction in % acid with increasing EHUs was evident in both varieties. Estimates of fruit quality (Brix/acid ratio) at harvest time should be made using the equations describing changes in % acid with EHUs and the relationship between Brix and % acid to determine Brix. These equations have potential use in predicting the internal quality of citrus fruit during extended harvest periods. EHU‐based fruit quality estimates could determine harvest schedules that enable growers to achieve the optimum factory price for their fruit whilst maximising returns to processors through more efficient product utilisation. © 2000 Society of Chemical Industry     

Relationship of acid phosphatase activity and Brix/acid ratio in cherries

This research was undertaken to determine the relationship of acid phosphatase and Brix/acid ratio in cherries. High-acid cultivars of cherries (Karneol, Northstar, Kroeker, Danube, Montmorency, Oblinska, and Topas) exhibited low Brix/acid ratios while low-acid cultivars of cherries (Balatron, Sweetheart, Hedelfingen, and Hudson) had high Brix/acid ratios. The values of correlation coefficient (r²) for acid phosphatase and Brix/acid ratio in different cultivars grown in 2003 and 2004 were 0.88 and 0.84, respectively. An inverse relationship appeared to exist between the acid phosphatase activity and the acidity in cherries, and the r² values for 2003 and 2004 crops were 0.97 and 0.81, respectively. The plot of acid phosphatase vs. Brix in cherries showed a positive slope, and the r² values for 2003 and 2004 crops were 0.89 and 0.88, respectively. The results of this study indicate that acid phosphatase could serve as a marker for breeding new fruit cultivars with a desirable Brix/acid ratio.     

Epidemiology of bovine colostrum production in New York Holstein herds: Prepartum nutrition and metabolic indicators

Colostrum yield and quality are influenced by prepartum nutrition and the metabolic status of the cow; however, data considering these associations on multiple dairy farms are limited. Our objective was to identify cow-level prepartum metabolic indicators, as well as farm-level nutritional strategies associated with colostrum yield and the indicator of colostrum quality, Brix %. A convenience sample of 19 New York Holstein dairies (median: 1,325 cows; range: 620 to 4,600 cows) were enrolled in this observational study. Records for individual colostrum yield and Brix % were collected by farm personnel between October 2019 and February 2021. Farms were visited 4 times, approximately 3 mo apart, to obtain feed samples of the prepartum diets, collect blood samples from 24 pre- and postpartum cows, respectively, and determine prepartum body condition score. Feed samples were submitted for analysis of chemical composition, and particle size was determined on-farm using a particle separator. Prepartum serum samples (n = 762) were analyzed for glucose and nonesterified fatty acid concentrations. Whole blood from postpartum cows was analyzed for herd prevalence of hyperketonemia (proportion of samples with β-hydroxybutyrate ≥1.2 mmol/L). A cohort of primiparous (PP; n = 1,337) and multiparous (MPS; n = 3,059) cows calving ± 14 d of each farm visit were included in the statistical analysis. Animals calving in this period were assigned results for the close-up diet composition and herd prevalence of hyperketonemia collected from the respective farm visit. Greatest colostrum yield from PP and MPS cows was associated with moderate starch [18.6–22.5% of dry matter (DM)] and a moderate herd prevalence of hyperketonemia (10.1–15.0%). Greatest colostrum yield from MPS cows was associated with moderate crude protein (13.6–15.5% of DM) and a less severe negative dietary cation-anion difference (DCAD; >−8 mEq/100 g), whereas greatest colostrum yield from PP cows was associated with low crude protein (≤13.5% of DM). In addition, a moderate proportion of the diet with particle length ≥19 mm (15.3–19.1%) was associated with lowest colostrum yield from PP and MPS cows. Highest colostrum Brix % was associated with prepartum dietary factors of low neutral detergent fiber (≤39.0% of DM) and high proportion of the diet with particle length ≥19 mm (>19.1%). In addition, low starch (≤18.5% of DM) and low and moderate DCAD level (≥−15.9 mEq/100 g) were associated with greatest Brix % from PP cows, whereas moderate DCAD (−15.9 to −8.0 mEq/100 g) was associated with greatest Brix % from MPS cows. Prepartum serum nonesterified fatty acid concentration ≥290 µEq/L was associated with increased colostrum yield, but prepartum serum glucose concentration and body condition score were not associated with colostrum yield or Brix %. These data provide nutritional and metabolic variables to consider when troubleshooting colostrum production on farms.     

Sugars,acids, ethyl β-d-glucopyranose and a methyl inositol in sea buckthorn (Hippophaë rhamnoides) berries

Sea buckthorn berry is a rich source of nutrients and bioactive components beneficial for human health. Sugars and acids play an important role in determining the sensory properties of the berry. Sugars, acids, ethyl β-d-glucopyranose and a methyl inositol were analysed in berries of three subspecies (Hippophaë rhamnoides ssp. sinensis, rhamnoides and mongolica) collected from China, Finland and Russia over four consecutive years. Fructose and glucose were the major sugars, and the dominating acids were malic and quinic acids. Origin and harvesting date have significant impacts on sugars, acids and sugar/acid ratio in the berry. During the harvesting period, the sugar content followed different changing patterns in berries of different subspecies. Ethyl glucose dominated in the sugar fraction of ssp. rhamnoides but existed only in trace amounts in the other two subspecies. In ssp. rhamnoides, the level of ethyl glucose increased during the harvesting period; the increase was accompanied by a decrease in glucose content, indicating the presence of a biochemical pathway converting glucose into its derivatives. A methyl inositol was identified for the first time in sea buckthorn with higher levels found in ssp. sinensis than in the other two subspecies. The levels of ethyl glucose and methyl inositol may be important sensory and nutritional quality factors of sea buckthorn berry. The data presented by this study provide important chemotaxonomic information characterising different subspecies of sea buckthorn and useful guidance for breeding, harvesting, and industrial utilisation of sea buckthorn.     

Maturity criteria for litchis (lychees)

Five varieties of litchi (lychee) were harvested from five different locations over a period of two years. The fruit varied from immature to almost fully mature. It was subjected to taste testing and analysed for total soluble solids (TSS) and titratable acidity (A). TSS (°Brix) was not suitable as a maturity indicator whereas titratable acidity and the TSS/A ratio were both good predictors of taste. A titratable acidity of 4.4 cmol H⁺ kg⁻¹ juice or a TSS/A ratio of 4.3 Brix.kg juice cmol⁻¹ H⁺ would be suitable maturity indexes.     

Accuracy of direct and indirect methods for assessing bovine colostrum quality using a latent class model fit within a Bayesian framework

Feeding high-quality colostrum is essential for calf health and future productivity. Therefore, accurate assessment of colostrum quality is a key component of dairy farm management plans. Direct and indirect methods are available for assessment of colostrum quality; however, the indirect methods are rapid, inexpensive, and can be performed under field settings. A hierarchical latent class model fit within a Bayesian framework was used to estimate the sensitivity (Se) and specificity (Sp) of the radial immunodiffusion (RID) assay, transmission infrared (TIR) spectroscopy, and digital Brix refractometer for the assessment of low-quality bovine colostrum in Atlantic Canada dairy herds. The secondary objective of the study was to describe the distribution of herd prevalence of low-quality colostrum. Colostrum quality of 591 samples from 42 commercial Holstein dairy herds in 4 Atlantic Canada provinces was assessed using RID, TIR spectroscopy, and digital Brix refractometer. The accuracy of all tests at different Brix value thresholds was estimated using Bayesian latent class models to obtain posterior estimates [medians and 95% Bayesian credibility intervals (95% BCI)] for each parameter. Using a threshold of <23% for digital Brix refractometer and <50 g/L for RID and TIR spectroscopy, median (95% BCI) Se estimates were 73.2 (68.4–77.7), 86.2 (80.6–91.0), and 91.9% (89.0–94.2), respectively. Median (95% BCI) Sp estimates were 85.2% (81.0–88.9) for digital Brix refractometer, 99.4% (97.0–100) for RID, and 90.7% (87.8–93.2) for TIR spectroscopy. Median (95% BCI) within-herd low-quality colostrum prevalence was estimated at 32.5% (27.9–37.4). In conclusion, using digital Brix refractometer at a Brix threshold of <23% could reduce feeding of low-quality colostrum to calves and improve colostrum and calf management practices in Atlantic Canada dairy herds. The TIR spectroscopy showed high Se in detection of low-quality colostrum. However, the RID assay, which is used as the reference test in several studies, showed limited Se for detection of low-quality colostrum.